GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION
166
B.A.R.C.-716 IV. U m GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION ANALYTICAL CHEMISTRY DIVISION ANNUAL PROGRESS REPORT FOR 1972 Compiled by M. Sankar Das and R. M. Sathe Analytical Chemistry Division BHABHA ATOMIC RESEARCH CENTRE BOMBAY. INDIA 1973
Transcript of GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION
B.A.R.C.-716
IV.
U
m
GOVERNMENT OF INDIAATOMIC ENERGY COMMISSION
ANALYTICAL CHEMISTRY DIVISIONANNUAL PROGRESS REPORT FOR 1972
Compiled by
M. Sankar Das and R. M. SatheAnalytical Chemistry Division
BHABHA ATOMIC RESEARCH CENTRE
BOMBAY. INDIA
1973
B./ .H.C.-716
GOTERNHSET OP INDIAATOMIC ENERGY COMMISSION
oen
«•<
m
ANALYTICAL CHEMISTRY "DIVISIONAMHUAL PROGRESS 11EPOET PCS 1972
Compiled by
M. Sankar Das and R.M. SatheAna ly t i ca l Chemistry Divis ion
BfUHIA ATOMIC RESEARCH CENTREj INDIA
1973
INTRODUCTION
This is the second time that we are bringing out
the Annual Keport on the activities of the Analytical Chemistry
Division in the new format. The rationale behind this new
mode of presentation has been explained earlier.
Problems that we face in the Analytical Chemistry
Division have often a specific and limited objective i.e., the
determination of the desired element at a certain concentra-
tion level in a given matrix. We will cconsider the purpose
of this report amply served if somebody, somewhere, is spared
of a duplication of effort in the solution of a similar
problem.
In general, analytical assistance in the execution
of various projects and help in the pursuit of the developmental
work by different units of BARC and DAE, continued to be the
prime coefficient of our effort during the current year.
Special chemical analysis undertaken for outside institutions
yielded a revenue of Rs.13,000/-, a remarkable increase over
the sum of Rs.4,000/- realised last year. In all,about 2000
samples were analysed involving 6000 determinations (App. I).
Pieces of work that merit special mention are;
i) Development of methods for (s.) the analysis of
impurities in liquid sodium to be used for the fast reactor
programme at Kalpakkam (b) rapid analysis (3 min/sample) of
n a wide variety of materials by counting the delayeduranium in
-ii-
fiaaion neutrons emitted on neutron activation, (c) investi-
gation oi" surface and depth distribution of fluorine in
zircaloy by proton activation.
i i ) Commissioning of (a) the solid source mass
spectrometer GRAAF-3 after overcoming a lot of vacuum problems
and (b) a Leco WR-12 carbon analyser.
i i i ) Fabrication of (a) a power supply for hollow
cathod lamps used in the atomic absorption and fluorescence
work and (b) a voltage scanning device for stripping analysis.
The supporting research work, as before, centred
round the study of coordination compounds. The conventional
techniques of investigation have now been supplemented by those
of nuclear magnexic resonance, infra-red spectrophotometry,
bomb and solution calorimetry etc. Other areas covered
include electrode kinetics, gas chromatography, ion exchange,
therrcogravimetry and forensic activation analysis.
Information about some useful pieces of equipment
fabricated by the Electronics maintenance unit ha-re also been
included.
A break up of samples analysed, l ists of scientific
publications together with details of other peripheral activi-
ties are given in the respective appendices.
C O N T E N T S
INTRODUCTION i
1 DEVELOPMENT WORK
1.1 Nuclear methods 1
1.2 Spectrophotometry 15
1.3 Atomic absorption and atomic fluorescence 26
1.4 Electroanalytical and other methods 31
2 RESEARCH WORK
2.1 Physicochemical investigations ofcoordination compounds 37
2.2 Electrode kinetics and electrochemical
studies 83
2.3 Forensic Science 116
2.4 Ion exchange s tudies 118
2.5 Gas chromatography 121
3 FABRICATION AND SETTING TIP OF EQUIPMENTS
3.1 Solid Source Mass Spectrometer 123
3.2 Carbon analys is by LeOo WR-12 analyser 125
3.3 Pyroaydrolytic determination of fluoride 1263.4 Continuous flow apparatus for surface area
measurement 127
3.5 Electrodeless discharge tubes for atomicabsorption and fluorescence 128
-iii-
-iv-
3.6 A power supply for hollow cathode lamps 129
3.7 Beckmann DU power supply 130
3.8 Sweep supply unit for anodic strippingvoltammetry 131
3.9 Conductivity bridge 132
3.10 Manual polarograph 133
3.11 Chart area integrator 134
4 APPENDICES
1 . DEVELOPMENT WORK
K 1 NUCLEAR METHOD3
1,1 (1) l e o t o p l o a n a l y s i s of uranium by alpha speotrometryi
(B.L.Sao , P.P.Parekh, CLK.Reddy and M.Bankar Das)
A method for the determination of the amount of
uranlum-235 In enriched uranium samplea hae been deve-
l o p e d ' 1 ' . I t i s based on the f a c t that the < < - a c t i v i t y of
uranium-234 i s d i r e o t l y r e l a t e d t o the oonoentration of
uranlum-235» expressed in atom per oent upto a t l e a s t about
enrichment.
The sources were prepared by e l e c t r o - d e p o s i t i n g(2)on to a copper disc from an oxalate mediunr . In
order to maintain the oonstancy of absorption and scattering
effects influencing the alpha-activity measurements, the
amounts of uranium were controlled to + 50 )2g at 200 jig.
The alpha spectra were taken using a gold coated surface
barrier silicon detector, coupled to a 400 channel analyser,
through a pr«-amplifier and a low noise amplifier. The area
under the 4*71 + 4»77 MeV peak of uranium-234 was measured
and plotted against uraniua-235 concentration. Uranium
oxides of known isotopio composition, obtained froa the
Rational Bureau of Standards, U8A9 were used for oalibra*-
tion (Flg«I). The measured alpha activities of two unknown
enrichments Bj and K^ have also been included. Comparison of
results for these earnpies (Table 1) indicates satisfactory
ftoouraey for the present methods
-2-
TABLE 1
Analysis of uraiiium-235 by alphaepeotrometry and other methods
Uranium-255 concentrationSample 7
p Kaes Belayedapeotrometi^r apeotrometry neutron
oounting
S-1
E-2
1
2
.31
.28
•
±0.02
0.08
1
2
.37
.16
±±
0
0
.01
.01
1.37
2.02
1, B.L.Rao, P.P.Parekh, G.R.Reddy and tt.Sankar Daa,
Anal.Ohim.Aota (In preae)
2. S.Cohen and 2).E.Hull, Manhattan Project Report
No. A-1235 (1944)
1«1 (2) Estimation of uranium by delayed neutron oountingt
(G.R.Reddy, D.R.Pant and M.Sankar Dae)
Analysis of uranium by ooumting the delayed
neutrons emitted by some of the fission produots has been
»hoim'1>8»3* to be a simple, preoise and rapid method.
A neutron oounting system was, therefore, fabricated for
the purpose. I t consists of a 4-n neutron detector and
assooiated eleotronloa as ?hovm in fig ,11. The neutron
detector Is a ring of eight B10Fj oounters (dia. 2.5",
length 12") embedded in a block of paraffin wax. These
are operated In parallel from a common supply of'high
- 3 -
voltaga. The detector i e shielded from external neutrons
by 6" borated paraffin blocks. The system has ah overall
detection efficiency of 8-100 for neutrons from an Am2*1-Be
neutron souroe.
The system, in oonjunotion with a thermal flux13 —2 —1
of 6 x 10 n.om .sec . available in the OIRUS pneumatic
irradiation fao i l i ty , can conveniently detect 0.1 jug amount
of uranium. The procedure consists of sealing the sample
(100-200 mg) in a small, olean polythene bag, Inserting I t
into an irradiation container made of polypropylene (rabbit)
and irradiating for a predetermined time. A definite delay
period (usually 30 sec.) was allowed, Bo that 4.2 sec. N17,
a delayed neutron emitter, decayed to negligible level
before the sample was actually counted. Counting timea were
generally 60 sec , , but irradiation and delay times were
varied according to the uranium content of the samples. Thus,
/or reck samples, they were kept at 60 sec. and 30 s e c res-
pectively, but when uranium was present in significant quan-
t i t i e s , these were so chosen as to minimise the ooincidenoe
losses , du* to high neutron oount rates .
Table 2 presents comparative data for the analy-
s i s of some typioal samples analysed by different methods*
1. S.Amiel, IA-621, 1961.
2. F.F.Dyer, J.P.Bmery and G.W.Leddieote, GRNL-3342, 1962,
3. N.H.Oale, Radioactive dating and methods of low level
counting, IAEA Symposium, Vienna, 1967, pp.431*
TABLE 2
A comparison of data for uranium analysis bydelayed neutron and other methods
Sample
I . .ORESa) BBL carnotiteb) BBL phosphate rockI I . ttTHEBALSa) Zircon (HK)b) GalenaI I I . ROCKSa) Granite G-2b) Tonalite T->1IT. SOILSa) Sample 1949b) Sample 1945T. BIOLOGICAL SAMPLESa) Halr-1b) Hair-2
Measurement*time (sec.)
*i *d Tc
30 30 60n it n
60 30 60• n *
w n it« it it
H H ItII ft B
H U Ht> ft m
Result
0.1780.0295
3401.75
1.950.74
2.5426.8
47.985.5
Other methods
Method
ChemicalChemical
Bad.chem.HAA• .
VariousDHM
. . .
V-ray speo.Y-ray spec.
Result5ttJ568
0.180.029
• •
•»> .
• .* a
ppnTJ
289• •
2.050.79
42.787.5
1
Irradiation time; delay time; oountlng
1.1 (3) Heutron activation analysis of lanthanum, scandium
and oobalt in deep aea sediments and manganese nodulest
(B.L.Rao, P.B.Pawaskar, G.R.Beddy and H.Sankar Das)
The following procedure was developed for this
partioular analysis. About 100 mg of the irradiated sample
in the praBenoe of the respeotive oarriers was treated with
hydrofluoric acid and nitrio acid, to expel., ailioa and fumed
with a few drops of sulphuric acid* The residues were taken
up in dilute hydroohlorio acid, and hydroxides were precipi-
tated using excess ammonia. After about 4 hours, the hydroxi-
des were filtered, dissolved in dil. HC1 and repreoipitated
so that all scandium and lanthanum remained in the precipi-
tate while cobalt passed into the filtrate as its ammonia
complex. The precipitate was dissolved in dilute hydroohlorio
acid and made upto 25 ml for activity measurements.
Prom the combined filtrate, ammonium salts were
removed by repeated treatment with nitric acid. The residue
was taken up in 8 N hydrochloric acid and diluted to 25 ml
with the same acid for activity measurement.
Measurements were made initially under 1.59 MeV
photopeak for lanthanum which was then allowed to deoay
completely before scandium measurements were takon under
0.889 MeV photopeak. ,
Oobalt waa assayed by measuring under 1.33 MeV
photopaak ©f Co60. Th? Intensity of th« ohloro eemplwc of
-6-
eofcalt as measured at 625 nm using a Beckman W opeotrophoto-
meter was. used for determining the chemical yield. Chemical
yields of 80-90* were usually obtained. Results of auch
analyses on1 certain standard rook samples, presented in
Table 3 indicate the acouraoy of the method.
TABLE 3
Comparison of the results for lanthanum, scandiumand cobalt in some standard rock samples
Sample
BCR-1
W-1
0-2
Lanthanumppm
22.6(22-23.7)
11.0(12)
89.6(81-84)
Scandiumppm
31.1(31-33.2)
34.9(34)
3.9(3.0-4.5)
Cobaltppm
33.1(36.0)
49.5(50.0)
• •
Value8 in parenthesis are the literaturevalue8 by neutron activation analysis.
1.1 (4) Analytical application of oharged particle
induced nuolear reactions*!
(S.Gangadharan and S.Y.Subramanian)
In continuation of our previous work'1', the
proton beam from the 5.5 MeV Tan de Graaff accelerator
has been used to investigate the surface and depth
* the o©operation of fir H.A.Saswaran and his group atTan de Graaff i s acknowledged.
-7-
distribution of fluorine in Bircaloy. The problem was
referred to us by the Atomic Fuels Division in which it was
required to examine the surfaces of autoelaved Bircaloy
oladded assemblies and correlate the fluorine content with
some abnormalities in the form of grayish-white patohes.
8everal eircaloy coupons, subjected to varying pickling
times followed by washing and autoolaving as per the pro-
cedure followed for the fuel element assemblies*, were
examined for their fluorine contents to establish the range
of concentrations encountered. The estimation was through
the F(p, < ) 0 reaotion at the 1375 KeV resonance and
the gamma-rays were detected by a 7.6 cm x 7.6 cm Nal(Tl)
crystal and by a ^ 30 o.e. Ge(Ll) detector, the latter
being used for diagnostic purposes. The depth distribution
was obtained by adjusting the bombarding energy such that
the proved tile energy will be in resonanoe at the required
depth after traversal and energy loss in that layer of the
sample. A ixomogram has been constructed to caloulate the
initial energy for any given depth for the major resonance
in the excitation funotion for this reaction. Computation
of the depth distribution of the impurity was done by
taking into account the excitation function. Fig.Ill show*
the results for a particular position In a sample. Fuel
• The cooperation of Shri K.Balaramamoorthy of the AtomioFuels Division is acknowledged.
- 8 -
elements showing abnormal surfaoe characteristics have been
scanned along the length for the surfaoe fluorine content
and the depth distributions have been determined for a few
plaoee. There does appear to be some positive correlation
between the grayish-white patches and the surfaoe fluorine.
The depth resolution attainable i s < 0.2 u and the sensi-
tivity i s estimated as ^ 0.05
1. Annual Report, Analytioal Chemistry Division, 1971*
2. S.Gangadhar&n and 8.Y.8ubramanian, "Surface analysis
and depth distribution of impurities using charged
particles; Fluorine in Blrcaloy", BARC-654, 1972*
1.1 (5) 14 MeY nautron activation
(S.Gangadharan and ScY.Subramanian)
In continuation of the work reported last year,
the 14 MeV neutron generator at Electronioa Division, has
been used to determine several elements like fluorine, s i l i -
con, aluminium, phosphorus, potassium, molybdenum and tung-
sten in various synthetic samples and also in matrices such
as steels and minerals. Measurements have been carried out
with Nal(Tl) deteotor ooupled to a 400-ohannel pulse height
analyser. Table 4 gives some of the results and the praoti-
oal sensitivities estimated with the available neutron output
and the "background" in the energy region of interest. Tht
interferences have been evaluated by irradiating synthetic
- 9 -
f
3u o
I!o e
SI*
1
sP4
ASM a
CM CM
o inin CM
• •o o
cr>in o CM
\© r-• •
CM CM 00
in in cwt~ m CM *- vo in
m coCM CM
© o © vo cf> n ^ITS CM
CM CM
*
«> tn
03 S n ^ *
* s "it IrCM CM H • i
SOinSM CM CM
en CMCM m
o
vooo
m
H«
VO
a
CM
t
o
to«i
0in
•
•
•O
*l
aO
•
CTin
•CM
7
in•
in
•
r-CM
•
1
a
•
oin
aw fl w -Ef
H
-10-
aixtures. The effect of sample geometry baa been taken
Into aooount through an investigation of the axial varla-
tlon In the neutron flux by irradiating metal fo i l s at
different dietanoee from the eouroe and also by irradia-
ting aamplea of different thicknesses whloh "oorreot "
for scattering/attenuation aa well*
1 • 1 (6) Eatimation of parta per bi l l ion 1 eve la of copper
in double diatllled waten
(H.B.Desai and R.K.Iyer)
The concentration of copper In the diatllled
water used for the preparation of labelled oo£s by
the Isotope Division, BARG, waa not to exceed parts per
bil l ion levels. The analysis at this level by neutron
activation necessitated the irradiation of 50 ml of the
water sample. The reaotion used i s 0u(n,v)6*Cu. A
method waa developed to normalise the neutron flux in the
case of Buch large samples so that the activity ratio of
sample to standard can be related to the amount of copper
present. Thia was accomplished by the use of a sample-
standard configuration during irradiation which would com-
pensate for the flux va*Utloii» i i ,«as shown by activity
measurements,using two standards and two samples of 50 ml
each, that flux normalisation could be achieved within
-11-
5-1 Ojt, though the flux varies between two adjacent positions
by a faotor of 2.4' » She method proved satisfactory for
estimation of oopper at 2-3 ppb level.
1. H.B.Deeai and E.K.Iyer, Itadloohem.Hadloanal.Letters,13.(2). 75, (1973)
1.1 (7) Estimation of merourvx
(H.B.Deaai, B.K.Iyer and S.R.Kayasth)
(a) in lead and Bine-concentrates* Samples of lead and
sine concentrates were received from Indian Bureau of Mines f
Sagpur, for the analysis of their meroury oontenta* The pre-
Benoe of appreciable amount of antimony and leeeer amounts
of silver interfered with tho measurement of mercury aotlvity
produced and this necessitated a suitable radioohemioal sepa-
ration procedure.
The procedure developed consisted of sodium
peroxide fusion of the sample in the presence of carriers
for silver and meroury, followed by the removal of antimony
as soluble antimonate. The residue was dissolved in nitric
aold and silver aotivlty was removed as silver ohlorlde.
Toe meroury fraction was further purified by precipitation
as mercurous ohlorlde and counted.
anthraquinone, an Intermediate produced by M/e Indian Dye-*
stuff Industries, Salyan, were to be analysed for mercury
-12-
which la used as a catalyst in the preparation of thi6
compound. The analysis itself could be completed by a direct
meaourement of the activity of 97Bg + Hg, but some of
the samples showed inhomogeneoue distribution of mercury, ^ e
concentration varyin*. by. as muoh as a factor of 10.
1,1 (8) Estimation of platinum in lead buttons by activation
analysis i
(R.K.Iyer and R.Parthasarathy)
A few samples of laad buttons derived froa
eilioate samples were analysed for their platinum content to
evaluate the reoovery of platinum by oupellation. The nuo-
lear reaction used was 198PHn»^)li9Pt - —* 199Au. After
irradiation, the samples were brought into solution and the199
Au activity was extracted,in the presence of 50 p% of
gold carrier, into ethyl acetate from 2 M hydrochloric aoid.
The activity was brought into aqueous phase after evaporation
of ethyl acetate and analysis completed by the measurementI C Q •• 1QS
of the activity of "Au. The ^Au formed by the reaction9'Au(nvV) Au on the gold present in the sample, limited
the sensitivity of measurement to ^ 5 ppm of platinum.
1*1» (9) Estimation of phost>horuo»
(») in trlphenyl chloromethane by neutron, aotlvationt
(H.B.Desai and B.K.Iyer) . .
Triphenyl ohloromethane i s a oompound used
In the purlfloation of silioon for semioonduotor applica-
tions. The phoBphorua content of this material was to be
estimated in samples supplied by the Chemical Bngineering
Division, BARO.
The values determined 'ay neutron aotivation,
followed by the separation of T* activity aa amaonium molyh*
ddphosphate, varied as much as by a factor of 300 between
Irradiations carried out in Apsara and OIRUS reactors, the
value obtained in Apaara being higher.
So ascertain whether this waa as a result of35 32the Cl(n,*) P reaotioA on ttse chlorine present in the
compound, potassium chloride was irradiated along with the
compound, with and without cadmium wrapping* These irradia-
tions indloated that the induced activity could be accounted
for by this reaetienj hence it was not feasible to analyse
parts per million levels of phosphorus in this compound by
neutron irradiation in either reaotor*
(b) in triabloroeilanet
{O.O.Mas and P.Murugaiyan)
In view of the above, two alternative approa-
ches based on the work of Lancaster and BveringhanriAd West
st al' ' are being pursued*
The former involves the extraction of phos-
phorus with con* sulphuric acid* oxidation to the pentavelen*
state by ptrohlorio field followed by speotrophotometrie deter*
as vanadopfe6spnoffiblybdat«4
In the latter case, phosplMwes Is extracted
a» H3POi(Ko04)12 i n * ° color of tHM£>J&tttanol nixture and deter-
mined indirectly through baok extraction and tfpeotrophoto-
metrio determination of molybdenum In the extraoted species.
1. f.A.Lanoaster and H.R.Bverlngan, Anal.0hem.t J&. 24* CV964).
2. T.iDjurkin, O.P.Klrkbrlght and T.S.West, Analyst, 21, 69,
1966.
1.1 (10) Determination of Individual rare earthsi
(H.B.Deaal, g^Oangadharan and M.8ankar Das)
In continuation of the work reported ear l i er* '
saveral determinationB have been carried out to eetimate Indi-
vidual rare eartha in monaeite and thorium and uranium com-
pounds using high resolution gamma-ray speotrometry. Irradia-
tion* have aleo been oarried out on minerals, diluted with
quartz to minimise self-absorption, to investigate discrepan-
cies in the sample preparation. The contribution of neutron
spectrum has been Investigated through irradiations in ano-
ther reactor and in the thermal column. The interferences
from the fission products arising from the uranium oontent
are being determined experimentally for the irradiation
position»
Borne thorium samples from Indian Rare Earths
and Ohemloni Engineering Division, BAHO and a few ammcniun
fiiuranate aamples have been analysed tw lanthanum„ eerlua,
praseodymium; neoflyral«s, sanariua, europium and dysprosium.
-15-
1.2 8J1O5BOSS0IO1IETBT
1.2 (1)
metal :
(H.P.Bhat, 8.B«hasranaman and M.Sundareean)
The presence of ohlorlde in quantities higher
than 20-30 parta par million In a odium mttal used as a
ooolant in fast reactors, aooeleratea corrosion In atalnleaa
steel pipes, further, tor smooth filtration of eodium metal
through, atalnlaaa steel gauge, there la a restriction on
the total impurities,,
The usual method of tltration of ohloride
with silver nitrate auffera from masking of the end point
due to the high ionlo strength of the sample solutions, The
present method is free from this diffioulty and is based on.
the faot that ohloride ions when added to a solution of
merourlo thiooyanate and ferric iron produoe red ferrio
thiooyanate whloh oan be measured speotrophotometrioally* K
About 1 g sodium netal was dissolved in water
under inert atmosphere and the sodium hydroxide formed was
neutralised with perohlcrlo told. One ml of a saturated
solution of merourio thiooyanate and 2.5 ml of ferrio per»
ohlozete (6£ in 1i3 perchloric aold) were added to the
uample aolution eontainud In a 25 ml standard fUsk and
Btade up to the mark, The optical density of the solution
was mnaaured with a Beekman EU •peotrophotometer at 460 am
- 1 6 -
in a 50 mm cuvette, using the reagetil blank as the r
solution. A calibration curve was obtained in a similar
manner using known amounts of chbride in the presence of
equivalent amount of sodium perohlorate in the sample.
The chloride content in sodium metal was further checked by
standard additions of chloride to varying amounts of aodium
samples and determining the final recovery of chloride. A
naw calibration curve was plotted each time, sines the rea-
gents were prepared fresh for eaoh set of experiments. This
method has been applied successfully at a concentration
level of 5-30 parts per million of chloride with an accuracy
of + 10*.
1. Louis Silverman, "The determination of impurities in
nuclear grade sodium metal"» Pergamon Press, New York,
(1971).
1.2 (2) Determination of traces of fluoride in uranium
and oaridet
(S.Ganapathy Iyer, H.Parasurama Iyer and Oh.Venkateswarlu)
Normally fluoride i s estimated by i t s bleach-
ing effeot on aluminium-Chrome aaurol 6 complex at pB
4.25* . Since the method is time consuming, the one emp-
loying the formation of a blue mixed complex of fluoride
t»ith Alizarin fluorine blue and lanthanum has been deve-(2)
.*.©pedv . fluoride i s separated from uranium metal or
-17-
ite oxide by dietillatlon. It Is oomplaxed with l&nthanum
Allsarin oomplexan and extracted into bensyl alcohol and
determined aptiotrophotoaetrioally. The results cm some
oaoplea by both the method a are oompaxed in Table 5. The
present method ia more sensitive, and as low aa 2 ug oan
be determined.
Procedures About 2.0 g uranium aetal or
oxide \rae treneferrad to ft fluorine diatillation fl«ak.
?or the oxid« aanpleae perohlorlo aoid 70# (70 al), hydro*
gen peroxide 30^ (10 ml) and 81D2 (30 ag) were tdded. In
the oaae of uranium natal, 50 ml of water, 20 al of per-
ohlorlo aoid, 10 ml of U2°2 ^^ *nd ^° *& of •*-H°* ^ ^
added in the order given. The temperature wae a lowly
raised to 110*0. After complete disaolution of the sample,
the temperature was raised to 140 + 5*0. 150 ml of the
distillate was collected in dilute sodium hydroxide (5 ml
of 2 H ) . The distillate was made upto 200 ml,
A suitable aliquot was taken in a separating
funnel and neutralised with dll. perohlorio aoid. Buooi-
nate buffer (5 ml) to give a pi 4.61 1i1 mixture of lan-
thanum-Allftarln complexan reagent (2 ml) and aethanol
(10 ml) were added and mixed well. 13ie solution was dilu-
ted to 50 ml.
«r*er 10 roiniD., 2 g of sodium ohlorlde wae
added and i he coloured complex was extracted into
10 ml bensyl alcohol. The organic layer was filtered
through a filter paper and its abaorbanoe measured at
615 nm.
UABLE 5
Comparative results of the two methods
Sample
S 1325
S 1526
B 1527
E 1528
Fluorine ocntent in ppm
Bleaching reao-tlons
210
55
55
HO
Mixed oomplffxextraction
207
57
55
120
1. Y.J.MaoMutty and L.#*Wooland, Anal.Ohim.Aota, J.4.,
•52 (1956)
2. Report, Tluorine 8ub-oommittee» Analyst, 3£, 584 (1971).
1.2 (3) Determination of traces of sine in cadmium -
tin alloya
(a.Oaaapatliy Iyer and H.Parasurama Iyer)
A epeotrftphotometrio method for the deter-
mination of traces of zinc in oadmium-tin al loy has been
standardisedt
-19-
Prooedures 0.5 gm sample waa repeatedly
treated with 4 ml of hydrobrwnio acid and 2 ml of bromine
to dieeolve the sample and expel tin completely. Excess
of bromine was then removed by evaporation with oonc. HOI.
finally two to three drops of dil. HOI were added, the
contents warmed on ft water bath and made up to a known
volume. A imitable aliquot of the solution, adjusted to
pE 4-5 and containing 1-3 ug of aino, was taken in a 100
ml separating funnel. 1 ml of aoetate buffer (4.6 pH),
1 ml saturated thlourea (to mask heavy me tale like Ag,
Bi, Tl eta.), 1 ml of ascorbic aoid (to reduoe Ve**) and
4 gms of potassium iodide (to coaplex oadmiumjh were added
and the aqueous phase equilibrated thrice with 20 ml por-
tions of O.O1£ dithieone in carbon tetraohlorlde by shak-
ing for 2 minutes^ The combined extracts were washed
with a solution containing 200 72 at pH 4*6. The eino
in the organic layer was stripped with two 10 ml portions
of 5jt All* HNO,. The aqueous phase was separated and
evaporated to dryness* A drop of HOI, 10 ml of water and
1 ml of thiourea solution were added to the residue and
the pH of the solution was adjusted to 4.5* 1 ml aoetate
buffer was added and ilno was then extracted with 10 ml
of 0.001)1 dithleone In oarbon tetraohloride by shaking for
2 minutes. The absoclrance was weaeured Immediately at
535 nm, and the Bine content determined from the calibra-
tion ourvt.
-20-
1.2 (4) Determination of boron In copper alloyat
(V.H.Joshi and 0.S.P.Iyer)
Boron ia added to copper alloys to act as a
grain refiner. A method baaed on the work of Fakalns^ *
has been standardised for the estimation of boron in suofc
alloys.
The Bampie was dissolved gently in sulphu-
ric aoid, the dissolution was aided by a few drops of nitrio
aoid. The interference of nitrate in the subsequent deter-
mination was removed by its reduotion to nitrous oxide by
f comic acid. The final colour development with ouroumin
was carried out in an acetic acid - acetic anhydride -
sulphuric acid medium.
1. Pakalns, Analyst, $±t 1130 (1964).
1.2 (5) Determination of germanium in glrconimn alloysi
(V.A.Kamath and C.S.P.Iyer)
Germanium is added to eiroonium, a common
cladding material to prevent hydride formation.
For its determination, a sample of siroonlum-
germanium alloy was brought in solution by fuming with
HgSO^-KHSO^. After maintaining an aoidity of 8 M with rea-
pect to HOI, germanium was extracted into carbon tetra-
ohloride^1'. Itwae then back extracted into water and
estimated using phenyl fluorone.
The possible loss of germanium in each of the
steps involved was evaluated and found to be negligible.
1. E.B. Sand e l l , "Colorlmetric determination of traces of
metals", 1959.
1*2 (6) Determination of sulphate in sireoniurn oxidet
(H.NJBaJpai and C,S.P.Iyer)
Zirconium oxide produced at NFC contains
sulphate as an impurity. A rapid and convenient spectrophoto-
metric method based on reduction of SO " to H2S (by Sn-H^PO )
and i t a reaction with p-aminodimethyl aniline in the presence
of PeClj to form methylene blue^ * has been developed.
The sample of ZrOg i s taken up in 8n-H5P04
and H9S is evolved by reduction of SO.". H 3 is remo-^ 2
ved from the reaction veasel by usiif: OOg as a carrier gas
and i s trapped in a solution of zino acetate* On acidifica-
t ion, H2S ia re-evolved and i s made to renct with
p-aminod4methylaniline in presence of PeOl^. Absorbance of
the methylene blue formed i s measured at 655 nm.
The SO?" content estimated by ueinf different
sample weights i s shown in Table 6.
1, T.Klba and I.Kiahi, Bull.Chem.Soo.Jaran, 20, 44 (1957).
-22-
TABLE 6
8peotrophotometrio determinationof sulphate in zirconium oxide
Wt. of ZrO2 Sulphate ex-(mgma) pressed as 8
ppm
10 890
20 890
30 900
1.2 (7) Turbidimetrio determination of traces of sulphatet
(S.ftanapathy Iyer , P.K.Fadmanabhan and H.R.Mulwani)
The method for the estimation of traces of
sulphate in water samples* ' has been extended to the ana-
l y s i s of sodium iodide, manganese ni trate and selenium
metal samples.
Sample solutions* Sodium iodidet t g
sodium iodide was dissolved i n water t o which few drops of
saturated asoorbio aoid so lut ion were added.
Manganese n i trate t The s a l t was oonrertad
to ohloride by repeated eTaporation with HOI,
Qeleniumi 1 g sample was dissolved in n i t r i o
aoid and selenium was removed by volata l iBat ion as i t s
bromide by treat ing with hydrobromio aoid.
- 2 3 -
Eatlmstlon of aulphatey An aliquot of the
sample solution In a 100 ml oonloal flask was made upto
10 ml with dis t i l led water. To this , 200 ug of sulphate
as feeding solution and 1 ml of the conditioning solu-
tion* ' were added. The solution w&e stirred (with a mag-
netic stirrer) for exactly 1 minute after adding 0.2 g
barium chloride. The absorbanoe of this solution was mea-
sured at 420 nm after 3 minutes and the sulphate oontent
read from a calibration graph ranging from 250-450 jag.
(1) Amcrioan Pub.Ho Health Association, 11th edition,
p.241.
1.2 (8) Sens! t l eat ion of, nioblum-bromopyro^al'.lol red
system by oefryltriroethylammonium bromide (CTAB)t.
(B.R.Billimoriat and S.G.Jadhav)
West et aV1^ developed a speotrophotonetrie
method for niobium using bromopyrogallol red (DPR) as a
oolorlmetrio reagent and gelatine as a sensitizier and sta-
b i l i s er . When OTAB was used as a colour sensitisier, the
molar extinction coefficient increased from 6.0 x 10
for gelatin to 2.0 x 105 In the present Case. The effect
of other metal Ions, on the colour reaction, wan also
studied* Calcium, barium, strontium, lead, arsenic (III)#
lanthanum, Bine, indium, magnesium, cerium, soandium,
- 2 4 -
thorium and mercury did not Interfere when present at 10
to 100 fold exceas, but most of the other coamon elements
Interfered with the oolour reaction. The interference of
Iron, copper, cobalt, nickel, cadmium, manganese, beryl-
lium and silver could be obvleted by oomplexing with
o-phenanthroline> Aluminium could be masked by fluoride
only when i t wae of the same order as niobium. In pre-
sence of 1-asoorbic acid and hydrogen peroxide, chromium
did not interfere* Hydrogen peroxide could be tolerated
4pto 1 mg in 100 ml. Beer's law was obeyed in the range
of 0.025 -0,100 ug ef NbgO /ml. Work is in progress to
apply this sensitive reaction to samples.
Procedure* To an aliquot of niobium solu-
tion prepared in 2$ tartario acid, 5*0 ml of 20$ ammonium
tartrate were added and the solution diluted to 30-4-0 ml.
5.0 ml of 2# 1-ascorbic aoid were then added, followed
by the addition of 2.5 ml of 0,2 M sodium fluoride, 5.0 a l
of 10?5 EDTA, 2.5 ml of 0.196 j-phenanthroline and 0.5 mg
of hydrogen peroxide**. The pH was adjusted to 4.5 ± 0.1
and the solution transferred to a 100 ml volume trio flask
containing 3.0 ml of O.O58J6 CTAB, and made upto volume.
After keeping the solutions overnight, absorption measure*
ments were made at 625 nm against the reagent blank.
• • The order of addition of reagents i s very important
1. T.T.Raraakriehna and T.S.West, Talanta, J£, 681 (1965).
-25-
1*2 (9) Pa termination of trapes of thorium in uranium
dioxide and uranium metalt
(H.Y.Joshi)
Normally traces of thorium in uranium dioxide
and metal fuels are determined by extracting the hulk of
uranium in TBP-keroaene mixture and precipitating thorium
in the aqueous phase as oxalate using lanthanum as a
carrier.
In the present method, the non-adsorbability
of thorium, especially at high acidities on a stron? anion
exchanger like Dowex-1, was employed to separate the element
tsom the hulk of uranium and other elements. A study of the
oehaviour of anions like fluoride and phosphate showed that
both these anions did net interfere in the elution of thorium.
Recoveries of thorium are given in Table 7.
The sample was dissolved in hydrochloric acid
with the aid of a few drops of hydrogen peroxide. The solu-
tion was loaded on a oolumn of Dowex-1 and thorium eluted
with 6 M hydrochloric aoid. Thorium in the effluent was
determined speotrophotometrically with thoron.
TABLE 7
Recovery of thorium added to thorium freeuranium metal
Uranium ThOg addes fsGg recoveredmetal pg
1 gm Nil Ril1 gin 50 521 gm 200 204
-26-
The method 1 B rapid and suitable for routine(1.)
work. The results compared with those by the TBP method
are given in Table 8.
TABLE 8
Thorium estimation by th«two methods
Present method TBP extract ionThO2 (ppm) method, ThOg (ppm)
?09 200
218 205
162 168
1. N.V.Thakur, R.V.Gokhale, L.M.Mahajan and S.M.Jogdeo,
BARO Report No.617 (1972).
1.3 ATOMIC ABSORPTION AND ATOMIC FLUORESCENCE
1.3 (1) Determination of iron r correr. nickel and cobalt
in RAPP orudst
(D.T.Randeria, P.Murujraiyan and Ch.Venkateswarlu)
The analysis of oruds i s important in corrosion
s tud ie s . The samples of cruds on mill lpore f i l t e r s received
from RAPP were dissolved in hydrochlorlo-hydrofluorio acid
mixture and fumed with sulphuric aoid. They were analysed
for f e , Cu, Hi, and Co by atomic absorption d i r e c t l y . Iron
was a l so determined by o-phenanthroline method and the values
are given below for comparison.
- 2 7 -
TABLE 9
Analysis of crude
Sample
E-2028
E-2029
B-2030
B-2031
E-2032
E-2033
E-2034
No* Pe by o-phenantbro-l ine method, jug
1690
415
625
335
445
1240
1110
by atomic absorption
Fe
1620
370
620
330
460
1270
1120
J
1.3 (2) Determination of oadmium in hijrti
ntomio fluorescence Bneotrophotometrys
Ou
50
20
75
60
40
50
35
purity
Ni
30
20
35
25
20
30
25
zinc I
Oo
20
20
20
20
20
20
20
(P.Mtirugaiyan, S.Natarajan and Ch.Yonkatsswarlu)
In continuation of the earlier studies on the
determination of oadmium by atomic fluorescence speotrophoto-
Eetry, the pcssibil ity of direot determination of oadmium in
eome high purity metals la being explored.
The equipment used and the operating condi-
tions have been described enrlier^1 ' . Al, Ca, Co, Or, Ou,
In;, Mn* Ugf Na, Ni, Tl, Zn and IT did not interfere at a
concentration level of 1 ng/ml . With a view to estimate
•28-
oadmiun at 1 pin level in high purity oopp»r, indium and sine,
the effeot of these elements on the fluorescence signal was
studied at a concentration level of 20;mg/ml and was found to
be negligible, She analytical results on Bine are given in
Table 10.
TABLE 10
Cadmium in tiao metal
Sample Cadmium()
Zn metal (from Hindus- 15.0
then Sine Ltd.*
Vaouum dist i l led sine 7.5
Sone refined zinc 0.8
1» P.Murugaiyan, S.Natarajan and Ch.Venkateawarlu,
MRO Report 1-187 (1972)
1«3 (3) Determination of zlno in high purity indium by
atomic fluorescence spfrfltrophotometryt* r
(P.Hurugaiyan, S.Natarajan and Oh.Venkateswarlu)
A Bine eleetrodeless discharge tube was
psepared by sealing 5 mg of zinc in quart* tube
(O.D. 8-10 mm, length 30-40 mm) at 3 torr, argon pres-
sure. A full scale fluoreecence signal at 2139 A was
observed when a solution containing 0.10 ng of Zn/al was
-29-
aspirated into air/aoetylene flame, A linear calibration
curve was obtained b«twe«n 0.01 - 0.10 jig of Zn/ml. The
effect of acidity was not studied since a l l the «,oids ware
found to oontain at least 0.1 ^g of Zn/ml of ooncentrated
aoid.
Indium metal was dissolved in analytical grade
HNOj or HOI and made up suitably to give a solution contain-
ing 10 nag of indium/ml, 0.5 M acidity and cine o on tent in the
above rang*. The same toid concentration was maintained in
standards to oorreot for the Zn oontent of the aoid. The
feasibi l i ty of the method for determination of Bino in high
purity indium was demonstrated by the standard addition tech-
nique. This method i s being extended to somei other high
purity metals.
TABU 11
Determination of aino in indium
Sample Zinc added Zino determi*(ppm) n*d, (ppm)
Zino reoo- Differencevered (ppm) (ppm)
B-1415
S-1416
1-1417
B-1418
or5o
o.lo0,40
0.902.0
0.401.25
0,380.83
O.160.350.53
1 ( > 1
ol"85
0.75
0*90.37
«»• 0 J 0
- o7i5
- otos
- OJ01- 0.03
1.3 (4) Boatterimr problea in the study of atomic fluoraacenoe
for cadmi1im>
(P.Murugaiyan and 8.HataraJan)
The determination of cadmium in zinc, copper
and indium metals has shown that the matrix elements do not
interfere even at a concentration level of 20 mg/ml. When
the AF8 method was used for the determination of cadmium in
rook-phosphate, the flu ores oenoe signal was found to be high
even with sample solutions freed from cadmium. 5 mg of Oa
or P0,/ml individually gave very low Bignals. But 10 mg of
calcium phosphate/ml gave about 10 times higher signal
(Sable 12). This aprears to be due to the scattering by
refractory particles of calcium oompounda formed in the flame
and i s not reduced by elements like Sr or La which are effeo-
tively used as releasing agents in atomic absorption methods.
The phenomenon i s under further investigation.
TABLE 12
Scattering effects in the atomio fluo-rescence analysis of cadmium
Solution Signal in divi -sions
0.1 ig Cd/ial 100
5 mg Oa/ml 2.0
5 mg P04/ml .. • o.5
(5 mg 0a + 5 mg PO^/ml 22
(5 mg Ca • 5 mg P0+ + 5 fflg Li)/ml 20
(5 mg 0a + 5 mg P04 + 5 mg La)/ml 29
(5 mg Oa + 5 mg P04 + 5 mg Sr)/ml 29(5 mg Oa + 5 mg P04» 5 mg Al)/ml 25
- 3 1 -
1,4 ELECTROAHALYTICAL AND OTHER MEM1ODS
1.4 (1) Determination of Impurities i n nuclear grade 8odium
by str ipping analysis*
(K.A.Khasgiwale, M.M.Mehta and M.Sundaresan)
Importance of sodium metal as a coolant in
certa in types of atomic reactors i s we l l known. -During the
operational period, impurit ies in sodium and those l iberated
due t o corrosion of s tructural materials e spec ia l ly iron,
cobal t , n i c k e l , e t c . , are subjected t o i rradiat ion , l a s
shutdown period i s l arge ly governed by the concentrations
of these impurit ies e s p e c i a l l y cobal t ' . S imi lar ly , other
i m p u r i t i e s , l i k e cadmium, lead, and s i n c e r e to be separated
and analysed by aqueous method as these impurities ge t
d i s t i l l e d off at the time of separation of bulk sodium by
d i s t i l l a t i o n under vaouum. Shain* ' has used anodic s t r i p -
ping polarography with preooncentration (stripping analys i s )
for the determination of cobalt i n pyridine-phosphate
medium. The same technique has been extended to the deter-
mination of impurit ies i n sodium.
Sodium metal was care fu l ly d isso lved in
water under inert atmosphere and the resul t ing sodium
hydroxide neutral i sed to give sodium chloride s o l u t i o n .
In pyrifline-pnospnate buffer the rwduotion of ions l ike
coba7t, n ieke l ana eino i s nearly revers ible and l a nuitable
for s tr ipping a n a l y s i s . Hiokel reduction potent ia l was
-32-
less oathodio and hence was eeparated from «that of cobalt.
Other iona like Bine, cadmium, lead were reduced at widely
separated potentials and could be analysed without inter-
ference of one another. These ione could be determined at
1 ppm level with a precision of ± 7#. Some results have
been given in Table 13 and typical ourves shown in 7ig.IV,
TABIB 13
Volume of the solution
pH of the solution
Preleotrolysis potential
Pre-electrolysis time
I?sat time
Anodic voltage sweep rate
Indicator electrode
Area of the electrode drop
Auxiliary electrode
Reference eleotrode
Supporting electrolyte
t 25 ml
i 6.00
» -1.2 V vs. 8CE
s 1 to 2 minutes
i 1 minute
i 0.050 V/sec.
t Hanging mercury electrode2
i 1.38 + 0.04 mm
j Platinum wire
i Saturated calomel» 0.05 M pyridine + 0.11 M
phosphate buffer
Blank oorreoted peak values I concentration 0.06 /ig/ral
Ion
Co2+
?bCd:
Zn:
2+
Peak
.0^ i
heightamp)
.130
.0360.C720 .140
-33-
1»4 (2) Determination of copper, oobalt and nickel }n
elect jbo-depoialta t
(T.P.Radhakrishnan and A.E.Sundaram)
A rapid method for the determination of
copper, cobalt and nickel in solution was required by the
Electrometallurgy Section of Metallurgy Division. A pola-
rographic method was developed using pure dist i l led pyridine
and pyridine hydrochloride as the supporting electrolyte^ ,
the composition being 0.25 M pyridine, 0.25 M pyridine hydro-
chloride and 0,08£ Triton X-100 as the maximum suppressor.
The solutions were deoxygenated and the diffusion currents
were measured at - 0.55 Vf - 0.95 V and - 1.20 V vs. SCE
for copper, nickel and cobalt respectively. A preliminary
separation of copper by precipitation with pure aluminium
metal »as necessary when the copper content of the sample
was mere than five times that of cobalt.
1. J.J.Lingone and H.Kerlinger, Ind.Eng.Chem.Anal.Ed.,
J l , 77 (1941).
1.4 (3) Estimation of cadmium in silver chloride crystals!
(Smt. J.S.Chaehoor and T.P.Radhakrishnan)
The Particle Detector Reoeareh Group of
TIIS was interested in the determination of traces of cad-
mium in silver ohloride einfle c/yntnls "9 e d l n emulsion
traok detectors. I t wao noceonrucy to analyse thia sections
of the oryatal lux' the cadmium impurity to assess the
concentration profile of the dopant diffused into the
matrix.
A polarographic method was developed using
a supporting electrolyte consisting of 2 M potassium chlo-
ride, 1 M hydrochloric acid and 0.01 per cent gelatin. The
silver chloride crystal was dissolved in ammonia and the
solution evaporated to dryness. The residue was shaken with
10 ml of the supporting electrolyte and the supernatant
liquid was transferred to a polarographic cel l , deoxygenated
and polarofraphed. The diffusion current was measured at
- 0.6 and 0.8 V vs. SCE and the cadmium content was obtained
by referring to a standard graph.
1.4 (4) Determination of corper and magnesium in Ou-Be-Mgr
alloys by oomplexometry;
(N.Kahadevan and R.M.Sathe)
Where suitable netallochromic indicators are
not available, end points in ccnplexometric t i t rat ion can be
located by a potentiometric method using a Hg/Hg EDTA elec-
trode. Such a method was successfully adopted f.or the deter-
mination of copper and magnesium in Cu-Be-Mg alloys.
A nitr ic aoid solution of the sample was
brought to pH ~- 5,0 UBing' a sodium acetate buffer and copper
was titrated with SDTA. The end point was Indicated by a
large and sharp change in the potential. The pH of the
solution was then raised to ~» 9.5 With ammonium nitrate-
ammonia (Cl~ ions interfere) buffer after masking beryllium
with a slight excess of salicylic acid. The potential
-35-
for ths Ba^natiua and point la much smaller but large
enough to ba looatad with certainty.
¥ha analyses of aona synthetic alxturas
and thoae of aoae alloy aampl«a for thair magneaiun aontant
given in Tabla 14*
TABLE 14
(a) Analy»is of synthatio mixtures
Ro.
1.
2.
5.
4.
B«2 + takeniftg
10.00
5.00
3o00
10,00
2+Ou takenfflg
28.46
21.55
H.23
42.70
0u2+ foundmg
28.28
21.28
14.14
42.68
Mg2+ takenKg
6.99
4.89
5.50
6.99
Hg foundmg
7.05
4.94
3.56
7.01
Analysis of alloy samples
SamplaHo.
1348
1351
1352
Present Visual titratioa aftermethod B©*+ separation
1.30 1.49
3.97 3.80
1.06 1.28
-36-
1,4 (5) Determination of oomblned oarbon In
(M.yundareeanr 6.P*Awaetbl, H.S.Daae and S.S.Sawant)
A method has been standardised to determine
combined oarbon (present as carbonate and oarbido) In alumi-
nium metal. She metal sample was heated with 1«3 sulphuric
aoid (previously boiled and oooled) and the evolved gases
(methane and carbon dioxide) were swept by purified argon
gas through a trap containing molecular sieve whloh in turn
was oooled by a slurry of dry ioe in acetone. After ten
minutes, argon flow is discontinued and oxygen gas allowed
to flow in. At the game time the molecular sieve waa slowly
heated to 300*C to release the oarbonaoeous gasesa These
were swept through a copper oxide tube heated to 900*0, to
convert all oarbon containing gauea to carbon dloxid®, 00^
gas was separated from the main stream of oxygen gas by
is open tane-liquid air trap and then from moisture by a trep
oooled by dry ioe-aoetone slurry. The purified OOg gas was
expanded into a known volume and its pressure read on a diffe
rential oil manometer. From the measured pressure , volume
and temperature of OO2 gao, the content of oarbon was calcula-
ted. A typioal sample of aluminium metal gave a value of
128 ppm with a standard deviation cf ± 2.5 ppm.
-57-
2 , RS&2ARGH WORK
2.1 PHY8IOO0HEMI0AL IHVE8MGATIQH8 OX CO08DINAHOS OCMPOlWDS
2 . 1 . (1) Borne mixed complexes of lanthanide lonst
(8.Y.8hetty and R.M.Sathe)
(a) Potentiometrio studies
The work on the mixed complexes of lanthanide
ions was continued using hydroxy&thyl~ethylenediamlne t r i -
aoetio acid (HEDTA) ae a primary lipand in place of BETA,
EEDTA being a tr lbas io aoid foiMns neutral 1s 1 ohelates
with lanthanide ione* The aeoondary ligands were as before,
oxine, fh -ieopropyl tropolone (IM) and N-bensoyl-E-phenyl-
hydroxylamlne.
The utabi l i ty constants of the mixed complexes
with KELTA ae the primary ligand hava been found to be
higher than the corresponding ones with EDTA* This i s
understandable einoe in the former aase, the secondary ligaa*
has to combine with a neutral primary ohelate while in the
l a t t e r case , i t has to overcome the e leotrostat io repul-
sion of a uninegative BDTA complex. Amongst the seoondary
ll^andn, the order ot s t a b i l i t i e s was found to be «£!•«• >
IPT > BPHA. Tor suoh a ocshparison, however, i t Is f e l t
that a parameter l i t e log A/log I? ! would give a truer
picture . The s t a b i l i t y constant i s a resultant of a number
of parameters, the main one being the proton a f f in i ty
constant of the l igand. The relationship i s generally
-38-
K > log I" + b
5Fhe t*ra 'b* inoludea iresonano* or ^ bonding effsots
originally augge»t©d by Calvin and Wilaon* ' from their
•tudiea on 0u2+- beta diketon* ayotema. 8uoh eff*ota are
obvious) ly abaant in oomplexea of lanthanide ion* and the
ratio log K/log K? wil l hen jtold th« term 'a1 which can
be eanttidereii to inoluds faotors liico nature of bonding
Atesagi, ring alee and other staria effeota. ¥he oomparieon
of thia parameter (Table 15) ehowa an order I FT > Oxine>
BHiA and brings out olearly the preference of lanthanide
ions for oxygen donor a ao situated to form a five membered
ahelate ring,
As with mixed oomplexea of Ln -EDTA, the
Hlxed oomplexee of Gd5+ and X»u (half f i l led and oomplately
filled 4f ohell) with ITT and oxine were found to give s ig-
nificant molecular fluoreaoenoe. ?urth«r l ight on the eight
fold coordination of Xin'+ ion was thrown during the study
at i3d -DTFA and In -EOTA ayatema. When an ootadentate
llg«\nd like DTPA wae uaed no further combination with aeoon-
darv Uganda waa observed for Gd . So also a related t r i -
val«nii ion In5"*" after oombination with EDTA was aleo found to
\m incapable of further reaction with secondary Uganda ehow-
ing thereby that only the ±OL + iona can exhibit a coordinateim
eight.
and K.V.WllBon, J.Am.Gh»i»,Poo«,f £2* 2005 (1945)
-39-
TABLS 15
Log K/pK values for Vae mixed complexes of Ln -EDTA
Ligand
Oxine
/3 -isopropyl tropolone
N -bena oy 1 -N -phe nylhydroxylamine
Metalion
P r 3 +
Sm5+
Gd3+
Ho5*
Tm5+
Lu 3 +
P r 5 +
Gd5 +
H o ? +
Tm5 +
Lu3"1
H+
Sni3+
Gd3 +
Ho5 +
Tm'+
Lu5 +
log K
10.16
4.81
5.08
5.19
5.736.076,16
7.364.785.035.125.635.946.01
8.774.12
4.30
4.41
4.78
4.83
4.87
log
•
0.
0.
0.
0.
0 .
0<
0,
0,
0
0
0
0
0
0
0
0
0
0
K/pK
,.
.47
.50
.51
.56
,60
,61
- •
.65
.68
.70
.76
.81
.82
• *
.47
.49
.50
.55
.55
.56
-40-
(b) PolMrograpblo atudiest
Confirmation for the existenoe for these
mixed ooaplexes of Isathanide ions was obtained from polaro-
graphio data. Ths polarograms were reoorded on a Cambridge
recording polarograph. The half-wave potentials of Bu3* in
the two oomplexing media are given in Table 16. In a l l
oases, significant shifts of Bi towards a more negative poten-
t ia l have been observed in the presence of the secondary
Uganda. Here also, **hose for IPT are somewhat larger than
those for BFHA as i s expected from the higher stabi l i ty of
the former.
TABLE 16
Polarographio studies of the mixed oomplexes of Bu
Complex ion pH Ei
1 . Eu** + EDTA 8.00 - 1.18 Y
2. Eu5* + EDTA ••• /3-ieopropyltropolone 8.00 - 1.30 Y
3. Eu3* • EDTA 9.30 - 1.19 Y
4. Eu 3* + EDTA + H-ben»oyl-N-Phenyl- 9.30 - 1.27 Y
hydroxylamine
5. Bu3* • HEDTA 5.70 - 1.12 Y
6. Bu3* • BEDTA • fi -isopropyltropolone 6.00 - 1.32 Y
7. Bu3* • HEDTA 9.00 - 1.13 Y
ft. Bu** + HEDTA • I-bsnsoyl-I-phenyl- 9,00 - 1.20 Yhydroxylsmine
- 4 1 -
2.1 (2) Mixad oomplaxeB of Th*+i
(8.Y.8hatty and K.M.Sathe)
Potentio&etrio Investigations of nixed complex
systems hare now been extended to the rfh*+ ion, EDTA and
DTPA aarrad as primary Uganda, whilo oxine, gallic acid,
BESA and tiron were chosen as secondary ligands. A aat of
three t l teat ions was performed for eaoh system an follows?
(1) Th4**" + primary ligand ( 1 I 1 ) , ( i i ) free aoid in thorium
solution + aold liberated due to the formation of the pri-
mary complex + secondary llgand, ( i l l ) Th + primary
ligand + secondary ligand (11112) •
The reactions between the primary oomplex and
the secondary ligand oan be either an addition or substitu-
tion type, i .e . , there ia a likelihood of the secondary ligand
displacing and occupying positions previously held by the
coordinating atoms of the primary ligand, thus maintaining
the i n i t i a l coordination number. In such a situation, the
oarboxyl&te groups so set free would take up protons from
the system in the appropriate pH range and disturb the
proton balance. The sharp inflexions in titretion ourveo
correspond to complete liberation of equivalent protons
from the secondary ligand. confirming that the oomplex
foziBlng reactions are of the additive type.
The studies have further revealed that a
paliiaxy complex of Th** with a hexadentate ligand (BSTA)
-42-
oan combine wt th two moleoulee of e Mdentate aeoondary
ligend while that with an ootadentatc ligand (DTPA) oan
only taken up one extra moleoule of auoh a secondary ligand,
thereby indicating a tenfold coordination for the T\r* ion.
As in the oaee of lanthanide ions*1 , the mixed complexes of
the neutral primary fh-EDTA oosaplex exhibited higher stabi-
l i ty than the corresponding onea with aininegative Th«DTPA
complex.
1* 8.Y.Shetty, 0urr.8oi., £1, 675, (19T2).
2.1 (5) Theoretioal treatment for Job'u method of o.v.
under differant oondltionai
(F.8 .Ramanathan)
Baaed on Lagrange'a method of undetermined
multipliers, the following mathematical derivations have
been arrived at ,
(i) A general solution for continuous varia-
tion experiment for the case of a single mixed complex oon-
taining any number of Uganda (M A Bt Zn) has been
arrived at. I t la shown that the ratio of the total concen-
trations of the reaotants in the mixture having maximum con-
centration of the mixed oomplex in a o.v. experiment, will
be the same ae stolon!ometry of the mixed oomplex.
- 4 3 -
( i l ) She following expresoion has been
derived for Tlaa3C obtained in the o.v. method in non-
tojainolar solutionsu
In tii* above equation, T 1B the value ofvolume of l i Sg
T(volume of metal I volume of ligand* i n t h # « o l u t i ° n
In which the concentration of the complex I X (assumed
to be formed exoluelvely In a l l the solutlona) hat) the
maximum value, o and po are the oonoentratloni of the
Kftt l and llgand aolutlone ueed (p ^ 1) nzxd Qffl the
maximum ooncontratlon of M_Ap In the non-equimolar set.
Jhe f lret term on the right hand side represent a the vmaJt
expeoted in th«i o.v. method in equimolar eolutlone
(r/ q+r) whioh- i e Independent of K, the formation constant
of the complex). The aeoond term ie then the deviation
from thle value owing to the use of con-oquimolar reao-
tant solutions* I t reflects the dependence of VmBX <>n Kthrough Q,,.^ in the numerator. Two graphical prooeduree
m&A
have been proposed, based on the above equation, to arrive
at the oomposit.on of a binary complex.
( I l l ) Th* values of x [OA/ (°M+OA)1 w h i o h
ocrreepcDd to the maximum concentration of MA, MAgand
BULj separately when th« o.v. nothod Is applied to a system
in whioh a l l the three aooplexes fona simultaneouely In
a l l the solutions, have been arrived at. The final
equ&tlona obtained aret
-44-
x (corresponding to the 1i1 complex)max
0.50 (CA)
(C A) Q • Q 2 + 3Q,
(corresponding to the 112 complex)
0.67 ( 0 A ) o
TO_(oorresponding to the 1*3 complex)ma*
0.75
(C A) 0 - 0.5
In these equations (°A)0» Qjt Qg and Q3
represent the concentrations of A, MA, MA£ and MA*
respectively in the solution in which the concentration
of the complex under consideration ia maximum. The
xmax for the 1|1 ie *ound to get shifted to a value
< 0.50 by MA« and MA*. MA tends to shift the xc •> max
for the t»2 to a value higher than O.67 while MA?
brings about the reverse e f f e c t . Dhe observed xmax
will, therefore, depend upon the relative concentrationsof MA and MA, in the solution in which Qo « (Qo)
•' c. c. m a x
The x^^^ for the 1 s3 gets shifted to a value > 0.75 due
the influence of MA and MA2.
-45-
Sheee expreaaiona are la agreement with thoae
atsln and Gebert'1' and Watk
by using different mathematical procedure*.
arrived at by Xatsln and Gebert'1' and Watkine and
1. L.I.Katsin and E.Gebert, J.Am.Ohem.Soc, 22.i 5455 (1950)/
2* K.O.Watkina and M.M. Jones, J.Inorg.Huol.Ohem., 24,, 1607,
(1962).
2,1 (4) Spectrophotometry of the indlum-bromopyrogallol
red (BPR) eyatemt
(8.6.Jadhav, P.Murugaiyan and Oh.Tenkateewarlu)
The indiuB-BPR eyatem haa been atudled in
the presence and abaeno« of ammonium aoetate as alao in
water-alsohol medium. I t appeara that in a l l the oaaea,
the 1)1 complex exists predominantly around pH 4*0 and
the higher complex (1i2) predominatea above pH 6.0. 1
1i3 complex la not detooted evan at pH 9*0, contaary to
tha report of I ts formation at pH 5.0^1'. Only polar
advents Ilka nitrobansena, butanol and beneyl aloohol
extracted a ooloured complex from thia aystem at pH 6.0 «
9.0. Among tha above mentioned aolvents, bensyl aloohol
wae selaoted for further work. The composition of tha
extracted speoiea, irresipeotive of yHs wao found to be
1i2 with respect to metal and dye, Beer'u law wae obeyed
for 0.75 - 1.50 jug of indi\«n/tal ft* pH 6.5 aa well aa
pH 9.0.
-46-
To determine Indium in sino and sino base
alloys at 5 ppa level , interference of a few elements,
including the matrix element, sine, was studied. Cyanide
was able to mask sino ceily at pH 9.0. In the presence of
oyanide, nine, iron, oopper, cobalt, nickel and cadmium
did not interfere at 30 jug/ml level . In the presenoe of
fluoride, gallium could be tolerated upto 0.3 jag/ml,
but aluminium oontinued to interfere* Hence, i t was
neoeseary to separate indium, from zinc and other elements
using isopropyl ether extraction from hydrovromio add(2)mediumv ' prior to i t s determination by'the present
method. A few sine samples were analysed by the method
(with standard additions) and the results obtained have
been oompared with those by oxine extraction method
(Table 17).
1. P.P.Kish, Hauk, Zap. tfahgorodsk Univ., ££, 70 (1962)
2. I.A.Collins and J.H.Kanselneyer, Anal.Ohem., 3_3_, 245,(1961).
- 47 -
TABLE 17
Determination of indivja in sine
(Weight of sample taken - 1 g)
SampleNo
A
B
»
it
Indium added
• •
to.o15.0
Indium found
oxine me- Presentthod method
22.8* 22.84-
15.0
25.0
30.5
* Average of three values
+ Average of eleven values
2.1 (9) Study of mixed complexes by solvent extraction:
(M.Sudersanan and A.K.Sundaram)
Study of mixed complexes by the method of
solvent extraction has generally been confined to the
adduot formation of metals with beta dilcetonea and neutral
organophosphorous esters . This phenomenon, called syner-
gism, has attraoted considerable Interest in recent years.
Another type of mixed complexes involves the formation of
mixed chelatee. A study of mixed complex formation of
indium with some beta dikatones in bensene medium has been
carried out.
-48-
The distribution coefficients p ^ of
benzoylacetone (BA), dibensoyl methane (DBM), benaoyl
trlfluoroacetone (BFA) and furoyltrifluoroaeetone (FFA)
between 0.1 M eodium perchlorete and benaene were deter-
mined. The final concentration of the extracting agent,
FFA, in the organie phase m e calculated taking into
account its distribution ratio ft determined in a sepa-
rate series of experiments. In other cases, the distri-
bution ratio was high enough to neglect the correction
factor.
The extraction of indium by the beta
dike-tones was studied as a function of pH and the con-
centration of the ligand. The plot of log D vs . pH
resulted in a straight line of slope three indicating
the extraction of In3* in the organic phase. The extrao
tion oonstants (Table 18) decreased in the order
PPA> BPA> BA — DBM.
In the presence of another chelating
agent, HB, the distribution of indium can be written in
terms of the equilibrium constant as
The extraction of indium in the presenoe
of tiro chelatlnp apents was studied and the equilibrium
constants w-:•*•>-• ol«tnined by a graphical solution of the
aboveejuatlon (Table 19). The value of K5Q obtained from
-49-
data on mixed complexes agreed with that in the oast of
tht binary metal-ligand system. The complexes art sta-
bilised in moat oases and tht ttabiliaatioa oonatant^
fox BA and DEM art alaoat tht a ant indicating a rela-
tionship lotwttn log E ( - log Ka + log 3.0) and A log E
of tht parent oonpltacta.
1. T.Merous and I.Slleeer, 0oor.0htm.Rev., £1., 273 (1969)
TABLE 18
Sxtraotion of indium
Btta diketon* pK log Pn* - 1°« *
Bansoyl aoatontDlbons oy lms thane
Btnsoyltrifluoro aottone
Fur oyl tri f luor oao 11 ont
8.8
9.35
6.30
5.87
2.79
5.35
2.0
1.0
6
e3
2
•36
.57
.66
.04
w
-50-
TABLB 19
Extraction oonatants
- log Equilibrium - log etatia- • log aixing • log etabioonetant oal stability constant, EL. lig&ticn
oonatant oonetant,
Indlun-BA-BFA-bensenet
K03K12
6.364.523.773.65
Indium-DBM-BFA-b»n*«n«t
*03
01
•so
6.574.703.773.62
I ndiua-BPA -FFA-benxene i
K03K12K2tK30
3.662.572.392.04
Indiua-BA-ZFA-bensene t
^03KiaK21*30
6.363.902.802.05
Indluffl-DBM-FlA-benBenei
K03K12
6.434.302.982.05
. .4.984,08
•.5.114.13
. .2.642.10
? ,
4.443.00
• *4.443.02
••
0,960.79
. ,0.890.84
. .0.550.19
. .
1.020.68
•.0.666.52
••
0.460.31
. .
0.410.56
. ,0.07
-0.29
6.540.20
0.140.04
••
-51-
2.1 (6) Study of complex formation by competitive reactions!!
(a) 61:rcollatet mandelate and tfaloglvcolate oomplexeai
of indiumi
(M.Buderaanan and A.K.Stmdaran)
Solvent extraction has been ueed for the
study of complex formation by competitive reactions. The
applicability of the rigorous method' ' for the calculation
of the -stability constants has been checked in a few
cases' * '. The results on the study of indium complexes
with glyoollio and mandel11o acids are presented here.
The extraction of indium by thenoyltrifluoro-
aoetone (HTTA) in beneene was studied in detail.]A plot
of log p vs. log TTA gave a straight line with a slope of
three, indicating extraction of the complex In(TTA)5. The
extraction was studied at varying concentrations of glyool-
lio or mandello acid it the aqueous phase. The concentra-
tion of glyoollate or mandelate ions was calculated from
the pH and pK value of the corresponding aoid. The pi
values in the presence of 1.0 H sodium peroh"! orate, were
detemined in a separate series of experiments by pH
titrations.
The extraction of indium in the presence of
the eomplexing Uganda deoreaoed indicating the preaenoe of
tbxee indium complexes in the aqueous phase. The nature of
the complexes and their stability constants were determined
-52-
using the graphical extrapolation method and th« values
are reported In Table 20.
With thioglyeollic acid, the extraction of Indies
Is masked even at the lowest concentration of the ligand
and high pH. Hence the oomplexees of indium with thioglyool-
l io aold oouid not be identified nor could their s tabi l i t ies
be calculated.
1. M.Sudersanan and A.K.Sundaraa, Proo. Ind.Aoad.8oi.,
2£, 1 (1971).
2. M.Sudersanan and A.K.Sundaram, ibid, Jl* 151 (1972)
3. M.Sudersanan and A.S.Sundarao, 0urr.8oi. (under
publication).
TABLE 20
Stability constants for indium complexes
aiyoollio aoid complexes Mandelio aoid complexes
3.0
2.9
5.4
pK
log j
log /
log
^11 2
'"* 3
3.303.76
6.30
8.70
-53-
(b) Study of some sino oomplexesg
(Pushparaja*, H.Sudersanan and A.K.Sundaram)
Solvent extraction technique has been used for
the study of sine oomplexee with oxalaief tartarate and
glyoollate by the method of competitive oomrlex formation.
Thenoyltrifluoroacetone was used as the auxiliary ligand.
The partition coefficient and the stabil i ty con-
atants of cino-TTA system were obtained by the graphical
method of Rydberg. The change in the distribution ratio
of Bino-TTA measured in the presence of the primary COB-
plexing agents was utilised for the determination of the
stabil i ty oonetents of the various species (Table 21).
1. 0.Warren, Vosburgh and J.F.Beokwan, J.Amer.Chem.Soo
62, 1028 (1940).
2. Y.Prei and J.Ioub, Z.Phy.Chem., 222, 249 (1963).
3. A.Liberti, P.Ourro and G.Oalabro, Rioeroa Soi., 3J»
36 (1963).
• Health Physics Division.
-54 -
TABLE 21
8tabil lV constants of sino omplezes
Oxalate Tartrate OlyoollatePresent Lit«tfa- PresentLitera- Present Litera-study tureO) study turel*'- etufly ture(3)
value value value
log P- 1 3,26 . . 5.76 3*09 1.85 1.92
log P 2 6.63 7.36 . . . . 3.32 2.93
log p-j . . . . . . . . 3.38 3.00
Zn-TTA complexes (aoueoua phase)
log P-,t 2.4; log f 2 : T.O
2.1 (7) Polarography of blemuthi
(S.Sundaresan and A.K.Sundaram)
Bismuth gives a fairly well defined wave in 1.0 M
potaasium nitrate with the half-wave potential at +0.021 V
va. SCB. The presence of & smell maximum oould be oonve-
niently rounded off without affecting the half-wave poten-
t i a l . A maximum eupiressor was therefore not necessary.
No measurements oowld be made on bismuth-
thiourea extern as thiourea i t s e l f depolarised meroury
at about -0.1 V vs. SOE. This ouggeeted the preaenoe of
weak complexes * This la in accordance with the findings of
Vasil'ev and Greohina^1^ but in variance with Swaminathan(2)
and Irving , who have reported log Pg for the system as
9.3.
-55 -
Folarograms of bismuth in potaiaslum nitrate medium
were obtained at different oonoentrations of oxalate at
abput pH 6.0. The waves were well defined but were irrever-
sible in nature. Hence the formal potentials were obtained
from composite waves and the kinetic parameters, oC and k,
were calculated by the methods described earlier* '
(Table 22). The stabi l i ty constants were calculated by the
method of Deford and Humev ' using formal potentials and
the values aret p^ * 6,0x10 , /3g « 5.5x1O1*,
- 2.7x1O15g p4 « 3.1x1O16 and f*5 - 1.9x1017.
An attempt waa made to study ths mixed complexes
of bismuth with thiourea and oxalate. Poaarograms were
obtained in the presence of a constant concentration of
thiourea and varying amounts of oxalate. The log-plots
were curved indicating the quasi-reversible nature of the
reduotlon. The half wave potential (Table 22) at any con-
centration of oxalate was coratant at different concentration
of thiourea. The reduction also occurred at more positive
potentials than in the absence of thiourea indicating that
the presence of thiourea makes the reduction ntore reversible.
In the absence of any oiixed complex formation,
the formal potentials obtained in the presence and absanoe
of thiourea should have been the same. The observed dis-
crepancy between the two values could mean that thiourea
TO
0.02
0.04
0.10
OX
0.080.12
0.240.32.
0.040.08
0.12
0.16
0,240.32
0.080.16
0.32
0.40
0.50
Kinetic
TABIE
data for the reductionof ozalate and
V
0.2370.256
0.2800.288
0.222
0.244
0.2550.270
0.2790.290
0.2420.262
0.288
0.220
0.2350.2580.266
0.201
0.224
0.235
0.2490.260
0.226
0.254
0.269
thiourea
22
of bissuth
Hale and Parsons 1
0.61
0.590.640.62
0.580.62
0.60
0.530.61
0.590.62
0.60
V10*5.43.53.0
3.2
2.6
3.93.94.03.7
5*0
3.2
in the
Si(HJ-O)
..
..
..
0.291
0.3150.321
0.3340.342
0.352
presence
I Amalgam
Bj(WJ-O)
0.240
0.250
0.2700.276
0.221
0.257
0.289
0.289
polarography
0.51
0.48
0.44
K.X10*
3.4
3.1
4.3
i
Grl
l
potentials are -V VB. SCE
-57-
besides aeoelerating the electrode reaotion alao shifts
the reduction potential to a more positive value. Thia
could not be confirmed by amalgam polarography BB compo-
aite polarograme could not be obtained in the preaewoe of
thiourea?
1. V.P.Vasil'ev and K.K.Greohina, RuoB.JMnorg.Oheia.,
12, 823 (1967).
2. K.Swaminathan and H.Irving, J.InorgeNuol,Ghent., 2,8,
171, (1966).
5. VJl.Ohandraaefcharan, R.Sundareoan, S.O.Saraiya and
f9?.Re.dhakriatman, BARO Report So,370 (1968).
4. B.D.Be Ford and D.N.Hume, J.Am.0hem.8oo,, 22* 5521
(1951).
2.1 (8) Polarographio raduotion of Ti (IV) with
galioylio acid as supporting electrolyte in aqueous
mixtures of methanoli
(R.G.Shaneahwar and D.P.Pitaputkar*)
I t WM observed that in MBO, the half-wnv*
potentiala were found to be oMfted towards negative side for
a l l pH valued1^. Tho hsilf wave potential* and difftteton
curranta for 0.5 mM Ti (IY) solution In 0,1 M aulpho»alioylio
* Health Physics Pivlelon
-58-
aold supporting electrolyte in different aqueous mixtures
of methanol at different pH, are given in Table 23. At
pH 1 and 2, aa the percentage of methanol i s increased, the
half wave potentials are found to shift towards negative
side with increasing methanol concentration indicating that
solvolysls rather than the suppression of hydrolysis i s
of prime importance at these pH values. However, at higher
pH values the shift in the half wave potential i s tovards
the positive side with increasing methanol concentration,
so that hydrolysis of Ti (IV) Besme to be suppressed to BOSS
extent. The negative and positive shifts are small. This
i s to be expected, sinoe methanol and water are similar to
eaoL ether in structure. The results show that at higher
pH, the suppression of hydrolysis occurs with methanol,
but not with DM80.
At different pH valueB in aqueous solution, two
waves are obtained. In 50# methanol solutions at pH 6,
7 and 3, both the waves are obtained. At pH 5, both th»
curves are obtained upto 20£ methanol, at pH 4.0 , 10^
methanol and at pH 2, 40# nsethanol. At pE 1 and 8, only a
single curve is obtained in water and the mixed solvent.
The curves obtained at pH2 are shown in Pig. V, The
reasons for the disappearance of the second wave for the
intermediate pH range at higher percentages of methanol are
under investigation.
-59-
TABLE 23
Ti (IV) reflection In different aqueouemixtures of methanol a t different pH
Sulphosalioyllo acid • 0.1 lit Ti (IV) » 0.5 mM
No.
1.2.3.
4.
5.6.
7.
8.
9.10,
11.
12.
13.
14.
15.
16.
17.
pH
1.01.02.0
2,0
2.03.0
3.0
4.0
4.05.0
5.06.0
6.0
7.0
7.0
8.08.0
i» methanol
Nil60Nil
30
50Nil
50
Nil
50Hil
50Hll
50
Nil
50
Nil40
1hV
-0-0
-0-0
-0-0-0
-0-1-0-1-0-1-1-0-1-1
-0-1-1-1
-0-1-1-1
-1
-1
.335
.350
.500
.800
.540
.780
.550
.840
.190
.670
.160
.840
.180
.160
.860
.200
.10
,880.420
.160
.500
.900
.480
.150
.460
.460
.450
}iJIsIIji!
fx amp
0.70
0.61
0.61
0.45
0.300.86
0.32
0.58
0.36
0.72
0.39
C.70
0.39
0.68
0.50
0.58
0.45
Brackets indicate double waves.
-60-
?or al l pH values, with increasing methanol
concentration, the total diffusion current deoreases by
50-40^. Whenever two waves are present, the height of
the f irst wave increases and that of the seoond wave dec-
reases, thue clearly showing that f irst hydrolysed
species^ ' becomes predominant compared to the second
hydrolysed species with increasing methanol concentration.
The eurrent-conoentration linearity was observed
for a l l pH values and for a l l methanol concentrations.
A plot of current vs . the square root of the mercury reser*
voir height indicated that the current was diffusion con-
trolled under the diverse experimental conditions. The
reversibility of the electrode reaotion was tested by the
usual conventional methods and was found to be so in
almost a l l the eleotrode reactions.
A Cambridge recording polarograph along with
eleotrode system was used in the present work*
1. Annual Report, Analytical Chemistry Division, BARC-639,
p.66 (1971).
2. L.R.Zarapkar, M.So Thesis, "Polarographic studies of
titanium (IV) reduction in aromatic hydroxy acids1*,
University of Bombay, (1970).
2.1 (9) Polarograuhy of Indium In laotlo and glycollic
aold medlai
(Puehparaja*, H.Sudersanan and A.K.Sundaram)
Oomplezes of indium are of general Importance
and nave been studied by various methods* Complexes of
indium with several Uganda have been studied in these
laboratories by the method of solvent extraction. In con-
tinuation of this work f the results on the above systems
by a polarographio method are reported here.
Polarograms of indium were obtained at different
pH values in the presenoe of glyoollio/laotio acids. The
slope of the log-plot indioated a reversible deduction.
This was oonflxmed in the oase of indium-glyoollio aold
system from the formal potentials meas Tsd from ocatposite
waves* The plot of £< vs. log l&otate/glyoollate ion
oonoentration indioated the presence of several complexes
and the stability oonstants were oaloulated by the method
of DeFord and Hume* The values are listed in Table 24.
The agreement with the values obtained by solvent extrac-
tion i s good.
Health Physios Division.
-62-
TABLE 24
Stability constants of indium eomplexes
log stability Polarography Solvent extraotionconstant
P>3
laotate
3.30
6.31
7.68
glyoollate
3.48
6.30
8.36
laotate
3.2
6.3
8.2
glyoollate
3.76
6.30
8.70
2.1 (10) Polarography of indium in thioglvoollio acid mediums
(S.A.Yajnik and A.K.Sundaram)
In continuation of our studies of indium complexes
by different physicochemical techniques, the polaropraphic
behaviour of indium in thioglycollio aoid was investigated.
Polarograms of indium were obtained in the presence
of thioglyoollio aoid at different pH values. The concen-
tration of the free ligand was calculated from the pH and
pK value of the ligand. A well defined wave was obtained
and the slope of the log-plots indioated in irreversible
reduction. It was however observed that the formal poten-
t ia l s obtained from the composite waves were identioal with
the half-wave potentials. The stabil i ty constants were oal-
oulated by the method of DePord and Hume and the values arei
P2 - LOxiO7, |3j - 8.5X1010, p4 - 6.0x1012, ana
p 5 - 5.0x1014.
-63-
2.1 (11) Thencochemical atid infrared studies of some
benzoateei
(E.L.Jangida, R.S.Daas and M.Sundaresan)
The heats of formation of caloium and thorium
benzoatea have been determined using a bomb calorimeter*
The vapour pressures of these compounds and the thermodyna-
mio properties associated with their sublimation processes
have been determined using an oi l isoteniscope. The mean
bond energies of Ca-0 and Th-0 bonds have been calculated
by devising suitable empirical Bom-Haber oyoles and these
agreed well with those reported In literature. Depending
upon these bond energies, probable structures are being
assigned to these compounds*
These structures have been further checked by
infrared studies of these oompounda along with magnesium
benzoate for which the Mg-0 bond energy has been previously
reported from this laboratory^ ' . The infrared spectra
for sodium, magnesium, calcium and thorium bensoates in
the range 4000-250 cm" were recorded. The water band
was oompletely absent in a l l the four compounds showing that
water waa removed on heating at 150*0 in vaouum. While
the characteristic frequencies of COOH group disappeared,
the i> 000 and ^,000 frequencies ocoured at aboutex 9
1600 om"*1(VS) and 1420 cm*"1 (VS) respectively for a l l the
-64-
„. ffour benaoates. In the lower region, 650-250 om ,
magnesium benzoate shoved a shift towards higher fre-
quency at 476 cm"1 (broad band) for Mg-0 stretching oco-
pared to the absorption frequency at 400 om" (a) for
sodium benzoate. This oonfirmed that Mg-0 band has a
ooordinate link unlike the ionic Na-0 bend. The studies
for oaloium and thorium benaoatea in this region of the
Infrared are being undertaken.
1, D.B.Trivedi, HI.So Thesis, University of Bombay, (1968).
2*1 (12) Thermoohemical studies on glno chelatest
(N.P.Bhat, S.S.Shinde* and M.Sundaresan)
In continuation of our thermochemical studies on
coordination compounds, a number of Kinc ohelates have been
investigated. Two groups of oompounds have been selected,
one group containing purely metal-oxygen bonds and the
other group containing both metal-oxygen and metal-nitrogen
bonds. In the first group, three compounds of zino with
aoetylaoetone, benzoyl acetone and dibenzoyl methane res-
pectively have been prepared. In th« second group, oom-
pounds of eino with 8-hydroxy quinoline, 8-hydro3ey
quinaldine, quinaldinio acid and anthranilio acid have
• Fuel Reprocessing Division, BARO,
- 6 5 -
been prepared. All the compounds have been tested for
their purity by su i table metal ana lys i s . The heats of
combustion of some of the compounds have been determined
in a s t a t i c bomb calorimeter, and heats of formation have
been calculated (Table 2 5 ) . The vapour pressures of
these compounds at d i f f erent temperatures are being deter-
mined with an ieoteniaoopio set up. This data would
f ina l ly lead to the ca lculat ion of bond energies of s i n o -
oxygen and eino-nitrogen bonds in these compounds.
TABLE 25
Heats of combustion and heats of formation
(K cal/mole)
Compound - A Ho "*AHf
1. Zino-acetylacetonate 1162 339.8
2. Zino-8-hydroxyquinoIate 1927 258.9
5. Zino-8-hydroxyquinaldinate 2309 2CT.6
4 . Zinc-anthranilate 1629 180.7
2«1 (13) Thermochemistry of metal-sulphur bonded coordi-
nation compoundst
(K.P.Bnat and M.Sundaresan)
Stat ic bomb calorimetry has been used by previous
workers i n the determination of heats of combustion of
coordination compounds and the data has been used In the
calculat ion of metal-oxygen end metal-nitrogen bond
- b b -
energies. To obtain well defined reaction products, rotating
bomb calorimetry had to be used in the heats of combustion
studies of organohalogen or organosulphur compounds, but
no coordination compound has been studied by th i s technique
BO fa r . . The present work was in i t i a ted to determine the
heats of combustion of coordination compounds containing
sulphur by rotating bomb oalorimetry and t.o determine the
metal-sulphur bond energies in metal o he late a of t hi odi ace-
t ic and dittoocarbazie acids. Thiodiacetic acid was synthe-(A)
Bised from monochloroacetio acid and mercaptoacetlc a c i d * .Hydraslnium dithiocarbazate was prepared from carbon disul-
(5)prdds and hydrazine hydrate* ' . I n i t i a l l y three compounds
v iz . , copper and nickel thiodiacetates and niokel d i th io-
oarbazate have been prepared. All the compounds were t e s -
ted for purity by suitable metal and sulphur analysis . Heats
of oombustion of oopper thiodiacetate, nickel dithiocarbazate
and the respective chelates have been determined in a bomb
calorimeter specially fabricated in this laboratory. Heats
of solution of copper and nickel thiodiacetates, thiodiacetic
acid and hydrazinium dithiocarbazate were measured in an
isoperibol calorimeter. Heats of formation have been calcula-
ted for a l l these compounds and the ohelates. By applying a
modified form of Born-Haber oycle^1 ' and borrowing related
thermochemical value from l i t e r a tu r e , the toeats of chelation
in the gaseous phase and bond energies of metal-sulphur bonds
have been calculated.
?ABLB 26
ffcexnocfaemlcal data for metal-sulphur bondedocapounds
Ooapound
1. Thiodlacetle aeid
2. Hydraslnlua dlthlocarbasate
3. Bltbloearbasle add
4. Copper thlodlaeettate
5. Hickel thlodlacet&te
6. Blekel dithiooarbasate
Bondenergy
-341.6
-392.6
-326.7
-402.5
sea6
3
1
7
I/sole.99
.68
.60
.83
-239.5
25.4
20.9
-209.5-218.7
-255.6
-219.1
-56
-117
-226
.1
.7
. 8
15.9(Cu-S)
91.1(Si-S)
86.9(Hi-S)
-JI
-68-
In the case of thlodiaoetates» the assumption
of bonding through oarboxylate groups onjly( structure I)
would lead to very high Hi-0 and Cu-0 bond energies, i . e . ,
117.3 and 86.5 KOal/mole respectively as against 71*8 and
48.7 KOal/aole reported earlier*1 » 2 ' . I t can therefore
be safely assumed that the metal ion i s bonded tc sul-
phur. Shis would also lead to a suitable ring s ine. The
58-8 bond energy was therefore calculated by assuming
struoture II and employing the reported M-0 bond energies.
0H2
(I) (II)
^.8
' . 8 HpHNH—of VL fUNHH—0^
N ^ \' 2 N8.
(Ill) (IV) (V)
The bond energy of Hi-a bond has been calculated assuming
structure III . This value is in agreement with the Bi-S
bond value in thiodiacetate* Structures II and III have
also been supported by infrared studies of
-69 -
and Livingston*5*. The infrared spectra*4»5) lend support
to the structures II and III for thiodiacet&tes and
dlthiocarhazates respectively. Even though i t i s too early
to apply transferability of bond energy values for the elu-
cidation ,of structures before studying more M-8 bonds,
the above facts definitely throw enough light on the etruo-
tures of the above compounds.
1. HUM. Jones, B.J.Yow and W.E.Kay, Inorg.Chem*, ^, 166
(1962).
2. J.L.Wood, and M.M.Jones, J.Phy.Ohea., 62, 1049 (1962)
3. V.T.AthavaXe, R.Kalyanaraman and M. Sun dare a an f Ind.J.
Chem., 2t 336 (1969).
4* J.Podlaha and J.Fodlahora, Inorg.Chim.Aota, £, 521 (1970).
5. M.Akbar All, S.E.Livingstone and S.J.Phillips, Inorg.
Chisn.Aota, 5,, 119 (1971).
2.1 (14) A thergodynamia study of trenail;ion metal ion
complexes with 5-Bulfoaallovllo aoldt
(M.Sundaresen, S.P.Awaethi and S.P.Jain*)
5-Sulphosalicylio acid (S3A) is known to complex
•trongly with the transition group metal ions in aqueous
solution. These metal ions have beon known to form two
oomplexes of the type MA and MA2. In the present study,
-70-
an attempt has been made to compute thermodynamlc values,
v i s . , enthalpy change ( AH) and entropy change ( *S) for
the formation of two species in each M-SSA eye tern (where
U ia Ou, Go, Ni, and Mn). Tfc3 etepwise dissociation of 88A
has also been characterised by the respective thermodyna-
mio. constants. The heat changes were measured in a solu-
tion calorimeter with a constant environment. All the
experiments were carried out at 25*0 and an ionic strength
of 0.1 M adjusted with NaClO . After deducting the blanks,
the resultant heat was distributed among the complexes
in the particular solution and A H was calculated,
^ together with £> ?^ values (taken from literature)
gave the respective &> S values.
TABLE 27
Thermodynamio data for sulphosalioyalatecomplexes
Sr.Ro.
Reaction P £>.H A 8Koal/taole Koal/mole e.u.
1. 0u+ 2
2 . OuA"3 . Ni + 2
4 . NiA~5. 0o + 2
6. OoA"r+7 . H1
8 . HA- 2
A-3
v-3
r3
r3
r3
r3
. -3
-4CuA"
CuAfc
NiA*
NiAg 4
OoA"
OoA;4
H 2 A"
-13.3- 9.4- 8.8- 5.2- 8 . 4
- 5 . 0-16.4- 3.4
-2.0-5.9-1.8-3.2-1.3
-3.4-7.1-3.1
+37.9+11.7+23.5+ 6.7+23.8
+ 5.4+31.2+1.1
-71-
• . . n n++
2,1 (15) Thermodynamics of U U2 - PO4 system*
(H.Sundaresan, S.F.Awaathi and O.S.Suryanarayanan*)
When uranyl ion is mixed with phosphoric acid in
*aqueous solution, several new species are formed
thermodynamio functions of these species were evaluated
using a solution calorimeter with constant temperature
environment. Various oonoentrations of U02+ were mixed
with different concentrations of phosphoric acid in pre-
sence of perchloric acid at an ionic strength of 1.0 M
and heat changes due to the formation of new species BIB well
as blank values due to dilution of various reagents involved
were measured. The resultant heat, which i s due to complex
formation only, was distributed among the various species
formed at different phosphoric acid concentrations and
enthalpy change values & B^ were calculated. This,
together with free energy changes b-'F^ was used to compute
entropy ohangeo kS^. Table 28 l i s t s the thermodynamio
data for the formation of three species, i . e . , UOgCH-jPO ) ,
U02(H3P04) (H2P04)+ and U02(H2P04)+. Formation of
U02(H2P04)2 has also been reported^1 *2* but the eonoentra-
tion of the same i s very email under the experimental condi-
tions. Efforts to increase the formation of TJOgCH^11^ r*~
suited in the preoipitation of uranyl ion.
1. C.F.Baee, J.Phy.Chem., 60, 878, (1956).
2. J.M.Sohr«yer and C.P.Baes, J.Am.Chem.Sco., JJs, 354 (1S54).
TABLE 28
Thermodynamic constants foruranyl-phosphate system (25°C)
Reaction ^ 51 &• H & SKcal/mole Kcal/mole e.u,
1.
2.
3.
UO2(H3PO4)""
UO2(H3?O4) (B
OO2(H2PO4) +
: 2PO 4)++.
-1
H* - 1
-0
.04
.81
.99
-3.1
-3.1
-2.0
-6.9
-4.3
-3.4
-73-
2.1 (16) Application of thermogravlmetrlo methods to
DTA ourves t
(P.Y.Hftvindran, T.P.Radh&krishnan and A.K.Sundaram)
Applioation of therm ogravime trio methods for
evaluating the kinetic parameters from DTA ourves hae
been considered. Theoretical DTA ourves were generated
for a known system and the kinetic parameters were evalua-
ted using equations originally derived for thermogravimetrlo
methods taking the fraotion decomposed, «< , as the ratio
of the area, a, swept at time, t , to the total area, A,
under the DTA peak. These equations were also applied to
experimental DTA ourves for sodium bioarbonate.
The decomposition of beneens diasonlum chloride
was chosen for constructing the theoretical DTA ourves
using the fundamental equation of Reed et aP . The
fraotion decomposed, °C, was calculated from the theore-
t ical ourves and the activation energy, Z, was calculated
by the methods of Ooats and Redfern' ' , Horowits and
and Piloyan14^ originally developed for TG
methods*
fhs equation of Coats and nedfefn for * first
order re&otlon takes the form
l08 S - i ^ J „ - J L ^ + oonetsnt
-74-
Th* method of HorowltR and Metsger oan be written ac
log [la A/A-a] - £-£-J U )
whexa <S> • T-T and T~ 1» the temperature at whiob °<
ia 0.632. The energy of aetlvatlon can be calculated by
Piloyan's method for low valueB of << (0--0.5) from
values of E are compared' In Table 29 with thoee repor-
ted by Reed et al* The agreement Is good except for the
method of Horowita and Metzger which is an approximate
The modified TG equations were used for the
luation of the activation energy for sodium bicarbonate
decomposition In static air. The results (Table 30) oom
pare well with the value obtained by the method of
Borchardt and Daniels' '.
1. R.L.Heed, L.Weber and B.S.Gottfried, Ind.Eng.Ghenu,
Fundamentals, £ , 38 (1965).
2. A.W.Coate and J.P.Hodfem, Hature, 201., 68 (1964).
3. H.H.Horowitz and G.Metzger, Anal.Chem., J^t 1464 (1965).
4., O.O.Piloyaa and O.S.Hovlkova, HueB.J.Inorg.Olwm., 23
02, 313 (1967)
5. J.8estakf Talanta, 12, 567 (1966).
6. H.J.Borohardt and F.Daniele, J.Am.Chem.Soo., 21* 41 (1957)
TABLE 29
Activation energies from theoretical DTA curves of benzenediasonium chloride by different thermogravimetric methods
Bun Not
2
4
5
7
8
10
Reed et al(KCal/mole)
32.2
33.8
26.8
30.9
27.2
31.5
Coats and Redfern(KCal/mole)
31.9
32.7
26.7
31.7
27.6
30.7
Piloyan(KCal/mole)
31.1
29.4
25.9
29.3
25.8
28.9
Horowits and Meteeger(KCal/mole)
36.5
36.2
29.3
35.0
28.1
32.8
* She run numbers listed here correspond to those in Heed'sexperimental data
Sampleweight(mgs)
24.9
25.5
25.1
HeatingrateeC/min.
2.5
2.5
2.5
TABLE 30
Act!ration energy from experimentalDTA curves of sodium bicarbonate
Coats and
(KOal/mole)
28.7
29.3
28.5
E, TCr methods
Piloyan Horowitz andMetzger
(KOal/mole) (KCal/mole)
28.5 30.2
29.7 30.5
28.6 29.6
Borchardt andDaniels' DTAmethod
(KCal/mole)
27.5
28.8
26.2
-77-
2,1 (17) A therutogravlmetrlo study of the decomposition
of uranyl oxalate trihydrate:
(P.Y»Ravindran, T.P.Radhakriehnan and A.K.Sundaram)
The dehydration and subsequent decomposition
of uranyl oxalate trihydrate has been studied by thermogra-
vimetry. The primary reaction is the loss of two molecules
of water in. the range of 60-110°C and one molecule of water
in the range of 175-205*0 to give the anhydrous oxalate.
The i n i t i a l dehydration step was studied at two heating
rates of 6* and ?.5°C/min. with the sample weight varying
from 20 to 50 mg. The activation energy was evaluated by
the methods of Goats and Redfern^ ' , Horowitz and Metsger^ '
and also Piloyan et al*5^ (Table 31).
TABIE 31
Activation energies for uranyloxalate trihydrate dehydration
(loss of two moles of water)
SampleWeight(»g)
22.2
30.1
43.6
Heatingrate•C/min.
7.5+1
6.5+0.5
J6 + 0.5
Aotivation energies
Coats and PlloyanBtdfeim
25
26
23
25
25
23
(In ECal/mole)
Horowits *ndMetsger
26
26
24
-78 -
The decomposition of oxalate was studied at
two heating rates of 4° and 6°C/min, The reaction was
markedly dependent on the weight of the sample and heating
rate. The weight loss corresponded to decomposition to
uranium trioxide at heating rates of 6°C/min. for sample
weights below 30 mg. The residue was orange-red in colour
with an 0 (7 ratio of 3.0 + 0.1. When the in i t ia l weight
exceeded 40 mg, the weight loss corresponded to that for
decomposition to uranium dioxide. The decomposition was
Instantaneous and ths residue was 6 r e e l i B t l blaok in oolour.
The final product of decomposition was always U0, for in i -
t ia l sample weights of 10-65 mg at a heating rate of
4°0/min.
The final product of decomposition depends
upon the nature of ambient atmosphere, sample weight and
heating rate. The formation of U0, i s favoured at low
sample weights when there is free accessibility of oxygen
as the sample layer i s thin. At low heating rates, the
movement of the reaction front i s slow and supply of oxygen
by diffusion i s continuous and steady to favour 1J0* forma-
tion even at comparatively large sample weights.
1. A.*.Coats and J.P.Redfern, Nature, 201., 68 (1964).
2. H.H.HorowitB and G.Metsger, Analyt.Chem., 21, 1464 (1963).
3. G.O.Piloyan and O.S.Havlkova, Russ.J.Inorg.Chem., 1,2,
313 (1967),
-79-
2,1 (18) High resolution HMR atudiea of gome nickel (II)
complexes!
(M.H.Dhingra*, B.Maiti and R.M.Sathe)
Mono-1hio derivatives of ji -diketones
such as benzoyl ace-tone (BA), dibensoyl methane (DBM) and
th« theonyl trifluoroacetone (TTA) were prepared by known
methods'' . The nickel complexes of the f3-diketones and
the correspond ing mono-thio analogues (TBA, TDBM,, TTTA)
were prepared by mixing a hot alooholio solution of niokel
aoetate with that of the corresponding llgahd. The compo-
sition and purity of these compounds were determined by
elemental analysis (Table 32) * Further, one mole of the
nickel complex dissolved in chloroform was treated with
two moleB of "V-piooline. The corresponding 1:2 adducts
separated on slow evaporation.
High resolution NMR speotra of the dia™
magnetic parent compounds and their V -picoline adduots
were recorded in CPC15 solution using TMS as the internal
standard. In many cases, i t was not possible to observe
the resonance of the << -proton of the adduot because of
excessive broadening. Speotra of the parent compounds
were therefore also reoorded in V-picoline solution.
The observed isotroplo shifts for
Y -piooline protons ar» given in Table 33. All the pro-
tons have shifted down field, except the V -methyl proton
•Tata Institute of Fundamental Research, Bombay.
-80-
which showed shifts towards high field* the magnitude
of the shift decreasing with increase in the distance of
the particular proton fron the paramagnetic centre. For
pyridine, axially coordinated to the Hi(II) - /^-diketo-
nates, all the proton resonances have been observed to
have shifted downfield*2'. These shifts were interpreted
as being predominantly due to the de&ooali&ation of the
unpaired electron spin from the metal into the 6" orbjfels
of the pyridine moiety. The reversal of the sign of the
shift for the methyl protons of V -picoline revealed in
the present study indies ate a that some -A delocalisation
accompanies the o" delocalisation* To ascertain the
orbltala involved, the fraction of the unpaired spin In
different orbitals of V -piooline have been calculated
from the ratios of the shifts observed for different
protons of V -piooline (Table 32), using a ft spin in
the iV orbitals of the ligend.
Since the octahedral complexes of Ni(II) do not
contain any unpaired electrons in the *2g orbitals (of f^
symmetry), it is likely that the n spin density observed in
the ligand arises out of some indirect mechanism. The un-
paired electrons in the e orbitals of the metal can inter-
aot with the t2g orbitals via spin exchange giving rise to a
residual spin in these orbitals which can then be delocali-
sed over the ligand protons.
1. S.E.livJnfc: tcae, Goord.Chem.Rev., X* 59 (1971).
2. O.N.La Mar, Inorg.Chem., 8, 581, (1969h
Com] ound
Ni{BA)2
Ni(TBA)2
Ni(HBH)2
Ei(T?A)2
?e of
Calcula-ted, £
60.5
55.54
69.85
65.43
38.17
35.9<S
carbon
Observed
61.9
57.01
69.57
63.66
36.54
37.80
TABU5 32
56 of hydrogen
Calcula-t e d , 96
5.05
4.63
4.5
4.19
1*98
1.87
Observed
5.21
4.81
5.01
4.99
1.89
2.20
5* of 1
Calcula-ted, £
16.44
. .
12.47
12.72
23.97
sulphur
Observed*
16.91
• •
12.30
13.17
24.04
+ of
Calcula-ted, £
16.47
15.10
12.20
11.47
11.67
10.97
nickel
Observed*
16,40
14.70
12.1
11.02
11.5
10.66
TABEB 33
The oontact shifts, values of spin density fraction foradduots of V-picoline with aono-thio j3 -^dikstonates.
Compound
• '
Hi(BA)2(V-pio)2
lfi(TBA)g( Y -pic) 2
Hi(DBH)2(V-pic)2
Hi(TDBM)2( Y -p ic ) 2
3ffi(TTA)2 ( Y-pie)g
Hi(TTTA)2(V -p ic) 2
Contact shifts fors —pieoline pro-tons (H«)
-4486
-3540
«•
-3733
. *
-4196
-1574
-1460
-1486
-1222
-1654
-1620
+517
+416
+497
+396
+535
+657
Spin
0.867
, .
0.787
»•
0,530
density fractions
T?
0.127
. .
0,174
• ,
0,386
0.006
. .
0.039
0.083
1CDro
-83-
2,2 ELECTRODE KIHSTICS AHD ELECTROCHEMICAL STUDIES
2«2 (1) A unified theory of chronopotentionwtrio wave as
(X.P.Radhakrlshnan and A.£.Sundaram)
A aimplified general equation has been
derived^ ' for the potential-time curve of a oathodio ohrono-
potentiometrio wave which involves mixed oontrol by di f fu-
sion and charge-transfer. The eleotrode reaction
0 + ne k v E (1)
i e of the f i r s t order and involves e i ther two eoluble
species , 0 and R or the product, R, soluble in mercury.
The i n i t i a l concentration of the oxldant, 0, in the so lu-
t ion i s 0* and no product ie present i n i t i a l l y . I t i s
assumed that mass transfer towards the plane electrode i s
controlled only by diffusion and the influence of double-
layer charging i s n e g l i g i b l e , The effeot of superposed
charge-transfer and diffusion processes on the eleotrode
. k inet ics can be described by the re lat ion
«P [.CMS-VAT]a&T* «P [CMVA]
1 + (jA* exp |nf (E-EB)/fc5f J
where 1 Is the magnitude of the constant current. A, the
electrode area, 1 the measured potential, E B the standard
potential of the system, kg the standard rate oonstant,
c<tfee transfer coefficient, t the time elapsed after th«
beginning of electrolysis, T the transition time end J>0
and Ik are the dlffualon coefficients of th© oxidiaed and
reduced species respectively, This equation is valid when
-84-
th* measured potential is more oathodlo than the standard
potential and this condition is satisfied when — j —
Three limiting cases can be considered*
Reverelble reduction! When the electrode
process is reversible, the contribution of
exp Is
due to the charge-transfer over-voltage is negligible and
#q. 2 beoomeo
where the quarter-wave potential, Br/ii la given by
The standard potential, Eg, can be conveniently replaced
by the formation potential, E£.
Irreversible reduction! When the process is
totally irreversible, the term
I)"]- nP (E-E )«S - exp ^ ?-
Is negligible compared to unity and eq. 2 becomes
-85-
where
Both the transfer coefficient and the standard rate oonstant
con be calculated from a plot of IS vs. log 1 -(~)*
provided the formal or standard potential is known.
Quasi-reversible reduetiont When the electrode
process Is quasi-reversible, the effect of both diffusion
and oharge-transfer over-volt age should be taken into consi-
deration and eq.2 can be rearrange to give
Bm nFAk_O°
(7)
Introducing Et/. and E+ .« and simplifying, we get
where
ezp § (I - B^/4)} (9)
A plot of E vs. log (1-A) should be linear and froa the
slope and intercept, both *C «nd k0 oan be oaloultted* If
the standaurd potential is not known, an apparent rate
-86-
, k1 can b« calculated oaiag the fonfiatl potential,
further, the dependence of B t - 0 on the eatbodic
density can be written as
1 plot of E t l t 0 T8. log *Py* should also be linear and
the kinetic paraaidtera can be calculated.
1. T.P.Badhakriahnan and A.X.Sundaraat ?roo.Ind.Aca<5»8oi.s
t 278 (1972)»
2,2 (2) A study of quasi-reversible chronopotentlometrio
(T.P.Radhakriehnan and A.K.Sundaram)
The evaluation of kinetic parameters for quaei-
reversible chronopoteritiometrlc waves has received very
l i t t l e attention. The method of Anderson and Macero^ '
i s based on a numerical solution of an expression with
three unknown parameters by an Involved iteration proce-
dure. Further, the authors have not substantiated their
method with experimental data for any quasi-reversible
system. In the present study, a simplified expression^
has been used to evaluate the transfer ooeffioient and
standard rate constant of a number of quasi-reversible
systems*
-67-
A sat up for recording the B-t owrves was
aJ»aes)bl*& using a transistorised ecmstant current souroe.
(h*) abrupt r i s s in potential in the in i t ia l portion of the
«-arves i i a baotad off by a lye potentioneter and only the
useful ssgasnt of ths 1-t curve was recorded at high aansl-
on a Honeywell Elaotronio 19 recorder. An iapoored
oell a«t-up wac used with a platinun foil (1 on ) as the
anode. Double distills^ ««r^?ry contained in a perapex
oup of about 2 on diameter, served as ths cathode. The
tip of the Luggin capillary of the calomel reference «]*c-
trode waa kept close to the oathode. Folarographio measure-
aents were ffiade on a manual set-up using a dropping mercury
or dropping amalgam electrode.
She reversible quarter-wave potential, S T/4»
for the reduction of zino ion in sodium sulphate,, ethylene-
diami&e (En), sodium hydroxide and sodium acetate media and
biamuthyl ion in perohlorio acid medium were determined by
recording the composite polarograms with a dropping amalgam
electrode. The concentration of the depolariser in the
solution and amalgam phases were equal and the value of
* vas "fcaktn ae "tne formal potential.
The dependence of *tmQ on oathodio current
density at a o one tan t concentration of the depolariser was
studied for the reduotion of sino in various media. The
-88-
i Et = 0 - Sf!values of << and k^, obtained from a plot of i Et = 0 - Sf!v8e
n^Ag<> t are given in Table 34* The agreement in the
values with those obtained by other methods i s good,
particularly in view of the uncertainty in the direct
recording of E^.^.
Accurate values of Et cQ coJ1 D e obtained by
graphical extrapolation of the plot of E vs log (1-A). The
cbronopotentlometric reduction of t r ivalent europium in
potassium chloride and bismuthyl ion in perchloric acid
medium were studied and the values of oC and k' were
calculated. (Table 34).
1. L.B.Anderson and D.J.Macero: Anal. Chem., J2 , 322 (1965).
2. T. P. Radhakr is hna n and A.K.Sundaramj Proc. Ind. Acad. Sci . ,
2^, 278 (1972).
3. 0.R.Anne Marie Baticle: Acad. Sc i . , Paris,. 254, 668 (1962),
4. R.Sundaresan, S.G.Saraiya and A.K.Sundaram: Proc. Ind.
Acad. Sci. , 66, 120 (1967).
5. H.Matsuda and Y.Ayabe: 2. Elektrochem., Q, 1164 (1959).
6. H.Matauda, Y.Ayabe and K.Adachi: ib id . , 67_, 593 (1963).
7. J.E.B.Randies and K.W.Somerton: Trans. Paraday S o c ,
48, 937 ,(1952).
8. A.A.Moussa and H.M.Saannour: J . Chem. S o c , 2151 (i960).
Metalion
Zn2+4nli
n
n
n
Eu3+4mM
MO*S*
Values of E | ,
Baseelectro-lyte
1M En +0.5H KCl
m KCI +1M NaOH
1M KlfOj +
1M NaOAc
1H KCl
1M HC1OA
CurrentdensitymA/cm
0.1440.750
0.2890.866
0.1440.866
0.1440.866
0.144
0.35
V vs .S.C.E,
0.9801.016
1.396
1.4001.511
1.0111.075
0.623
-0.0246
and log
Slope
0.05
0.10
0.143
0.09
0.103
0.034
Tafcle 34
k' for metal ionsB
V v s .S .C .£»
1.016
1.375
1.420
1.044
0.614
-0.024
Presentstudy
0.63
. 0.29
0.21
0.34
0.58
0.59
in different
<
l itera-turevalue
0.3<"
0.68'*'
o.«<5>
0.37 (6>
-
•
media
-
Presentstudy
2.97
3.63
3.59
3.31
3.52
3.38
log k
Litera-turevalue
3.a<*>
3 .3 ( 5 )
3 . 2 1 ( 6 )
3 .68 ( 7 )
3 .43 ( 8 )
i00
i
-90-
2,2.3 Chronopotentlometric studies in fused ealte-behaviour
of thorium in lithium chloride -potassium chlorideeutectip:
(K.A.Khaagiwale, M.M.Mehta, M.Sundaresan and K.TTnnikrisbnan*)
The set up for chronopotentLometrie studies in
fused salts* ' , T;as further standardised by studying the
reduction of lead chloride in lithium chloride- potassium
chloride eutectic as supporting electrolyte at 45O°C. Constancyi x T *of —^ waa verified over a range of concentrations with
different current densities and electrode areas. Measurements
were done with platinum foil as a. reference electrode, in
contact with 0.1M of Pt(ll) in the eutectio.
Behaviour of thorium ion under the above conditions
was studied with a view to obtain coherent electrodeposition of
thorium metal. Chronopotentlograma were obtained using a three
electrode system consisting of (i) a micro electrode of platinum
wire as an indicator electrode, ( i i ) a large platinum foil
electrode as an auxiliary electrode and ( i i i ) platinum foil in
contact with pt(II) serving as reference electrode. Curves
were obtained for a concentration range of 11.18 x 10~ to
151.19 x 10" moles of ThCl^/ml. The product of * ^ r • was
constant over a tenfold concentration range but decreased with
increasing- concentration. A probable diffusion coefficient
value for thorium ion under the above conditions was calculated
by assuming a single step four electron reduction. The value
of D was found to be 0.1 x 10~* cm2/seo.
• Metallurgy Division, B.A.R.C.
- 0 1 -
Table 35
Values of i T /C for differentoonoentratlona of thorium chloride
Area of working electrode * 0.0421 cm
No.
1*
2.
3.
0ThCH
moles/ml
34.28 x 10"*
60.74 x 10~6
67.86 x 10"*
i
600
60Q
500
TSee
0.72
2.4
3.44
1 *C
15.
15.
13.
1 '
3
6
0
0
0
om
.11
.11
.10
I)/sec.
x 10
x 10~5
x 10~5
1. M.li.Mehta, M.Sundaresan and K.A.Kuaegiwale,BARC Repo*t 639, 81 (1971).
-92-
2.2,4- Voltammetric and chronopotentiometric s tudies ofE u — * Eu^+ reduction at
(R.G.Ehaneshwar and A.V.Kulkarni)
Eu —* Eu^+ reduction at gold ind ica tor e l ec t rode :
Chronopotentiometric s tud ies of Eu reduct ion in
O.Ui ammonium chloride medium have been reported ea r l i e r ^ .
Since the hal ide ions are known t o be adsorbed on the gold
electrode surface to a grea ter extent than the perchlorate ions ,
the study was continued in 0.1M sodium perchlorate medium using
Au/Pt/SCE electrode system in conjunction with Electroaoan 30.
In the voltammetric s tud ies , a p lo t of i /v* against
v*, where i i s peak current and v i s the voltage scan r a t e gave
a s t r a igh t l ine with a negative s lope . This suggests tha t the3+ 2 +
Eu —»• Eu react ion in t h i s medium a l s o i s not revers ib le and
that there i s no chemical reac t ion . The standard r a t e constantKa h f o r t h e e l e c ' f c r o < i e r eac t ion was ca lcula ted using the following
equation for cyclic voltammogram
where ^ l a a function of A- E - the difference in cathodic and
anodio peak po ten t i a l s , r « (D0/DR)*, DQ and Bg being the
diffusion coeff ic ients of the oxidised and reduced form of
the red-ox couple, (the r a t i o i s nearly always unity)and a
- nFV/RT. The KQ h thus calculated i s 6.784 x 10"*4 cm/sec.
-93-
To calculate the kinetic parameters of Su^- » B? +
reaction by chronopctentiometry, i t was necessary to find out
the diffusion coefficient in 0.1M sodium perchlorate. By
plotting iTVA vs C, the concentration of Eu5+, the diffusion
coefficient D was obtained from the slope, by assuming planer
diffusion to be operative. To account for the cylindrical
nature of the electrode, a correction factor R was calculated
by using Dornfield-Evans equation for cylindrical e lect rode^
$ s D* T V ^ , where 0 is the function of R and rd<jHs the
electrode radius. Then from the plot o" i r vA-*R vs 0, the
corrSoted diffusion coefficient of Eu is obtained as
3.286 x 10"" cm/aec. Using usual chronopotentiometric equation
for both direct current and current reversal chronopotentio-
grams, for irreversible reactions (Pig.VI), the average value
-4 /of standard rate constant K . is found to be 3.0 x 10 cin/seo*
The order of the standard rate constant by the cyclic
voltammetry and chronopoterit iometry is the same, but the actual
values differ. The value obtained by the ohronorotentionietric
method i s more accurate, since the cyclic voltammetrio equation
involves some approximations^ *
Further work irj"-lvSs .^termination of rate constants
for other halide ions, in order to understand the process of
adsorption in a quantitative manner.
1. Annual Report, Analytical Chemistry Division, BARO -639 p.68,2. D.I.Dornfield and D.H.Evans, J.Electroonol. Chem., 20(1969)3413. R.G.Dhaneshwar and A.V.Kullterni, Indian J. Ohem., in print.
-94-
2.2.5 Eleetroanalytical study of mercury reduction;
H.Gr.Dhaneshwar and A.V.Kulkarni.
Estimation of mercury in voltammetry presents some
serious problems. The conventional electrode system DME/SCE
cannot be used* Earlier workers have reported mercury(II)
reduction using graphite, zinc or zinc amalgam electrodesv * ,
The present work is carried cut on Electroscan-30, using
Au/Pt/SCE system unless otherwise specified.
Linearly varying potential voltamme'try: The study of mercury(II)
reduction was undertaken for subsequent use in stripping analysis,
employing gold wire indicator electrode. The supporting elec-
trolyte chosen was 0»1M potassium thiocynate aa the mercury
waves were well defined in this medium (Fig.VII). Earlier workers
have reported a single wave for mercury reduction on graphite
electrode in thiooynate mediuur '» On gold electrode, however,2 + 2 +
two waves were obtained corresponding to 2Hg » HgrJ and
Hg2+'—-->2Hl reductions. The" current concentration proportio-
nality was observed for both the curves over a concentration
range of 0.1 to 1.5 mM of Hg(II). The peak potential of the.
first wave varied slightly with concentration, while that of
the second wave varied to a, greater extent, the peak potentials
of the first and the second waves are -0.025 and -1.30V vs. SCE2+at 1.45 mM Hg concentra t ion.
-95-
CycXlo voltammetry: - a cyclic voltammogram of Hg2+ Indicated
that the f i r s t wave 1B neas."''/ reversible, while the eeaond one
seemed to "be i r revers ib le , because in the la t ter caee no anodic
peak was obtained (Pig.VII). AEp i . e . , (Ep) - (Ep) for the
f i r s t wave was 64 mV at higher concentrations and 76 raV at lower
concentrations).
Stripping analysis: Mercury is a very toxic substance and a
hazardous pollutant. The maximum tolerance limit of mercury,
over a short period of time i s 0.05 jug/ml. Estimation of mercury
at suoh low concentrations by conventional voltammetry is d i f f i -
cult and anodic str ipping analysis was therefore employed, wherein
mercury is deposited on to the gold electrode surface end then
stripped back. Although potassium thiocynate was found to be2+particularly good for cathodic reduction of Hg , i t was not
found to be so in stripping analysis, beoause of very high blank
peaks* The blank waves persisted even after purification of the
thiocynate medium by pre-eleotrolyeis for an hour. I t was also
necessary to change the electrode system, in order to eliminate
oompletely any blank curges. The electrode system tried was
Au/Pt/Pt* replacing the calomel reference electrode by platinum.
The supporting electrolyte tried was 10 mM n i t r i c acid of E.Merck,
G.R. puri ty . As Pig.VIII showB, the blank curve was then completely
eliminated. The anodic stripping peak of mercury was obtained
at -0.3V. For the preliminary s tudies , Ilg2* solutions In
-96-
0.115 jx^/vil to 0.4 jug/ml range were pre-electrolyaed for 10 minutes
and anodically Btrlpped after a 30 second reet period. Good
current-concentration linearity was observed over thiB range.
Mercury waa estimated by this technique in tap water.
To one l i t r e of tap water,0.63 ml of concentrated ni t r ic acid was
added and the solution evaporated down to 100 ml. Out of this
solution 2.5 ml were taken and made upto 25 »0 ml. A good anodio
peak of mercury was obtained (curve 4 t Fig.VIH). Meroury oontent
was found to be less than 0.0$ ppm. Further investigation is in
progress.
1. S.P. Perone andW.J. Kretlow, Anal. Ghem., 37., 967(1965)
2. A.V.Kulkarni, M.So. Thesis, "Voltammetric InvestigationsEmploying Various Electrode Systems", Univ. of Bombay, 1969.
2.2.6 Yoltaifimetric. ehronopotentiometrio and ohronoamperqmetriostudies of indium reductions
(R.G.Bhaneshwar and M.M.Palreoha)
The In reduction was studied on Electroscan 30, using
Beckman Hanging Mercury Drop indicator electrode with platinum as
auxiliary electrode and calomel as reference eleotrode. The
study made use of the techniques of voltammetry, oyclio voltam-
metry, chtonopotentiometry and c.hronoamperoraetry, in 0.2M NaCIO,
and 0.2M KNG, media.
Volt ammetryi Voltammograms were recorded at different scan
rates ( v ) , ranging from 10 to 200 mV/sec, * plot of iVv * vs v
is a straight line parallel to the abscissa indicating that the
- 9 7 -
eleofcrode reaction is not preceded or followed by any other
chendcal reaction. Proportionality between the indium peak
current and concentration was found to be satisfactory between
the concentration range 0,8 to 2.0 mM. The peak potential for
In5+ reduction was 0»56V in both the media.
Cyclic Voltammetryt The cyclic voltammograms were also observed
in both the media. For different voltage Bean ra t e s , the diffe-
renoe between the oathodic half peak potential (Ep /g)c and the
anodic half peak potential (E /«) w a 8 found to be 20 mV indi-
cating a reversible three electron reduction.
However, cathodic and anodic peak currents were found
to be unequal, violating- the conditions of perfect reveraibi l i ty .
Surprisingly, the anbdio peak ourrent was much higher than the
cathodic one (fig.IX). In discussing the influence of amalgam
formation on oyclic voltammetry, Beyerbin and Nicholson discussed
the theoretical implications of larger anodic peaks^ ', The
current in Buch cases i s related to the function
x {«A) where V =V D j / % and <t> - (V^D^/r^) xVT, where
a « n¥v/RT, the eymbola having the usual meaning. iFor 4> a °»
both anodic and cathodic currents are equal, but when0.l>#>0.
anodic currents are greater than the cathodio currenta due -t;o1 - •; '• r •.rxl jfiftiiV/c of eloctroA^ rrti6 ar.;''!;.. n form at ion.. Thfe
v ^ l u t ' 3 w e r e c a l c u l a t e d and were f o u n d t o bo l e s a t h w i o . l ,
which explains the much larger anodic currents observed.
-98-
The standard reaction rate constants were not
calculated aince the results obtained regarding the reversi-
bility of the electrode reactions were ambiguous.
Chronopotentlometry; Under different conditions of constant current,
namely, 3.0, 5.0, 10.0 and 15 JA amp, the direct as well as
reverse current chronopotentiometrio technique was used.
Proportionality between i T * and concentration showed
that the reduction is diffusion controlled. The E^/^ for the
forward and ths current reversal ohronopotentiograms are almost
the same, i .e . , -0.555 V ve SOE, indicating that the reduction
is reversible. Clearly, the conditions for reversibility here
are different from thoBe obtained in the cyclic voitammetry.
The diffusion coefficients of In5+ in 0.2M NaOlO and 0.2M KNOj,
determined using Sand's equation are 5.2 x 10" and 4 x 10*"
cm /sec. at 25°C.
Chronoamperometry: Since, the peak potential, E , of the In
reduction is about -0.56V, the chronopotentiograma were
recorded at a fairly negative potential of -0.7V. Proportionality
between i"t* and concentration was satisfactory. The diffusion
coefficients of In5+ in 0.2M each of NaOlO^ and KNO,, calculated
by employing Cottrell 's equation are 5.1 x 10"6 and 5.3 x 10~6
cm /sec respectively. These agree well with those obtained by
ohronopotentiometry.
-99-
The plots of I vs concentration in voltammetry^
vs v* in cyclic voltammetry, I T * VB conoentratton in
ohronopotentiometry and i T * vs concentration in chronoampero-
metry are shown in Fig.X.
1. F.H.Beyerlein and R.S.Nicholson, Anal. Chem., 44 (1972) 16?7.
2.2.7 The effect of laser Irradiation on gold electrode inpotentiometrio titrationB*
(Smt.) M.R.Dhaneshwar, R.Gf.Dhaneshwar and Kum.L.Pandit*)
The effect of infra-red and ultraviolet radiation on
the electrode performance was reported earlier* ' • The work waa
continued with laser i r radiat ion which offers the advantage of being
more specific.AIBOthe energy of radiations can be controlled
effectively.
The input energy of the laser used in the present
Btudy was kept low in the region of 100 to 800 Joules, BO that
melting, vaporisation, emission of different particles are
avoided. The choioe of the type of laser to be employed in the
work was very wide - small and large ruby lasers (6943 A0 of
pulse duration of 40 nano second), helium-neon gas laser which
le.eea continuously (6328 A0) , neodymium doped glass laser
(1.06 u, duration 400 p. sec.) and neodymium doped yttrium-
aluminiuni garnet laser (1»O65 u, duration 10 nano s e e ) . The
mode of laser irradiation was also varied from normal pulses to
a sharp pulse using a Q switch.
* Electronics Division, BARO*
- 1 0 0 -
Thia work concerns with the potentiometric t i t ra t ions
of O.1N NaOH vs. 0.1N HgSO using Au/SCE and Au/Mo system with
laser irradiated gold indicator electrode to study the optimum
conditions neoeseary for the best r e su l t s . The potentials were
measured with a vibron electrometer 33 B-2.
The repults obtained with different laser i r radiat ions
are given in tables 36 and 37. The curves obtained for ruby
laser irradiated Au/Mo system are i l lus t ra ted in Pig.XI. The
increased ourve height i s obtained for almost a l l irradiations*
The increase in the curve height i s related to the t o t a l input
energy of laser as shown in Pig.XII. Steep increase in the
curve height i s obtained when the input energy is inoreased
froffi 500 to 1000 joules. After tha t , the ourve height increases
marginally. The number of shots has no bearing on the resu l t s .
Propt-r focussing of the laser rays on the electrode surface ia
very essent ia l . Helium-neon gas laser was found to be the
least effective. Compared to the energy input in the infra-red
and ul tra-violet i r radia t ions , the energy input in the laser
irradiation is quite small, s t i l l the increases obtained by
.these irradiations are of the same magnitude.
Phot,oohemical surface reaotions involving cupric
oxide films have been studied by ea r l i e r workers ' 2 ' . Ouprio
oxide on copper was thought to undergo the probable photo-
dec oufOBition reaction* 2 C u O - ^ Gu20 + & 02 or CuO-^Cu +|0£.
-101-
While discussing the infra-red irradiation effect on the gold
oxide surface, it was thought that AUgO, is being converted to
AUgOt The present study confirms this supposition.
1. M.R.Dhaneehwar and R.G.Dhaneshwar, Analyst, 97 (1972) 620.
2. N.Hayami, Revs, Phys. Ohem., Japan, 2 (1937) 166.
2.2.8 Standardisation of gold amalgam eleotrode in the strippinganalysis techniquet
(R.G.EhaneBhwar, M.M.Palreeha and L.R.Zarapkar)
The work using gold amalgam indicator electrode for
i
presently
the analysis of lead in the silicate ores has been^ ' reported
The eleotrode used earlier was prepared by dipping
the gold wire in double distilled mercury for a minute and then
washing thoroughly. Sinoe this type of electrode gave irrepro-
duoible results, electrochemical plating of mercury on the gold
wire was tried. Mercury was plated on 1,1 cm long gold wire
electrode by electrodeposition with constant stirring at
-0.4V vs SOE from a 0.01M mercurio nitrate -0.1M potassium
thioeyanate medium for one minute'. Before plating, the electro-
lytic bath waB stripped of its trace impurities by electrolysis
at a mercury cathode. A thin adherent amalgam' fil= was formed
which gave satisfactory response for over three days, the elootrode
response decreases with time, however, necessitatingrecalibration
every day.
-102-
TABLE3A
EFFECT Or RUBY LASER IRRADIATION ON GOLD INDICATOR ELECTRODES
w Electrode Curve End p t , Input Energy Ho. Output' system Height ml. Joulea/ahot of energy Remarks
mV shots raj/shot
1.
2*
3.
4.
5.
b .
7.
Au/Mo
Au/Mo
Au/Mo
Au/Mo
Au/SCB
Au/SCE
Au/SCS
152
193
199
216
155 I
210 j
345
1 7 3 ;
212 !
25.325.3
25.3
25.4
I 19.5iI
19.5
) 19.5
Without irradiation625
800
625
3
3
6
Without irradiation
403.1
403.1
5
5
20
30
20
14
14.4
Peak1!
11
it
S shape
curve
Proper foous-sing. Q awltclaser
ImproperfocussingQ switchedlaser
For 2-4, a email ruby crystal and for 6-7 a large rubycrystal was used.
TABLE
EFFECT OP DIFFERENT LASER IRRADIATION ON GOLD INDICATOR ELECTRODE
No. Au Electrode Laserlength, mm used
Curve Input energy No.ofheight Joules/shot shotsmY
Output energymj/sJiot Remarks
1
2
345678
10
11
12
13
12
12
nn
n
it
n
12
15
163113
" 153137
n 357" 360
" 368
378" 378
165165
135150
Nd?±YAG Laser
75
Nd5i?AG 120
He-Re Gas Laser
155210
Ke-.!e Gas 185
)
I
I)
)
Without
100
200tt
n
441
800
Without
200
Without
Without
170
irradiation
5
510
1510
5irradiation
5
irradiation
irradiation
30 minutes
10
388
10100
8
Double curve
Single curve
n
tt
tt
it
n
it
tt
Double curve
o
V
Single curve,NaOH-H2SO4 both 0.01JTSingle curve
Double curve
30 minutes continuous cw 3-4 mill iwatts Double curve
-104-
The sample or standard solution was deareated for 15
minutes. The pre-electrolysiB was carried out at -0.8V vs SCE,
the oolution toeing stirred by gas bubbling, for 1-10 minutes
depending upon the lead concentration. After 30 seconds rest time,
the potential was scanned towards anodio values at the rate of
40 mV/eeo. Characteristic peak shaped ourrent voltage curves were
obtained. The electrode was subsequently completely stripped
off lead at -0.05V which WBB just sufficient to strip off lead,
but not the mercury film. The same electrode, thus could be used
for a number of experiments.
The work was repeated with the Beokmann Hanging
Mercury Brop Electrode (HIDE). Tha calibration curves obtained
with HMDE and gold amalgam electrodes are shown in Fig.XIII.
Currents per unit electrode area, obtained with the amalgam
electrode are higher than those obtained with HMDE, by almost
fi%*e timeB,
The values obtained with 0.05 jug/ml of Pb showed a
scatter of + 5$ for the amalgam electrode.
Lead was estimated in different samples such as monazite,
zircon, granite, s i l i cate ores and tap water using both HMDE and
gold amalgam wire eleotrodea. The curves in granite are are shown
in Pig.XIV. The residual current for the amalgam electrode i s
higher than that for HMDE. Results of lead estimation in different
samples uBing pDE and amalgam wire eleotrodea are given in
Table 38.
- 105 -
The advantages and disadvantages of HMDE and gold
amalgam wire electrodes in stripping analysis are summed up
in Table 39.
1. Annual Report 1971. BARC Report 639| 1972 p.30.
2.2.9 Study of Catalytic waveB using ffold wire electrode byvoltammetrio techniquet
(R.Gr.Dhaneshvrar and R.B.Vernekar*)
Study was init iated for the usage of gold wire
indicator electrode in voltammetry along with platinum auxiliary
and molybdenum reference eleotrodes on ElectroBoan 30* Cadmium
reduction was studied in different supporting electrolytes.
Table 40 shows different peak currents and potentials obtained in
different media for 1 rail Gd reduction. Obviously the reduction
i s not a straight forward one in the nitrate medium and this la
confirmed by a high negative peak potential in that medium. The
current obtained i s due to the catalytic reduction of M0 . Catalytio
reduction of NO, in presence of 0c>2+ i s observed only with a gold
indicator electrode and not on a dropping mercury electrode. Even
on a gold wire indioator electrode t thin effeot i s observed only
when 0d2+ i s present and not other divalent cation such as Zn ,
Ni2+ , Cu2+ ©to. This abnormal behaviour i s being investigated.
•technical PhyBioe Division, BARO.
-106-
TABIJS 38
ESTIMATION OF USAD BY ANODIC STRIPPING VOLTAMMETRY
No. SampleEleot rode
Gold AmalgamEleotrode Remarks
1 Monazite
2 0-2 , Grani te 29 ppm(colorimetric)
29 ppm 28.7 ppm(average by allmethods)
3
4
5
Zircon
Silicate
Tap water
33 ppm
21.7 ppm
35.5 ppm
21.0 ppm
0.004 ppm (Tolerance level)0.01 ppm
-107-
TABLE 3 9
COMPARISON OP GOLD WIRE AMALGAM ELECTRODE AND HANGING MERCURY
DROP ELECTRODE IN STRIPPING ANALYSIS
No. HMDE GOLD WIRE AMALGAM ELECTRODE
1. Pure Mercury Required
2. Cells of larger volumeused
3. Magnetic stirringessentially used
4* No pretreatmentrequired
5* Small area andtherefore small currents
6. Convenient to use upto10 M concentration
7« Residual ourrents small
8. Drop detachable and nonecessity of bringingback the amalgamatedmetal
9. Interferences by othermetals more likely
10* Ageing has no effect
Only mercury salt required forelectrodeposition of mercury.
Smaller cells can be fabricated.Solution required is less.
Stirring by gas bubblingsatisfactory.
For electroplated gold amalgamelectrode also,no pretreatmentrequired.
Large area and greater thantheoretical currents.
More advantageous for use below—710 M concentrations.
Residual currents large.
For continuous recurring use,it is essential td> dissolve theamalgamated metal after eachexperiment.
Interferences are less likely(Fig.XIV).
Ageing results in diminishingefficiency.
-108-
The current-concentration linearity is not obtained2+for different concentrations of Cd in preaenoe of a fixed
concentration KNO, (0.1M). However, when Cd concentration
is fixed, the current-concentration linearity with varying
nitrate concentration is obtained down to 1.0 mM of NO^.
Experiments are continuing to extend this limit to lower
oonoentrations.2+The effeot of varying Od concentration on the nitrate
catalytic wave ie shown in Table 41* The current deoreases with
decreasing Cd concentration, but not linearly or in a regular
fashion. The peak potential, however does not change much*
Catalytic waves of NO* reduotion were observed on the
dropping mercury electrode in presence of multivalent ions such
as U(VI), Mo(VI), Cr(Vl) and V(Y), but not in presence of bivalent
ions, which are reduced to the metal state. Also on DME, the
current wae proportional to the square root of the concentration
of the nitrate ion, whereas it was directly proportional in the
present case.
The nitrate ion reduction for 0.1M KNO5 and 1.00 mM Cd2 +
was studied in presence of different supporting eleotrolytes. In
presence of 0,1M KC1, 0,1M HaOlO^ and 0.1N HgSO^, the currents
obtained were 6400, 5716 and 8340 uamp respectively. In presenoe
of 0.05ft! each of sulphoaalicylio acid and sodium hydroxide, no
reduotion oould be obtained. Since, there was a four tines
•109-
increase in the catalytic current in presence of 0.1N H SO2 4*
detailed study was undertaken in presence of different acids
such ae 0.1N each of CHjCOOH, HC1 and HCIO^, where the currents
obtained for 1 mM Cd2+ and 0,1N KNO? were 2750, 11000, 6250 uamp
respectively and the peak potentials were -1.02, -0.94, -0.84V.
However, a ourrent-concentration linearity could not be obtained
in presence of any of these acids.
The effect of nitrite ion on the reduction of nitrate
was studied. Nitrite ion itself did not give rise to any catalytio
currents. In presence of nitrite ion (0.1M) for 1 TM Cd2+ and
0.001M KNOj, the catalytic current obtained was 115 ;oamp compared
to 105 juamp obtained in absence of nitrite. Even when the
nitrite ion concentration is changed to 0.0001M, there was no
further change in the nitrate catalytic current,
TABLE 40
PEAK CURRENTS AND POTENTIALS OBTAINED FORCd2+ REDUCTION IN DIFFERENT MEDIA
No. Supporting e l e c t r o l y t e i ^ D
/lamp V v s . Mo
1 C1M KC1 64.6 - 0.76
2 0.1M NaC104 160.0 - 0 . 8 5
3 Acetate buffer 0.115 pH 4.5 no wave
4 0.1M Sulphoualicylic acid no wave
5 0.1M KSO5 4950.0 - 1.38
-110-
EFFECT OF VARYING CADMIUM CONCENTRATIONON THE NITRATE REDUCTION WAVES
No.
12
3456
2+Cd Cone*
DIM
1.00.50.250.10
0.050.01
juamp
4950
453345804116
30751508
f
-1.32-1.28
-1.24-1.21
-1.32-1.24
2.2.10 Voltammetric and cyclic voltammetric studies in aqueousand mixed solvents using gold indicator electrode:
(R.G.Dhaneshwar and R.B.Vernekar*)
Metal wire electrodes offer some advantages over the
conventional dropping mercury electrode in mixed solvent media.
The solution c*oee not creep up the capillary and disturb the
drop time. It has also other disadvantages, such as the pre-
ferential adsorption of some of the solvents and consequent
difficulties ecoountered in cleaning the electrode. In the
light of these considerations, work was undertaken using gold
wire indicator, molybdenum auxiliary and molybdenum reference
electrodes on Electroscan-30.
technical Physics. Division, BARO.
-111-
2 +To begin with, Cd reduction was studed in
different aqueous solutions of methanol. In this medium,
different methods of cleaning the electrode were without any
effeot. The peak currents and potentials obtained for 1.0 ml.l2 +
Cd reduction in 0, 10, 20, 40 and 60$ methanol were 113.4,
72.6, 82.60, 71 and 57 ;aamp and -0.73, -0.73, -0,74,-0.67 and
-0.66 V respectively. The current concentration linearity wao2+obtained from 1,0 mM to 0*1 mM Od concentration in all aqueous
mixtures of methanol. The adsorption of methanol on the electrode
surfaoe is evident from the sharp drop In the peak currents in
different percentages of methanol. Other solvents are being
investigated.
Cyclic voltamraetryj On the dropping mercury electrode, cadmium
reduction is reversible in potassium chloride aB supporting
electrolyte. Its reversibility was tested in KOI and KNO^
media on the gold electrode in aqueous medium as well as in
50$ aqueous mixtures of different organic solvents by employing
the cyolio voltammetric technique. The results are given in
Table 42. For 1.0 mM Cd 2 + reduction in 0.1M KOI,, the anodic
and cathodic currents in aqueous and 60$ methanol were equal,
but the difference between the oathodic and anodic peak poten-
tials were very much greater than 30 mV as required by perfectly
reversible reaction. Thus on gold electrode, Cd + reduction waa
found to be irreversible.
-112-
TABLE 42
CYCLIC VOLTAMMETRIC STUDY OP Cd2* REDUCTION OK
ON GOLD WIRE INDICATOR ELECTRODE
110
1 .2 .
3 .4 .5 .6 .7 .
8 .
9.
10.
11 .12.
13 .14.
15.
Solut ion composition
1.01.0
1.0
0.11.0
0.11.0
0.1
0.1
1.0
mM Cd2 +
mM Cd2 +
mM Cd2
mM Cd2 +
mM Cd2 +
mM Cd2+
mM Cd2 +
mM Cd2+
mM Cd
niM C d 2 +
n
it
it
n
n
+ 0.1M KC1
+ 0.1M KC1 +
+ 0.1M KNOj
+ 0.1M KNO?
+ 0.01M KNOj
+ 0.01M KNO3
+ 0.1M KNO, +0.1M HgSO\
+ 0.1M KNO^ +
0.1N H 2 S0 4
+ 0.01M KNOj +
+ 0.1M KNO, +5O?S methanol
+ 50$ ethanol+ 5036 acetone+ 5O# DMSO+ 5O?6 CH,CN+ 5096 f ormamide •
(E p ) c
V
-0 .66-0,74
-1.30-1.28-1.180-1.04
-1.18
-0.480
no wave
-1 .45
-1.44-1.54-1.21-1.35-0.771-1.4OJ
(sp)a
V
-0.48-0.48
nilnilnilnil
n i l
n i l
n i l
n i ln i ln i ln i lnilnil
jaamp
61.556.5
52504800
445300
8340
8400
3775
33004300
7405250
2375 I900 J
(Vajuamp
61.556.0
nilnilnilnil
n i l
n i l
n i l
n i ln i ln i l
n i lnilnil
-113-
When the reversibility was tested in 0.1 N KNQ,
alone, in presence of 0.1 N H2S0^ and in 50$ aqueous mixtures
of methanol, ethanol, acetone, DMSO, CH,CN and formaznide, it
was observed that in all these cases, only, the oathodic curve
was obtained (Pig.XV) and there ie no trace of any anodic wave*
In view of the fact that the catalytic reduction of nitrate
ie Involved in theiie processes, this is understandable since
only the forward reaction is very predominant. Variations in
the concentration of cadmium or nitrate does not change the
situation.
The least current was obtained in the case of DMSO,
which seems to retard the oatalytio process. Only in aceto-
nitrile, the current obtained was comparable to that in the
aqueous solution, while in the case of other solvents, the
currents were lower than those in water, This was obviously
due to adsorption which also shifted the potentials towards
more negative values (Table 42). Exoept in DMSO, the catalytic
reduction of NO* was not hampered to any appreciable extent
by the organic solvents.
The nitrate ion - current linearity,was tested in
presence of 1o00 mM Gd and different percentages of forma-
mide and was found to extend upto 0*1 mM NO* concentration*
No linearity however could be obtained in acetone. Further
study in other solvents is-In progress.
-114 -
2.?,11 Chronopotentiometric study of eome ions.in different
^ end non-oomplexing supporting eleotrolytes:
(K.A.Khasgiwale, S.V.Iyer* and M.Sundareean)
The teohnique of ohronopotentiometry was used to
study the reductions of cobalt, nickel, and sine ions to ascer-
tain the effect of supporting electrolytes like pyridine and
substituted pyridine compounds on the degree of irreverslfoility.
Chronopotentiograms were obtained with (1) mercury pool as an
indicator electrode ( i i ) platinum wire spiral ae auxilliary
electrode and ( i l l ) 3.C.E, as the referenoe electrode.
Curves were obtained with varying concentration of
these ions under different current density conditions/ After
fcs-oertainirtg the process to be a diffusion controlled,
curves were obtained in different supporting electrolytes
(i) KC1, ( i i ) KOI with varying concentrations of pyridine,
( i l l ) pyridine phosphate buffer (iv) substituted pyridine
oompounds + phosphate buffer. Values of diffusion coeffiolente,
C£YL<L'S w e r e calculated which showed a tendency towards
reversibility in pyridine phosphate buffer,
• Metallurgy Division, BARO.
2.2,12 Electrolyte solutions
(P«S•Ramanathan)
The hypernetted-ohain integral equation-approximation
method is used to calculate the ion-Ion pair correlation
- 1 1 5 -
f unctions and the thermadynamlc properties of models based on
an ion-ion pair potential having 4 terms: the usual coulomb
terra, a core repulsion terra, a term to represent a well-known
dielectr ic repulsion effect and a"GurneyM term to represent
the effect of the overlap of the structure modified regions,
eolvation shells or coepheres, when the ions come close together•
The coefficient AiJ of the las t term for each pair i , 3 oi ionio
epeoiea i s the only parameter that i s adjusted to f i t the solu-
tion data* I t Is determined by f i t t i ng excess free energy
(osmotio coefficient) data. I t i s soaled to represent the molar
free energy change of water displaced from the cospheres when
they overlap. The corresponding entropy change S. . and volume
ohange V ^ are determined by f i t t i ng , respectively excess
enthalpy and excess volume data. A consistent set of these
parameters, which represents rnuoh of what 1B known about the
thermodynamic excess functions of solutions of t e t ra alkyl-
ammonlum halides at concentrations upto 0.5M is interpreted
as far as possible in terras of the data for therniOdynamlo
solvation functions for the seme systems*
P.S.&amanathan, O.V.Kriahnan and H.L.Friedman, Journal ofSolution Chemistry, J., 237 (1972).
~1 1 6 -
2.3
2.3.1 Hair analysis(S.Ganpadharan, (KUDI.) V.V.Lakalnni and M.Sankar Das)
Investigation to establish the experimental errors,
the effects of washing procedures and in-person variation were
completed and sectional analyses were carried out in detail with
a. view to observe correlations between the growth of hair and
the trace element profile. Scalp hair samples 50-100 cm in
length representing a time span of ~ 5-10 years were collected
by combing, from ladies with known case histories, particularly
in regard to dietary habits, health and profession. The hair
samples in their non-anagen phase, differentiated by their roots,
were analysed in 10 cm sections by irradiating at CIRUS followed
by measurements with Ge(Li) end Na'l(Tl) detectors. The concen-
trations of the following elements have been determined: sodium,
chlorine, manganese, cobalt, copper, zinc, arsenic, selenium,
silver, iodine, gold and mercury. Absolute concentration have
been determined for most of the elements. Due to unusually
large values for the concentration of mercury and the reported
difficulties in the containment of meroury during irradiation,
some samples were irradiated at Apsara having different tempera-
ture and flux conditions, and mercury was radiochemically isolated,
She results were in agreement with the earlier values. Pig.XVI
shows the results for one of the samples. The values for Se and
Hg are in broad agreement with the known case histories. Although
-117-
several elements did not reveal large fluctuations, an examina-
tion of the time-dependent variation seems to pose serious
I'foblemsin application to forensic science^ '.
In order-to get standards, comparable in geometry with
hair samples during irradiation and counting, nylone strandB
were analysed for the trace element contents. Sodium, chlorine,
manganese, copper .and gold have beexi detected in the concentra-
tion range of 0.05-10 ppm.
2.3.2 Firearm discharge reaidues:
(S.Gangadharan, G.R.Relan*, Tej Singh* and M.Sankar Das)
In order to investigate the feasibility of identifying
a bullet hole, estimating the range of firing and identifying the
shooter through the trace elements in the residues of bullet/
cartridge primer, several samples obtained by firing different
types of cartridges (after removing: the bullet and powder) have
been analysed. The test-fired cloth samples, provided by CFSL,
Calcutta, were irradiated and the product nuclides of interest
were separated. The radiochemical prooedure has been developed to
separate copper, antimony, barium and mercury.
In addition to the primer residue of cartridges, bullets
of various types, provided by CPSL, Calcutta, are to be analysed
for their trace element contents prior to coding with known
elements.
(1) Paper submitted to the second international conference onforensic activation analysis held at Glasgow, Scotland,September 1972.
* Central Forensic Science Laboratory, Calcutta.
-118-
2.4 ION EXCHANGE STUDIES:
2,4.1 Thermodynamics of So*+ - H* oatlon exchanges
(Smt. Chinnama*", M. Sundaresan and B.ti. Jangida).
In the present work three differently crosslinked,
4, 8 and 1296 (DVB) polystyrenesulfonic aoid type (Dowex 50W)
resins were used to obtain thermodynamic data for the exchange
of eoandium ( I I I ) with hydrogen, ions. The batch equilibrium
method was used to find out the ionic equilibrium distr ibut ion
coefficient, Kffl using * So as tracer at a to ta l normality of
0,15 at 25*0. These K values were corrected for the act iv i ty
coefficients of the mixed electrolyte of scandium chloride and' 1 )hydrochloric acid solutions using the equation of Guggenheim^
and Scatohard* ^ and the Broneted principle of specific in te r -
actions to give Ka Values. Thermodynamic equilibrium.constant,
K i s being determined from the relation
1 1In K = f in Ka dxe 3+ - \ (a+bxQ3+ + cx^5+) dxa 3f
where XgQ3+ i s t h e equivalent fraction of scandium ions in the
resin. The integration within the l imits i s being calculated
making use of the above polynomial with the help of CDC 3600
computer'.
The integrated \alues will provide the thermodynanic equi-
librium constants which, in turn, wil l give the standard free energy
ohange for the cation exchange system.1. Guggenheim E., Phil . Mag., 19, 588 (1935)2. Scatchard G. Chem. Rev., 19 (1936), 309* D and E.E. Division, BARC.
- 1 1 9 -
2«4.2 Use of hydrated antimony pent oxide as a selective Ionretention medium:
(H.K.Iyer end K.R.Krishnarooorthy)
Hydrated antimony pentoxide (HAF) hae been uaed as
a selective sorbent to remove sodium activity in radiochemlcal
separations. This enables the detection and measurement of
nuelidea having half l ives between 5 hours and 5 daya, par t i -
cularly in the activation analysis of biological samples.
The HAP used in our study was prepared by the hydrolysis
of a solution of antimony metal in a mixture of hydrochloric and
ni t r ic acids . The precipitate of HAP was centrifuged, washed
and dried a t 300°C tp yield a produot which gave reproducible
resu l t s . I t s oapacity for sodium was 0,7 meq/g09 A
Decontamination with respect to Na was studied by
equilibration experiments. By two equilibrations of 25 ml of a
solution (containing 1 mg of iodium labelled with 24Na and traces
of other ione with 40 pg of carrier for each element) with 0.2!i g
of HAP, it was observed that better than 99-5$ of Bodium could be
removed. The reooveriee of Cu(II), Co(Il), Or(JII), Au(III),
la(III) and Sc(III) were evaluated. Exoept for So and La all
other ions showed recoveries of 90-10096. This procedure is being
applied to the analysis of biological samples.
- 1 2 0 -
~.4.5 Ion exchange resins as standards for activation analysis*
(S.K.Kayaeth and R.K.Iyer)
Both oation and anion exchange resins can be used as
convenient media for holding known amounts of metallic ions.
These can thus serve as standards in activation analysis since
the resins themselves do not get activated to any significant
extent. Over conventional standards in solution, the resin
standards have many advantages t they can be readily prepared
for an irradiation, have longer shelf life and are not subject
to hydrolysis or loss by adsorption on the walls of the container.
A programme of preparing resins containing various
metallic ions on ion-exchange resins has been undertaken.
Dowex 50Yf x 8 (50-100 mesh) resin containing ^ 100 ug/g of
manganese, sodium or copper were prepared and the suitability of
these resins with respeot to uniformity and long term stability
over a period of months is being evaluated. Furthermore* i t
la also shown that such resins can be used for analysis involving
Tidiochemical separations, by suitably eluting the activity from
tho resin. Resins containing Hg, Au and Sb are being evaluated,
cjinoe, for these elements, solution standards have definite
araw backs.
- 1 2 1 -
2.4«4. Use of a weak oation exchanger in the recovery ofzinc and, niokelt
(Ch.S.Lakebmi)
With a view to effeot recoveries of aino from effluentB
of the rayon industry, exchange of zino on Beokarb 226 was studied
under different experimental conditions. The exchange was found
to be maximum at a pH of 7*0. The adsorbed zinc could be reoo-
vered by elutlon with any "mineral acid.
Similarly, maximum exchange of nickel from sulphate
solutions occurred in the pH range 7*0 - 9*0* Formic acid was
found to be a satisfactory eluting agent,
2 .5 GAS OHROYLATQGRAPHY
P.5*1 At tapu lg i t e in /gas ohromatographyt
(V.S.Sarang, P.S.Ramanathan and Gh.Venkateswarlu)
At tapulg i t e was examined as an adsorbent using 0 2 , Ng ,
Ar, 00 2 and OgHg as sample gases and He, Hg, Kg, Og and Ar au
carrier gases (o .gh • The studies revealed that good separation
could be aohleved between 02Alg/Ar and G02/02H2. However, the
unusually long tailing exhibited by C0£ hindered & olean separation
between 00g and OgHg. An interee^ing observation was that C02
(with Ar aa e.g.') and 0gH2 (with 02 and Ng as e.g.) gave T.O.
deteotor responses in a direction opposite to that expeoted from
the values of their thermal conductivities. Besides, a small
reverse peak wee found to ocour prior to the major C02 peak when
02 and H2 were used as o.g»
-122-
2.5.2 Zeolites of Indian origin aa adsorbents in gas chromatographv:
(A.G.Datar, P.S.Ramanathan and M.Sankar Das)
Kaollnite and bentonite (montmorlllonite) were
evaluated as adsorbents using Og, Ng, Ar, GOgt NgO, CgHg and HgS
as sample gases and He, Ar, Og and Ng as carrier gases. 30-50 mesh
Kaollnite packed in a polythene column (81 x i") was found to
separate Og/Nr/Ar, COg/NgO, CgHg and HgS at room temperature
irrespective of the e g , employed. In the oase of bentonitet
COg, NgO and CgHg exhibited long tailings thus hindering a
complete separation of these components. HgS was quantitatively
retained by this column. 30-50 mesh montmorillonite packed in
y x i" ooluian wao found to separate ( i ) OgAg/Ar and COg/NgO
and ( i i ) Og/Ng/Ar and CgHg "thou€n a satisfactory separation
between COg/NgO and OgHg could not be achieved. Interestingly,
COg and NgO exhibit similar characteristics on each adsorbent.
Anomalous T.C, detector responses similar to those
described with attapulgite were found for ( i ) COg, HgO (with
Kaolinite as stationary phase and Ar as o.g.) ( i i ) COg and NgO
(with bentonite as stationary phase and Ar as e.g. and
( i l l ) OgHg (with Og and N2 as e.g. for both stationary phases),
2.5.3 &as chromatQgraphic studies with modified forms of s i l i ca gel;
(A.G.Datar, P.S.Ramanathan and M.Sankar Das)
6.C. studies were also carried out using pure and
modified forma of s i l i ca gel as stationary phases, Chromatographio
grade s i l i ca gel and i t s modified form (loaded with different
-123-
amountB of copper and cobalt ammonia complexes) were subjected to
thermal analyses and their surface area determined. The thermal
s tab i l i t y of the-complexes increased by loading on s i l i c a ge l ,
indicating olearly so l id - so l id interactions. Studies with 0 2 , Np,
C02 and 02H2 as sample gases and Ar as e .g . revealed that the
retention charaoterietics get considerably altered by the loading
on the s i l i c a g e l . I t could be inferred that the loaded complex
does not merely block the act ive s i t e s but plays a aef lnite role
in modifying the retention characterist ics fcy interacting with
s i l i c a gel as wel l . The s i l i c a gel loaded with cupra ammonium
complex retained HgS quantitatively. This could be seen by the
blackening of the blue coloured modified s i l i c a ge l . This behaviour
i s being studied for possible applications in air pollution studies.
3 . FABRICATION AND SETTING UP OF EQUIPMENTS
3.1 Solid Source Mass Spectrometer:
(T.R.Mahalingam, P.Murugaiyan, K.S.Sonni and Ch.Venkateswarlu)
The commissioning of the double fooussing solid-
source mass spectrometer Nuclide GRAF-3S was an important event
during the current year. The acquisition of this equipment has
considerably augmented the analytical f a c i l i t i e s in the Division.
The schematic diagram of the MS i s given in Pig.XVII.
A system of d i f ferent ia l pumping achieves the necessary highg ' 7
degree of evacuation, 10 to 10"' torr in the source region,
less than 10"8 torr in tiae analyser region and 2-5 * 10 torr
in the detector.region.
-124-
The samples themselves serve as electrodes and are2
cut ia the form of rods of 2 cm length and 0.03-0.05 cm cross
section. These are chemically cleaned and pre-sparked in the
spectrometer to remove surface contamination. For each sample,
15 exposures in steps of \/10 are recorded. A rapid semi-
quantitative estimation can toe made by visually finding the
exposures at which the matrix and the Impurity lines become just
detectable. For a quantitative measurement, the plate has to be
scanned with a deneitometer and the impurity concentration
determined by comparing the exposures of matrix and impurity
that produce the same optical density (0,20). The instrument is
particularly useful for rapid scanning of elemental profiles and
trace analysis (at ppb levels) of reactor and semi-conductor
materials.
Because of some equipment failures, the two engineers
from Kuclide Corporation, returned be-fore the desired vacuum of-82-4 x 10 torr could.be established and the equipment fully
commissioned. The desired vacuum, however, was successfully
realised after repeated baking and a prolonged •search1 and
subsequent closure of a leak of the order of 6 x 10 torr/sec
on the magnet pole face.
Typical results for the semi-quantitative estimation
of impurities in sil icon samples received from the chemical
Engineering Division, are given in Table 43.
-125-
TABLE 43
Impurities in Silicon
Sample
Impurities
1 • Carbon
2 . Oxygen
3 . Aluminium
4 . Phosphorus
5- Chlorine-35
6. Arsenic
7 . Antimony.
8 . Tantalum
(A)
Wt.ppm
429.0
5900.0
0.038
<0.05
* 12.5
<:o.i
<0.3
<0.5
(B)
Wt.ppm
690
(C)
Wt.ppm
2
180 (inho- 180 (inho-mogeneoua) mogeneous)
0.4
< 0.05
630.0
<0.1
<0.3
<0.5
0.1
0 .4
23
<0.1
40.3
<0.5
(Wafer)
Wt«ppm
1
17000 ( in -homogeneous
10
<0,05
0.5
4 0.1
<0.3
<0.5
- This versatile equipment is capable of analysing
impurities in a wide variety of samples like metals, alloys,
ceramios, pigments, minerals, biological materials, oorrosion
residues and air pollutants.
3.2 Oarbon. analysis fry Eeoo WR-12 analyser:
(S.N.Hevankar and C.S.P.Iyer)
With the increasing activities connected with the
construction of power reactftrs, the need for analysis of
structural materials to specification has considerably gone up.
-126-
To meet the present and future demands in thla respect, a
Leco WR-1? carbon analyser hae been acquired and conuniaaioned.
She analyser employe the oombustion method and enables
a rapid estimation (about 2 minutes per sample) of the carbon
content in atruotural materials like s tee ls , nuclear materials
such as airconium or uranium and miscellaneous samples like
slags and rubber*
The sample is burnt in a current of oxygen in an
induction furnace, all the carbon is converted to COg and
adsorbed on a chrcroatographio column and i s finally measured
with a thermal conductivity ce l l . (Fig.XVIII).
An evaluation of the results have shown that the
results read out on a digital voltmeter are accurate to
»002# in the range 0.02 - O.2O7& carbon.
3.3 Pyrohydrolytic determination of fluoride on ziroaloy surfacei
(M.M./.li)
An apparatus baaed on the work of Stewart et al* '
was assembled for the pyrohydrolytlo determination of fluoride on
siroaloy surfaoe.
Fluoride present on asircaloy samples was pyrohydrolysed
at 900°-1000°C by passing air saturated with steam over the alloy,
kept in a quartz tube. Hydrofluosilioic aoid produced was
absorbed in 10 ml of 0.1N sodium hydroxide solution. 100 ml of
(1)R.B.Stewart, S.Elohuk, and M.A.Grant, AECL-2799* November 196?.
-127-
dieti l late was collected. 9*0 ml of 0.1N perchloric aoia
va-ied to the d i s t i l la te . The volume was reduced and
up to 50 ml in a volumetric flask. *
25 ml of the solution was taken and fluoride
,* the standard spectrophotometrie procedure involving the
it rolling of the colour of alurainium-chrome-Azurol-S.complex*
As low as 2 ug of fluoride could be estimated by thin
'.'•.4 Continuous flow apparatus for surface area measurement ofpowders:
(H.K.Bhat and T.S.Krishnamoorthy)
Surface area of powders is generally measured by the
rue ,- od of Brunauer, Emmett and Teller (BEX method). Adsorption
vJ: nitrogen gas by the sample at liquid nitrogen temperature is
measured at various equilibrium pressures in a conventional
volumetric apparatus or to a lesser extent in a gravimetric
r.rparatus, both involving a high vacuum set up. Prom the
adsorption data so obtained, the surface area i s calculated
by the use of BET equation.
A continuous flow" apparatus has now been set up,(1)r>rasea on the earlier work started by Nelsen and Eggertsen*
Here the use of a conventional vacuum apparatus ia dispensed
with. The adsorption of nitrogen by the sample at liquid
(1) E.M.Neleon and B.T.Eggertsen, Anal.Chem.^, 1387 (1958)
•128-
nltrogen temperature, takes place from a continuously flowing
stream of a mixture of hydrogen and nitrogen. The gas flows
through the two arms of a thermal oonduotivity oell before
and after adsorption/desorption. The change in response of
the thermal conductivity oell due to adsorptlon/desorption 1B
recorded and the area under the curves is taken as Indicative
of the amount of gaa adsorbed/deaorbed. The experiment can be
repeated at different partial flow rates of nitrogen and the
data obtained can be used to calculate the surface area of the
powder by the conventional BET equation*
3.5» Preparation of electrodeless discharge tubes for atomicabsorption and fluorescence work:
(P.Murugaiyan and S.Natarajan)
Bismuth, magnesium and sodium tubes were prepared
essentially following the procedure described by West et al* '.
These have been found to give highly intense and stable spectral
light output. These are suitable for atomic absorption studies
and the sensitivities observed are oompared to those reported
for Techtron hollow .cathode lamps. The magnesium tube has not
shown any deterioration in performance even after 100 hours of
operation, contrary to the experience of others'.2'.
1. T.S.West, Talanta, ii, 551 (1967).
2. K.M.Aldous, B.M.Dagnall and T.S.West, Anal. Ohlm. Aota,t +57 (1969).
•129-
TABLE 44-
Comparison of sensitivities of electrodeless discharge tubei3prepared in the laboratory and commercially available hollow
cathode lamps
Sensitivities for 1$ absorption inElement
EDT
Bi 0.4 0,24
Mg 0.03 0.004
Na 0.03 0.004
3.6 A power supply for hollow cathode lamps used for atomic
absorption;
(S.N.Barve, N.S.Kapre and SoNatarajan).
This unit supplies power to energise the hollow cathode
lamps used ae spectral sources in atomic absorption and f luoreaoence
studies. The unit is a constant current source where the current
can be adjusted from 5 to 70 ma in ten steps. The striking voltage
can be increased upto 700 volte. Meters have been provided to read
the output current and voltage.
The unit works on 230V A.C. and needs no imported com-
ponent. Along with the hollow cathode lamps fabricated by the
(3) Hollow cathode lamp Data, Varlan Techtron - 1970.
- 130-
Electronica Division, the light source becomes a complete
indeglnous product. The operating condition for the cathode
lamps for Fe, Cu, Hi, Pb etc. along with this regulated power
supply were studied, with a Techtron AA-4 speetrophotometer
using a meohanical chopper for modulation. The sensitivities
are comparable to those of the commercially available hollow
cathode lamps (Table 45) • The set up is being regularly used
for atomic absorption work in the Division.
Element
Cu
Ni
Pb
Fe
Co
3.
3247.5#
23200 J2
2170.0fl
2483.3£
2407.38
CurrentI d . A .
10
20
.10
25
20
7 Beckman-DU-Power
TABLE
Slit•microns.
50
50.
300
50
25
supplys
45
Sensitivitiesus/ml for 1# absorptionHCL made byElectronics
0.06
0,11
• 0.3
0.12
0.1
CommercialDn. HOL
0
0
0
0
0
.04
.07
.12
.07
.07
(S.N.Barve, J.C.Dagli and N.S.Kapre)
Discharging of dry batteries used for power supplies
is a common trouble with Beokman-DU-spectrophotometer. The
batteries required are also non-standard type and are not
- 1 3 1 -
readily available in the market. To overcome this diffioulty,
a small power eupjly unit has been built to replace a l l the
batteries in the power supply. The unit needs no imported
components and is completely indigenous.
The unit contains following supplies.*
22.5V plate supply for Ilnd Amp. tube
15V p l a t e supply fo r 1 s t Amp. tube
15V variable screen supply
15V red photo tube supply
6V tungs t en lamp supply
560V blie photomultiplier power supply
+4-Q--2 Biasing and filament power supply.
The power supply output is regulated against mains
variations, loa^ variations and temperature variations and is so
stable that the dark current does not vary for days together.
Five such units are in operation in the Division and one each has
Toeen supplied to Reactor Operations Division and St.Xaviers
College, Bombay.
3.8 Sweep supply unit for Anodic stripping voltammetry,
(K.S.Kapre)
Anodic stripping voltammetry using a stationary
microelectrode, for example,a hanging mercury drop electrode,
faeilitiatesdeterminationa of very small amounts (of the order
of 10"8M or lower) of electro-active substances. An essential
-132-
requirement for this technique is a voltage scanning device.
One unit using an operational amplifier has been built for
this purpose.
I t has a sweep span of 0-2 volts and provision has
been made to provide a cathodic or anodic sweep. The sweep
rate i s adjustable between 200 raV per min. to 1 volt per minute.
The starting, potential of the sweep can be fixed at any desired
value. The sweep can also be terminated at any required poten-
t ial value. The next sweep can be made to start either from
this value or from zero with the help of a resetting switch.
The potential drift is kept at a minimum and can be controlled.
The unit works on 230 volts from the mains.
3 9 Conductivity bridge;
(J.C.Dagli)
A compaot transistorised conductance bridge - Jones
and Josephs type"' has been built for use of the Chemistry
trainees in B.juR.C* The circuit diagram of the 220V line
operated unit i s given in Pig.XIX and includes a bui l t - in 1 Kc/s.
sine' wave generator, amplifier - rectif ier unit and panel meter
for direct observation of the null point when the bridge i s
balanced. Provision has been made for standardising the ratio
arms of the bridge with a d.c. source. . In addition, Wagner
grounding and oell-oapacitance compensation fac i l i t i e s have also
(i) G.Jones and R.C.Josephs, J.Amer.Gliem.Soc, £0, 1049 (1928).
-133-
been incorporated. In this unit, spurious capaoitive and
inductive reaotances are reduced to a minimum so that a sharp
null balance can be attained during conductance measurement.
The unit i s completely indigenous and can be made available
to outside institutions.
3.10 Manual polarographt
(J.C.Dagll).
A simple manual polarograph was fabricated for the
use of chemistry trainees of the B.A.B.C. Training School.
The circuit consists of (1) Ten turn potentiometers
providing potential,0-1 V and 0.0-0.1 ^(2) A variable resistance
for standardisation against a Western-Cadmium cell>and (3) A
variable shunt setting for varying galvanometer sensitivity.
Used in conjunction with an external spot galvonometer, etandared
oell and the dropping mercury electrode, this simple and locally
fabricated set up wi l l be ideal for atudentB making their first
acquaintance with the technique of polarography.
-134-
3.11 Chart area Integrator:
(S.N.Barve)
An area integrator was built to measure areas under
the peaks produced by a thermal conductivity deteotor on a
chart paper. This has obviated the time-consuming area
measurements by a planimeter. The peaks and their areas are
recorded simultaneously as two separate ourves. The first
ourve indioates the off balance voltage in the bridge as a
function of time while the other ourve gives the area under
the peaks U « C 2 V dt.}.
-135-
AFPEHDIX I
During the current year 2010 samples were received fory of which 1939 samples, involving 5725 determinations, were
analysed. A breakup of the work in respect of the various divisionsof the B.A.R.C. and other ins t i tu t ions i s given below.
DIVISIONAL BREAK UP OF SERVICE ANALYSIS FOR THE YE/E 1972
3.No. Source No. of No of deter-samples minations.
'! Atomic Fuels Division! 500 1547
iMetallurgy Division*
a) Physical Metallurgy Section.b) Ceramics Section(c) C orrosi on and Electro-
metallurgy section.Extractive Metallurgy SectionOre Dressing section
5 Chemical Engineering Divisions
(a) Uranium Metal Plant(b) Ore Extraction Section(c) Zirconium Oxide Section
4 Heavy Water and Stable IsotopeProduction Division
5 Chemistry Division
6 Health Physios Division
7 Isotope Division
8 Reactor Engineering Division
9 Reactor Operation Division
10 Desalination & Effluent EngineeringDivision
11 Technical Physios Division
12 Electronics Division
13 Nuclear Physics Division
4813
7013038
32748
15
135
34
5
32
78
6
1
3
6
7044
11225463
954616
92
583
64
9
101
260
45
2
8
32
- 1 3 6 -
S.No. Source No. of No. ofsamples Determinations
54 Director, Physios Group
15 Variable Energy Cyclotron Project
16 Architectural ft Civil EngineeringDivision
17 Central Workshop
18 Fuel Reprocessing Division
Department of Atomlo Energy
19 Directorate of Radiation Protection
20 Atomic Minerals Division
21 Indian P.are Earths Ltd.
22 Tata Institute of FundamentalResearch
23 Power Project Engineering Division
24 Rajasthan Atomic Power Project
25 Tarapore Atomic Power Project
26 Reactor Research Centre, Kalpakkaa,
27 Nuclear Fuel Complex, Hyderabad
28 Uranium Corporation of India
Universities and other Institutions
29 Defence Scienoe Laboratory,Ministry of Defence 4 4
30 Hindustan Lever 2 4
5
15
3
62
11
4
81
29
86
132
7
1
38
5
31
5
47
12
173
44
11
208
90
215
319
28
4
106
5
124
-137-
S.NOc
31
32
33
34
35
36
37
38
39
40
41
4 2 ,
43
44
Source
Hindustan Steele Ltd.
Phargandhara Chemical Works
NOCIL
lareen Toubro
Shipping Corporation of India
Royal Minerals & Metals
I . I . T . , Kanpur
Indian Dystuff Industries
Shree M.N.Ranade
Shree Kanji Anandji
Central Scientifio InstrumentsOrganisation, Chandigarh.
Andhra University, V/altair.
D & H Secheron Electrodes Pvt.Ltd.
Fer t i l i ze r Corporation of India
No. ofsamples
6
3
8
1
8
1
1
5
4
1
1
16
4
13
No. of Deter-minations.
19
29
39
2
19
2
2
14
20
7
8
64
16
13
APPENDIX II
a ID e Institution Field of training
1. Shri B.Satyacarayana2* Dr B.Ganapathy Sundaram.3. Shri C.S.Doshi
4. Shri B.H.Patel5» Dr V.S.Bhagwat
6« Dr L.P.Pandey
7. Shri K.Guha
8* Shri A.V.Krishnan
9. Shri S.K.Ghosh
1JO« Dr S.K.Bhargava11. Shri Si-raramakriahnan )12. Kum.Shanta Chatterjee )13. Shri A.Tas )
14-* Dr R.T.Sane.
Andhra University, Waltair.Vivekananda College, Kadrae.Hajasthan ground WaterBoard, Ha|asthan.University of MaxethwadaParle College
National Metallurgical Lab.,Jamsbedpur.Centre of Advanced Study inGeology, University of Sagar,Madhya Pradesh.
Space Science TechnologyCentre, Trivandrta.
Geological Stixvey of India,Calcutta. \ '
University of Rajasthan
St.Xavier's College, Bombay.
Chem. Dept. Ramnerain RuiaCollege, Bombay.
Activation Analysis.Use of Tracers in Analytical Chemistry.Training in handling of sophisticatedElectronics Instruments.Thermocnedcal measurements.Conduc tome try, spectrophotometry andpotentiesetry.
Instrtmental Analysis
Activation Analysis
Folarogra phic & Allied Techniaues.
Activation Analysis.
YoltamsetryPolarography U.V.spectrometry, carbon-hydrogen micro analysis andchromatography.
Polarography and spectrophotometry.
-139-
APPENDIX III
Title of the paper Author(s) Journal
1. Some mixed complexes oflanthanide ions.
2* The effect of infra-redand ultraviolet irradiationon &old indicator eleotrodein voltammetry.
3. Kinetic parameters fromohronopotentiometriowaves.
4. Polarography of indiumin lactate medium.
5* Solvent extraction studiesof indium-lactate complexes,
6. The effect of infra-redirradiation on the poten-tiometric behaviour ofgold wire electrodes.
7. The ion exchange behaviourof beryllium ammoniumphosphate towards Bodiumand potassium ions insolution.
8* Simultaneous extractionand spectrophbtometriodetermination of titaniumwith gallio and oxalicaoids.
9. Aotivation analysis witha Pu-Be neutron source
10. Activation analysis byphotoneutron counting.
11* Behaviour of thorium indimethyl eulphoxide - achronopotentiometricstudy.
S.Y.Shetty
M.R.DhaneshwarR.G.BhanesbwarL.R.Zarapkar
Current Sci.,11, 675 (1972)
Current Sci.,il, 873 (1972)
T.P.Radhakrishrian Ind. Acad. Sci.,A.K.Sundaram 75, 278 (1972)
FushparajaM.SudersananA.K.SundaramM.SudersananA.K.Sundaram
M.R.DhaneshwarR.G.Ehaneshwar
Curr. Sci., 41,633 (1972)
Proc. Ind. Acad. Sci.,25 v. 151 < )
Analyst., 9JL, 620(1972)
R.K.Iyer Anal. Chim. Acta.,K.R.Krishnamoorthy 60, 454 (1972)M.Sankar Dae
S.P.Biswas Ind. J. Chem..T.S.Krishnamoorthy 10, 870 (1972)Ch.Venkateswarlu
P.B.PawaskarG.Rami ReddyM.Sankar D
K.P. ManiM.Sankar Das
P.ChoudhuryK.A.Khasgiwale
Ind. Jour. Tech.,!0 t 80 (1972)
Ind. Jour. Tech.,10, 218 (1972)
Jour. Eleotroanal.Chem. 4^, 444 (1972)
SYMPOSIA/CONFERENCE
1. Trace element geochemistry of the basaltic-and associated rocks of Kt.Girnar, WesternIndia: A preliminary report.
2. Studies on the -cation-exchange behaviourof 12-molybdophosphates of monovalentcations. Part I I I . Dehydration reactionsof some 12-molybdophosphateB.
3 . The effect of laser irradiation on goldelectrode in potentiometric t i trat ions.
4. Studies with iodide specific ionelectrode.
5. Comparative study of stripping analysisusing hanging mercury drop.and metalwire amalgam electrodes.
6. Potentiometrie.investigation of some .mixed complexes of thorium.
7. Spin transmission mechanism in adducts ofnickel(II) diketones with tertiary bases.
8 . Amines as extractants.
9. Growth of hair and the trace elementprofile: A study by sectional analysis.
A.V.MuraliM.Sankar Das
S.R.DesalM.Sankar Das
M.E .DhanesbwarR.G.DhaneshwarL.G.Pandit
M.R.DhaneshwarR. 5. Dhaneshwar
H.G.Dhane shwarM.M.PalrechaL.R.Zarapkar
S.Y.ShettyR.M.Sathe
H.M.DhingraB.Maiti
Ch.Venkateswarlu
S.GangadharanV.V.LakshmiM.Sankar Das
1972 Int. Symp. on RecentResearches and
Applns. in Geochem.
DAE Chem.Syap. 1972Aligarh.
Technical Session on Electro-chemical Instrumentation,Madras.
- do -
- do -
Convention of Chemists,1972,. Allahabad.
- do >*•
Plenary lecture at the SolventExtraction Symp. Santiniketan.
Int. Conf. on ForensicActivation Analysis.
- 1 4 1 -
BARO REPORB
1. On the uae of the fluoride ionsens i t ive eleotrode.
2 . Sett ing up of Techtron AA-4 ASflame emission, atomio absorp-t lon and fluorescence epectro-meter.
N.MahadevanR.M.Sathe
P.MurugaiyanS.NataraJanCh.Venkateewarlu
BARC/i-234
BARC/4-187
APPENDIX IV
NameB of students who have submittedtheir t h e s i s and obtained degrees
Candidate University Decree
M.Sudersanasv A.K.Sundaram Bombay M.Sc.
10.0
0.11
U- 334 ACTIVITY,COUNTS/ 300 pfl/hr
Fid. X CALIBRATION CURVE WK ISOTOPIC ANALYSIS OP URANIUM
NCUTR0N PRt-AMfklVIKR
HA SOI •CM
MAIN
AMPLIFIERPA *2O P
SUfPVYHV got 0
EIU6l.CC
AHAVSCA
DECASCAVDS 3
PREiTIMCCT 4-
UAHMCV
to
tOE.ER
setR.
53
CADMIUMftMlCV.0
| \ J _^\ * /> !*.%.\^'| "f J^\
7 \
SILtCA SAHVU
CUIDt TUBC
•RASS «r
PARAFFINMODERATOR
S NKOTKOUDttCCTOR
NtUTRft*
ILEADStnCtD
RABBIT IM COUHtiMfi
POSlTtQM
FIQ. B DELAYED NEUTRON DETECTOR AND ASSOCIATED
ELECTRONICS
0.9
0.2
01
0.4
0 DEPTH DISTRIBUTION COMPUTED*
COUNTS vs ENEROY
RIGHT HAND ORDINATE
8 1.2 1.6 2.0PTH IN MICRONS
0.9
0.2
3
0.1
1.9B 1378 1.4 1.426 1.46 1.476 1.6ENERGY < £ „ • ) MEV
FIG. n DEPTH DISTRIBUTION OF FLUORINE IN % fclRCALOYFOIL
I
VOLTS vs. S.C.E.
1.2 1.0 0.9 0.6 0.4 0.2 0PI©. S IMPURITY ANALYSIS OP SODIUM METAL BY STRIPPING POLAROORAPHV
pH • 2.0
METHANOL : CURVE 1 - NIL i CURVE 2-30 V.; CURVE 3 - 80 V.
HORIZONTAL SCALE FOR VOLTAGE SHIFTED 8Y-0 .2 AND 0.4VFOR 2 AND 3
0 0.2 0.4 0,6 0.8 1.0 1.2 1.4V—••
FI0.S: TITANIUM (IV) REDUCTION IN WATER - METHANOL MIXTURES
TIME, secondsFIG.SI CHRONOPOTENTtOMETRY AND CURRENT-REVERSAL CHRONOPOTENTIOMETRY OF EUROPIUM (Iff) IN
0.101M
-0.4 -0.6 -0.8
POTENTIAL, VOLTS
-1.4
FIG. SB CYCLIC VOLTAMMOGRAM OF Hg 2 * REDUCTION
1 - 0.1M KCNS / 2 - 0.01M HMOj (Au/Pt/8CE)
9 - 0.»4B pc /ml Ha2*/ 4 - TAP WATER
•o.a
•0.6
Cf«.B8 ANODIC STRIPPING CURVES OP MERCURY (S)
t i?* '• O.SmMMEDIUM-0.2 MNoCIO4
SCAN RATE < 2OmV/Mc.
0.4 0.6 O.aPOTENTIAL, VOLTS
P » . B CYCLIC VOLTAMKCTRV OP I n 3 * REDUCTION
t ( l A '
90
20
VOLTAMMETRY
I T '
- I — mM0 O.B 1.6 2.4lit IN 0.2M NaCIOj} v > 20mV/«*c.
120
80
40
CYCLIC
a **O °
•
VOLTA
V
'METRY
0.2. 0.4VOU/we
0.6
40
20
CHRONOPOTENTIOMETRY
0.8 1.6 2.4mMIn CONCENTRATION IN 0.2M NaCI04
CHRONOAMPEROMETRY
40
20
0.8 1.6 2.4 mMCONCENTRATION
FIG. X INDIUM REDUCTION USING DIFFERENT TECHNIQUES
CURVE 1 WITHOUT IRRADIATION2 _ | N p U T ENERGY 800 JOULES NO. OF SHOTS-33 - n » 625 '• « •• « 34 - » i, 828 • « « « 6
800
400
US
Ui
K
"300
200
^* % o —~o
21 22 23 24 2S 20 27 28-111 22 23 24 25 26 27 28 29-1Iff -22 23 24 26 26 27 28 28
22 23 24 2ti 7A 37 28-E
. XI EFFECT OF LASER IRRADIATION ON GOLD ELECTRODE IN ACID-BASETITRATIONS
270500 1000 1S00 2000 2B00 3000
INPUT INEROY • JOULES3600 4000 4600
FIO. H EFFECT OF TOTAL INPUT ENERGY ON POTENTIAL JUMP AT END POINT
20
30 IS
20 10
0 0.2 0.4 0.9 0.8ml
1ml • 7.15 jig Pb2*
ELECTROLYSIS TIME ImL, As5.5 JC10'2 sq.cin.CHMDE)
0 0.2 0.4 0.6 0.8 ml
1ml a 7.85jig Pfe
ELECTROLYSIS TIME ImL (Au-Hg)
A s 0.5 sq. cm.
FIG. XBt CAU8RATI0N CURVES OBTAINED WITH HMDE ft GOLD-WIRE AMALGAM ELECTRODE
CURVE 1 - OOLO AMALGAM WIRE ELECTRODE FOR ESTIMATIONOP Pb3* IN GRANITE ORE. Et-Bml./ Cs . 28 /JA
CURVE 2 • MMDE FOR Pb2* ESTIMATION IN GRANITE61 • 9ntl. Cs • 2BfiA
CURVE 3 -1.0WB r Pb2*/ml STO. SOLUTION ON AulHg) El • BmtC« 2 8 A
-o.i
WC. I B COMPARISON OF GOLD AMALGAM WIRE ELECTRODE ft HANGINGMERCURY DROP ELECTRODE
APPARATUS -• ELSGTROSCAM - 30
EL.EC7RS3S SYSTEM: A u / P t / M o
INITIAI. V0LTA6E : 0.00V
CHART SPEED : 12~/M!NUTE
i m M C d 2 * • 0.01 MKNO
O.lmM Cd2 \0.1M KNO3
0.1N H2SO4
1mM Cd • 0.1M KNO3 * 50 % FORMAMIDE
VOLTAGE a 1 x 0.2 VFIG. X I CYCLIC VOLTAMMETRY OF N0~ IN PRESENCE OF Cd2*
SOLID LINES i CONCENTRATION INDASHED LINES ' OUANTITV OF ELEMENT, ugm/ STRAND/10* K SCALE
30
26
20
16
10
6
Ne Mn
h-.-J. . . J
3000
2500
2000
1600
1000
600
Zn
12
10
8
9
4
2
u
1200
1000
600
600
400
200
Hg
20 40 60 80 100DISTANCE (cm)
120
100
60
60
40
20
1
I
20 40 60 80 100DISTANCE (cm)
FIG. SECTIONAL ANALYSIS OP A HAIR SAMPLE
•MWl
PUMP*
•U6MCTK MtMMtK
FIG. ZED DIAGRAM OF SPARK SOURCE MASS SPECTROMETER
SAMPLEC0+002*H20
so2*o2
CO«.CO2»O2
HjO
CO2*O^
MjO
CO2*O2
INDUCTION SULPHURTRAP CONVERTER
MOISTURETRAP
MOLECULARSIEVE
HEAT
VOLTMETERTHERMAL
CONDUCTIVITYCELL
LECO CARBON ANALYSER
JSCfclA-TOR
JONES CONDUCTIVITY BRIDGE
