Water Technology 3
Transcript of Water Technology 3
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Alkalinity:
Due to the presence of Caustic alkalinity(OH-- & CO3
-2)
Temporary hardness(HCO3-)
These can be estimated by titration against standardacid
The determination is based on
1. OH- + H+ H2O
P2. CO3
-2 + H+ HCO3-
M3. HCO3
- + H+ H2O + CO2
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Reaction 1 &2 take place in presence ofPhenolphthalein indicator
All Reactions of Methyl orange indicator
In presence of phenolphthalein indicatorcomplete neutralization of hydroxide & halfneutralization of carbonate takes place.
After phenolphthalein end point completeneutralization of carbonate and all bicarbonates
takes place.
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
The possible combinations of alkalinity
OH
-
CO3-2
HCO3-
CO3-2 & HCO3
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CO3-2 &OH-
OH- & HCO3- ions does not exist
CO3-2, OH- & HCO3
- ions does not exist
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Procedure:
100 ml of water sample
add 2-3 drops of phenolphthalein
titrate against N/50 acid from the burette
pink colour is discharged
continue the titration with methyl orange indicator
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
--2(M-P)2P-MP>M/2
M-2P2P--P
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Estimation of chloride:
Usually it presents as NaCl, MgCl2, CaCl2 Chloride conc. Over 250ppm is not desirable for drinking
It is estimated by titrating against standerd AgNO3
Potacium chromate is indicator
PH is 7-8
AgNO3 Ag+ + NO3-
Ag+ +Cl- AgCl (White)
Ag+ + CrO4-2 Ag2CrO4 (red)AgNO3 + K2CrO4 KNO3 + Ag2CrO4
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
K2CrO4 indicator is prepared by dissolving 5 gmsof K2CrO4 in 100 ml distilled water.
Procedure:
50 ml of given sample
add 1 ml of freshly prepared K2CrO4
titrate against AgNO3 from the burette while shaking
colour changes from yellow to red and red colour persists
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Blank Titration:
The above procedure is repeated with distilled waterCalculations:
Sample silver nitrate solution
V1N1 = V2N250 x N1 = V2 x 1/50
N1 = V2 x 1/2500
Strenth of chlorine = 35.5 x V2 x 1/2500 gm/L
=1000 x 35.5 x V2 x 1/2500 mg/L
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Dissolved oxygen
It is based on the oxidayion of KI by dissolved oxygen
Liberated Iodine is titrated against standard
sodiumthiosulphate using starch as final indicator O2 in water is not capable of reacting with KI, as an
Oxygen carrier (Manganese hydroxide) is used
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
KOH + MnSO4 Mn(OH)2 + K2SO4
Mn(OH)2 + O2 MnO(OH)2Basic manganic oxide
MnO(OH)2 + H2SO4 MnSO4 + H2O + (O)
KI + H2SO4+ (O) K2SO4 + H2O + I2
Na2S2O3 + I2 NaI + Na2S4O6
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Some times water may has nitrites sulphites and
undergo oxidation in presence of O2 This can be avoided by adding NaN3 to the water
sample
NaN3 + H2SO4 N3H + Na2SO4
HNO2 + N3H N2O + N2 + H2O
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WATER TECHNOLOGY I
ANALYSIS OF WATER
Dr. E. LaxminarayanaMail: [email protected]
Procedure:
Collect 250 ml of water avoiding contact with air add 2 ml of MnSO4 solution + 2ml of KI
stopper and shake thoroughly
add 20ml of H2SO4 withdraw 100ml and titrate against Na2S2O3 using
starch as indicator
If the volume of hypo is V ml the dissolved oxygen = 8
x V ppm