Doctoral thesis summary · The first general objective of the thesis is to address efficient...
32
1 Craiova University Doctoral School of Sciences Chemistry domain Doctoral thesis summary Scientific adviser Univ. prof. dr. Alexandru Popescu Univ. prof. dr. ing. Adriana Samide (tutelle) PhD student Chim. Cristian-Ovidiu Neamțu 2019
Transcript of Doctoral thesis summary · The first general objective of the thesis is to address efficient...
1
Craiova University Doctoral School of Sciences
Chemistry domain
Doctoral thesis summary
Scientific adviser
Univ. prof. dr. Alexandru Popescu
Univ. prof. dr. ing. Adriana Samide (tutelle)
PhD student
Chim. Cristian-Ovidiu Neamțu
2019
2
Craiova University
Doctoral School of Sciences
Chemistry domain
Electrochemical transformation of organic
contaminants in the presence of specific anions
for experimentation of some wastewater
analysis/depollution models
Scientific adviser
Prof. univ. dr. Alexandru Popescu
Prof. univ. dr. ing. Adriana Samide
PhD student
Chim. Cristian Ovidiu Neamtu
3
TABLE OF CONTENTS Chapter I
The current state of knowledge in the field of electrochemical degradation
of organic pollutants
1.1. Electrode processes encountered in electrochemical degradation
1.2. Studies on the electrochemical degradation of medicines present in polluted waters
1.3. Studies on electrochemical depollution of polluted water with food additives
1.4. Studies on the use of electrochemical methods in the treatment of polluted waters with
organic pesticides
1.5. Kinetic studies on the electrochemical degradation of organic compounds
1.5.1. Introduction to chemical kinetics
1.5.2. Kinetics of zero-order reactions
1.5.3. Kinetics of first order reactions
1.5.4. Cinetica reacțiilor de ordin II
1.6. Kinetic studies on the electrochemical degradation of compounds with pharmaceutical
action in polluted waters
1.7. The study of the kinetics of electrochemical degradation of food additives from aqueous
solutions
1.8. Kinetic studies on the use of electrochemical methods in the treatment of polluted waters
with organic pesticides
Conclusions
Original contributions
The objectives of the doctoral thesis
Chapter II
Research methodology
2.1. Methods and equipment used in research
2.1.1. Electrochemical methods
2.1.2. UV-Vis spectrophotometric analysis
2.1.3. Thermal analysis
2.2. Materials and methods of operation
2.2.1. Study of the processes of degradation of retinyl palmitate (RP)
2.2.2. Study of the processes of electrochemical degradation of 5-fluorouracil (5FU)
2.2.3. The study of the processes of electrochemical degradation of the food additive
Chocolate Brown HT (BHT)
2.2.4. Study of the processes of electrochemical degradation of the food additive tartrazine
(TRZ)
2.2.5. Study of the electrochemical degradation processes of pesticides acetamiprid,
emamectin, imidacloprid and propineb
Chapter III
Study of electrochemical degradation of biologically active compounds
4
from the class of medicines
3.1. Study of the electrochemical behavior of Vitamin A in hydroalcoholic solution
3.1.1. Spectrophotometric study of the interactions between retinyl palmitate and colloidal
silver nanoparticles in the presence of chloride and nitrogen anions
3.1.2. Study of the electrochemical behavior of retinyl palmitate in the presence of nitrogen
anions
3.1.3. Study of the mechanism of electrochemical degradation of vitamin A
3.1.4. Study of the electrochemical stability of vitamin A in the presence of chloride anions
3.2. Study of the electrochemical and thermal behavior of the anti-tumor 5-fluorouracil
drug (5FU)
3.2.1. Study of the electrochemical degradation of 5FU on titanium electrodes
3.2.2. Study of the mechanism of electrochemical degradation of 5FU
3.2.3. Study of the thermal degradation of 5FU in an inert atmosphere
Conclusions
Chapter IV
Electrochemical, kinetic and thermal studies on
degradation of food additives
4.1. Study of the processes of electrochemical and thermal decomposition of the food
additive Chocolate Brown HT (E155)
4.1.1. The study of the thermal degradation of the food additive Chocolate Brown HT
4.1.2. Study of the electrochemical stability of the food additive Chocolate Brown HT by
cyclic voltammetry
4.1.3. Study of the electrochemical stability of the food additive Chocolate Brown HT by
spectrophotometric assisted electrolysis
4.1.4. Kinetic studies of electrochemical degradation of the food additive Chocolate Brown
HT in the presence of halide anions
4.2. Study of the electrochemical degradation of tartrazine in aqueous solution
4.2.1. Direct electrochemical degradation of tartrazine
4.2.2. Indirect electrochemical degradation of tartrazine
Conclusions
Chapter V
Reducing the ecotoxicity of pesticide-contaminated waters
by electrochemical methods
5.1. Electrochemical and thermal degradation of acetamiprid
5.2. Study of the electrochemical and thermal decomposition of emamectin
5.3. Electrochemical and thermal degradation of imidacloprid
5.4. Study of the electrochemical and thermal behavior of propineb
Conclusions
General conclusions
Bibliography
Introduction The industrial activities, in the vast majority, generate, as a result of the technological
processes, waste water with a very high content of organic compounds, in particular, those of
the food, pharmaceutical, cosmetic and textile industry. This fact requires the necessity of
implementing methods of treatment of industrial and domestic effluents with the purpose of
reintroducing these waters into the natural circuit without having a negative impact on the
5
underwater or terrestrial flora and fauna. The current strategies regarding environmental
protection involve the use of waste treatment processes but also the development of more
efficient processes that do not have harmful effects on the environment.
Protecting the quality of Europe's water resources is one of the priorities of the
European Union. European Parliament has developed certain wastewater treatment directives
(UWWTs) that require EU Member States to invest in urban waste collection and treatment
infrastructure, nitrate directives, which require farmers to control the quantities of nitrogen
fertilizers used and Directives on Pollution Prevention and Control (IPPC) with a view to
minimizing pollutants discharged from industrial activities.
(https://eur-lex.europa.eu/legal-content/RO/TXT/PDF/?uri=CELEX:32000L0060&from=RO)
The application of biological methods in the treatment of polluted waters with organic
contaminants is not always possible due to their action on environmental crops. The use of
physico-chemical methods such as oxidation with ozone or chlorine dioxide, besides a low
efficiency, raises major problems regarding the transport and storage of the reactants.
The disadvantages of the classical depollution methods have been minimized by
introducing new electrochemical methods that allow the efficient degradation of organic
pollutants up to the values of the concentrations that fall within the values imposed by the
environmental legislation in force, concentrations at which the aquatic or terrestrial
ecosystems where discharged are not affected. The application of electrochemical
technologies to the degradation of organic pollutants from wastewater benefits from
advantages such as low costs, ease of implementation and use, compatibility with the
environment.
The new technologies for waste water treatment take into account both direct
electrochemical oxidation and indirect or mediated electrochemical oxidation, as evidenced
by the publication of numerous specialized studies. Some of these electrochemical
technologies are comparable to the conventional ones in terms of cost and efficiency.
The main electrochemical technologies developed in this regard are electrooxidation,
electrocoagulation, electroflocculation and electrodeposition. Electrooxidation is achieved by
the action of species with a highly oxidizing character, similar to chemical oxidation, with the
exception that these species are generated electrochemically in situ and lead to a high
efficiency of mineralization of organic pollutants.
In order to develop new methods, which are more efficient, but which also have low costs, the
use of new experimental conditions and the optimization of methods by the complete and
complex study of the factors that influence the electrochemical processes of degradation of
organic pollutants have been used. Of these factors, the most important are: the nature and
composition of the electrodes (stable dimensional oxide electrodes, Pt, C and graphite, boron
doped diamond, SnO / SnO2, PbO / PbO2, Sb2O5), the nature and composition of the
electrolyte solution, pH, value of current density, temperature, nature and concentration of the
supporting electrolyte, presence of catalysts or photocatalysts, development of electro-Fenton
and photoelectro-Fenton methods or advanced electro-oxidation processes. In general, an
ideal electrode material in the degradation of organic pollutants must have a high oxygen
evolution potential for the secondary oxygen formation reaction to be excluded. For this
reason, different types of oxide electrode materials based on iridium, ruthenium, tin or lead
have been tested. In each particular case, these electrode materials must be tested, in order to
determine the electrocatalytic activity, oxidation stability and durability with the purpose to
determine the efficiency of use for a certain process of electrochemical degradation of an
organic pollutant.
The doctoral thesis highlights the results of the research activities carried out during
the doctoral period and is based on a considerable number of experimental determinations on
the electrochemical degradation of some organic pollutants in the class of medicines, food
additives and pesticides.
6
The experimental results obtained, published in ISI / BDI specialized journals or
communicated at national and international conferences can be used in the design of
electrochemical systems in order to improve the parameters of degradation of organic
pollutants.
The research activity pursued a broad characterization of the electrode processes that
occur at the electrochemical degradation of the studied organic pollutants. Thus, comparative
experiments were performed under different conditions on electrodes made of different
materials.
The work is structured in two parts: the literature part and the original contributions
part.
I. The current state of knowledge in the field
Pollution has features that affect both the environment and man. Pollutants are substances,
organic or inorganic, that once reached the environment (water, air, soil) have at least one
harmful effect on the ecosystem.
The literature section includes a chapter. Chapter I refers to studies on electrode processes that
occur during electrochemical degradation of organic pollutants. The electrode processes
leading to the in situ electrochemical generation of the highly oxidizing active species
responsible for the electrooxidation of the pollutant molecules are presented and the results of
the research on the electrochemical degradation of some organic pollutants in the class of
drugs, food additives and pesticides. Also, both kinetic notions and certain kinetic approaches
on decomposition reactions are presented, as well as the ways to optimize pollutant
degradation methods.
II. Original contributions
The first general objective of the thesis is to address efficient electrochemical methods for
investigating the stability of residual organic compounds from medicinal / industrial /
wastewater. Therefore, the results of the study on the interactions between Vitamin A and
colloidal silver in the presence of Cl- and NO3- i anions on the electrochemical stability of
cytostatic 5-fluorouracil using cyclic voltammetry, constant current electrolysis and UV-Vis
spectrophotometry are presented. Within the second general objective of the thesis, the
mechanisms of electrochemical transformation / decomposition of both vitamin A on
platinum electrodes and the cytostatic 5-fluorouracil on titanium electrodes have been
elaborated.
Chapter IV systematizes the results obtained for the thermal and electrochemical
degradation processes of two dyes used as food additives, namely chocolate brown HT (E155)
and tartrazine (E102). An extensive study on the thermal and electrochemical degradation of
the additive E155 was performed; the degrees of electrochemical degradation were
determined in the presence of different halide anions using platinum electrodes; methods such
as cyclic voltammetry and electrolysis at constant current density, in dynamic regime, coupled
with UV-Vis spectrophotometry were used. The thermal stability of the E155 dye was studied
by thermogravimetric and calorimetric methods; the thermodegradation mechanism was
proposed; the optimal parameters for the decontamination of the waste water were determined
(the composition of the environment, the ratio between concentrations - selective anion / dye,
the pH of the environment, the temperature). The study is completed by calculating the kinetic
parameters of E155 electrochemical degradation, by modeling the experimental data
corresponding to the zero, first and second order kinetic models. Also in this chapter are
presented the results of the study of the electrochemical behavior of tartrazine in aqueous
solution.
The results of studies on reducing the toxicity of pesticide-contaminated waters by
electrochemical methods are presented in Chapter V. They predict the behavior of pollutant
molecules in the presence of strong oxidants such as electrochemically generated hypochlorite
anions during electrode processes. The investigation was performed by cyclic voltammetry
and electrolysis at constant current, in association with UV-Vis spectrophotometry. The
7
pesticides studied, namely: acetamiprid, emamectin, imidacloprid and propineb were
thermally analyzed, in order to determine the temperature ranges corresponding to the
stability / instability of these pesticides.
The objectives of the doctoral thesis
General objectives O.1. Addressing efficient electrochemical methods, such as electrolysis at constant current
density and cyclic voltammetry, for studying the stability of residual organic
compounds from medicinal/ industrial /wastewater: organic nutritional compounds,
dyes and pesticides.
O.2 Proposing mechanisms for electrochemical transformation/decomposition of organic
compounds detected in small concentrations in wastewater.
Specific objectives O.S.1. Coupled systems like Vitamin A-silver nanoparticles analyzed by UV-Vis
spectrophotometry and cyclic voltammetry.
O.S.2. Electrochemical stability of drugs, e.g. 5-fluorouracil.
O.S.3. Study of the stability of some dyes, such as Brun HT using electrochemical methods
associated with UV-Vis spectrophotometry and thermal analysis.
O.S.4. Reducing the toxicity of pesticide-contaminated waters by electrochemical methods.
Motivation of the research topic
a. Control of the purity of wastewater contaminated with different organic compounds.
b. Controlling the stability of certain vitamins in order to detect decomposition products with
toxic potential on the human body; designing a warning model for the storage of
contaminated water.
c. Discoloration of waste water polluted with certain chemical dyes; approaching a model of
dye removal.
d. Decontamination of wastewater containing pesticides in residual quantities; approaching a
model for reducing the toxicity of wastewater.
e. The beneficial effects of Vitamin A versus the potentially toxic effects of decomposition
compounds require the restriction of the discharge of contaminated water prior to
purification.
f. Large-scale use of colorants in the food industry.
g. Use of pesticides in agriculture, generally in the form of solutions.
Study of electrochemical degradation of biologically active compounds in
the drug class
Study of the electrochemical behavior of Vitamin A in hydroalcoholic solution
Spectrophotometric study of the interactions between retinyl palmitate and
colloidal silver nanoparticles in the presence of chloride and nitrogen anions
8
Figure 1 shows UV-Vis spectra of retinyl palmitate hydroalcoholic solution and retinyl
palmitate hydroalcoholic solutions containing Cl- or NO3- ions, in the absence and presence
of silver nanoparticles (nAg).
Retinyl palmitate (RP) has two absorption maxima:
- a well defined maximum at the wavelength of about 325 nm;
- a maximum split at 250 nm, which corresponds to a high absorbance value.
Colloidal silver nanoparticles (nAg) have a maximum absorption at 400 nm
o The chloride anion causes a large increase in the absorption maxima of the RP and a
significant decrease in their intensity.
o Between nAg, RP and Cl-, multiple strong interactions are established, evidenced by
the disappearance of the two absorption maxima of the RP, the cleavage and the
displacement of the maximum absorption of nAg at wavelengths greater than 400 nm.
o The gradual increase of the absorbance at wavelength values less than 300 nm can be
due to the formation of intermediate species between RP and nAg and / or Ag +.
The superposition of the multiple interferences detected at 400 nm highlights the
spontaneity of the interaction between retinyl palmitate and colloidal silver nanoparticles,
with the formation of RP_nAg complexes, in the solution containing chloride anions.
Nitrogen anions produce a shift of the absorption peaks of the RP to smaller
wavelengths:
• 325 nm 300 nm
• 250 nm 230 nm
0
1
2
3
4
5
200 300 400 500 600
ab
sorb
an
ța
lungime de undă / nm
a RP
RP_NaCl
RP_NaCl_nAg
0
1
2
3
4
5
200 300 400 500 600
abso
rban
ța
lungime de undă / nm
b RP
RP_NaNO3
RP_NaNO3_nAg
0
1
2
3
4
5
200 300 400 500 600
abso
rban
ța
lungime de undă / nm
c RP
nAg
RP_nAg
9
Figure 1. UV-Vis spectra of the alcoholic solution of RP 5 • 10-6 mol • L-1; a - in the absence
and presence of chloride and nAg anions; b - in the absence and presence of nitrogen anions
and nAg; c - in the absence and presence of nAg in a concentration of 500 mg • L-1.
In the presence of colloidal silver nanoparticles, the electrolyte solution absorbs
strongly at 400 nm, which denotes reduced interactions between RP and nAg.
The formation of complexes between retinyl palmitate molecules and colloidal silver
nanoparticles explains the disappearance of the maximum at 250 nm and the occurrence of the
two absorption maxima at 400 nm and 325 nm.
Study of the mechanism of electrochemical degradation of vitamin A
CH2 CH2 + H2O
-H+
CH2
OH -e -H+
CH2
Ointermediar 5,6-epoxi
+ H2O
-H+
CH2OH
O-e
CH2OH
O
HC CH2OH
+ H2O
-e -H+
+ 2H2O
-4e -3H+ -CO2
OH
OH
OH
OH
CH2
OH-e
CH2
OH
H3CC
OH
H3CC
OH
+ H2O
-H+ H3CC
OH
OH
-e -H2O H3CC O
+ H2O
-H+ CH3COOH- CO2
-2e -H+
CH3
+ H2O
-H+CH3OH
+ H2O
-4e -4H+HCOOH
-2e -2H+-CO2
+ H2O
-e -H+ H3CC
OH
H3CH2C
CH2OH
CH3COOH / HCOOH / CO2 / H2O
10
HC CH2OH
+ H2O
+ H2O
+ H2O
+ H2O
+ 2H2O
+ H2O+ H2O+ H2O
+ H2O
+ H2O
+ H2O
+ H2O
+ H2O+ H2O
+ H2O
-e
-H+
-H+-H+
-H+
-H+
-H+
-H+
HC
HC
O O
-2e -2H+
-2e -3H+
-2e -3H+-2e -H+
-e -H+
-2e -2H+
-4e -4H+ -CO2-4e -3H+ -CO2-4e -4H+
-4e -3H+
-4e -3H+
-CO2
CCHO
OH
- CO2
- CO2
- CO2
H2C CH
O -CO2
HOH2C-e
-e
HOH2C
H3C
CHOH
CH3
HOH2C
H3C
CH HCCHOH
CH3OH
HOHOH2C
H3C
CH
O
OHCCHOH
CH3
HOOC CH
H3C
CH3CHO / CH3COOH / HCOOH / CO2 / H2OHCCOOH
H3C
Scheme 1. Mechanism of electrochemical degradation of retinyl palmitate
The nonatetraene intermediate has a high reactivity due to the four double bonds in its
molecular structure. At the same time, the existence of the delocalized π electron system can
lead to different electrochemical degradation mechanisms. A possible path of electrochemical
degradation is described by the mechanism attached.
UV-Vis spectrophotometry indicated a strong interaction between retinyl palmitate
molecules and silver nanoparticles, in the presence of chloride anions and lower interactions
in the presence of nitrogen ions.
The experimental results obtained by cyclic voltammetry show that the addition of
colloidal silver nanoparticles to the electrolyte solution leads to a considerable decrease of the
current density, followed by a significant change in the hysteresis form due to the interaction
between the vitamin A molecules and the silver nanoparticles.
Study of the electrochemical and thermal behavior of the anti-tumor
drug 5-fluorouracil (5FU)
Objectives proposed
1. Study of electrochemical degradation of 5FU on titanium electrodes.
2. Study of the mechanism of electrochemical degradation of 5FU.
3. Study of thermal degradation of 5FU in inert atmosphere.
11
-6
-4
-2
0
2
4
6
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
i /m
Acm
-2
E vs. Ag/AgCl,KCl /V
NaCl 0,9 %
NaCl 0,9 %_5FU
0
1
2
3
200 300 400 500
abso
rban
ța
lungime de undă / nm
NaCl 0,9 %
NaCl 0,9 %_5FU
NaCl 0,9 %_5FU_după CV
Figure 2. Cyclic voltammograms recorded on Ti electrode in 0.9% NaCl solution, in the absence and in the
presence of 5FU 10-4 mol • L-1 scanning speed of 100 mV s-1 potential; UV-Vis spectra of 0.9% NaCl solution,
without and with 5FU 10-4 mol • L-1, before and after cyclic voltammetry.
The presence of the drug in the saline solution at the cyclical polarization of the titanium
electrode determines the following effects:
• Changing the shape of cyclic voltamograms.
• Decreased anodic current densities.
• Extend the passivity range by approximately 0.2 V
During the cyclical polarization of the titanium electrode, the 5-fluorouracil molecules
participate in the processes from the electrode / electrolyte interface, the electrochemical
activity of the drug being revealed by the complete disappearance of the absorbance trace
from the value of the 300 nm wavelength and the decrease of the absorbance values.
corresponding to wavelengths less than 250 nm.
Study of mechanism of electrochemical degradation of 5FU
5FU molecules participate on the titanium electrode surface in the oxidation,
tautomerization and opening processes of the pyrimidine ring, with the formation of two
intermediate fragments (A and B), as shown in Scheme 2.
NH
HN O
F
O
-e -eNH
HN O
F
O
NH
NH O
F
O
HN
H
F
O
HN
C O
HN
H
F
O
HNC O
fragment Afragment B
12
HN
H
F
Ofragment A
H
F
O
+H2O-e -H+
-NHOH+
-e -H++H2O
+2H2O
-3e -3H+
-CO2
OH H
F
OH
O
H
-F- -H+glyoxal / glyoxylic acid /oxalic acid / CO2 H2O
+H2OHN
C O
fragment B
+2H2O
-3e -3H+ N CO
H
HO
O
HN=O-H+ -CO2 -3e -3H+
NO2
Scheme 2. Mechanism of electrochemical degradation of 5FU
The cyclic voltammetry of the titanium electrode demonstrates that the 5-fluorouracil
molecules used as an antitumor drug are electrochemically active.
Spectrophotometric analysis of the electrolyte solution performed comparatively,
before and after recording the cyclic voltamogram indicates the change of the absorption
maxima, demonstrating that the 5 FU molecules are electrochemically degraded.
Electrochemical, kinetic and thermal studies on the degradation of
food additives
The study of the electrochemical stability of the food additive
Chocolate Brown HT by cyclic voltmetry
The electrochemical processes that occur on the surface of the platinum electrode in
aqueous solutions of BHT, containing NaX support electrolytes are correlated with the
processes of the X- ions from the electrode / electrolyte interface. The electrochemical
degradation of organic BHT molecules can occur through: i) direct electrochemical
degradation (heterogeneous) by directly participating in the processes on the surface of the
electrode, as in the case of using inert support electrolytes, such as fluoride anions; ii) indirect
(homogeneous) electrochemical degradation in solution, due to the electrochemically
generated active species, as is the case with the use of active support electrolytes, such as
chloride, bromide and iodide anions.
Figure 3 shows the cyclic voltamograms on Pt electrode in studied electrolytes, in the
absence and in the presence of BHT.
-20
0
20
40
60
80
-1.5 -1 -0.5 0 0.5 1 1.5 2
i / m
A c
m-2
E / V vs. Ag/AgCl,KClsat
a NaF
NaCl
NaBr
NaI
-20
0
20
40
60
80
-1.5 -1 -0.5 0 0.5 1 1.5 2
i / m
A c
m-2
E / V vs. Ag/AgCl,KClsat
bNaF_BHT
NaCl_BHT
NaBr_BHT
NaI_BHT
Figura 3. Cyclic voltammograms recorded on Pt electrode in: a - NaX 10-1 mol • L-1; b - NaX 10-1 mol • L-1
containing BHT 10-4 mol • L-1; (X = F, Cl, Br, I); v = 100 mV • s-1
In the presence of fluoride anions, peaks of the low intensity anodic current densities
are recorded, in the potential range from -0.5 V to 1.0 V, due to the adsorption and
electrooxidation of the BHT molecule on the electrode surface. In this area of potential, the
fluoride anions are electrochemically inactive and therefore, the formation of the adequate
active oxygenated species cannot take place. In the solution, which contains chloride anions,
the slight increase in current density on the corresponding cyclic voltamogram is correlated
with the oxidation of chloride ions, which generates hypochlorite species in the proximity of
the electrode. In contrast, the presence of bromide ions in the electrolyte solution increased
the anodic and cathodic current densities in the potential range between -1.0 V and 0.0 V.
13
The study of the electrochemical stability of the food additive Chocolate Brown HT by
spectrophotometrically assisted electrolysis
Electrolysis was carried out at constant current density of aqueous solutions containing
Chocolate Brown HT food additive to test the effect of different electrolytes supporting NaX
(X = F, Cl, Br, I) on electrochemical color removal. UV-Vis spectrophotometry can be
successfully used to observe the absorbance variations of photosensitive species during
electrochemical degradation processes.
Figure 4. shows the UV-Vis spectra of the aqueous BHT solutions recorded at
different times of the electrolysis process..
0
1
2
3
200 400 600 800
abso
rban
ța
lungime de undă / nm
a0 min
60 min
0
1
2
3
200 400 600 800ab
sorb
anța
lungime de undă / nm
b 0 min
10 min
Figure 4. UV-Vis spectra of aqueous solutions of BHT 10-4 mol L-1, NaX 10-1 mol L-1 recorded at different
electrolysis times; X = F - a, Cl –b; current density = 50 mA cm-2
The UV-Vis spectrum of the aqueous dye solution is characterized by the presence of
four maximum absorption values; three maximum values of absorption, well defined, at the
values of the wavelengths: 315 nm, 492 nm, 630 nm and a maximum of reduced intensity at
the wavelength 415 nm.It is known that the electrochemical treatment of organic pollutants
has superior efficiencies in the presence of halide anions, due to the synergistic action of the
active electrogenated species (XO-).
Figure 5 represents the UV-vis spectra of the aqueous solutes of the food additive
recorded at different times of the electrolysis process, in the presence of bromide and iodide
ions.
0
1
2
3
200 400 600 800
abso
rban
ța
lungime de undă / nm
a0 sec
100 sec0
1
2
3
200 400 600 800
abso
rban
ța
lungime de undă / nm
b0 sec
0 sec
100 sec
100 sec
Figure 5. UV-Vis spectra of aqueous solutions of BHT 10-4 mol L-1, NaX 10-1 mol L-1 recorded at different
electrolysis times; X = Br - a, I –b; current density = 50 mA cm-2
We observe in Figure 5 a greater decrease of the absorbent values when the supporting
electrolyte was represented by sodium bromide, requiring 30-40 seconds for the total removal
of the dye. This attests to the high oxidation capacity of the oxygenated anions of bromine
(BrO-).
14
0
25
50
75
100
0 1 2 3 4 5
EC
R /
%
timp / min.
a
BHT_ClBHT_BrBHT_I
0
20
40
60
0 15 30 45 60
EC
R /
%
timp / min.
b
Figure 6.Variation of electrochemical color removal (ERC) as a function of time, for BHT degradation in the
presence of a-CL, Br, I anions; b-Fl
The waters contaminated with this additive must be treated with specific techniques for its
elimination. Figure 6 shows a maximum value for electrochemical color removal, when using
bromide and chloride electrolytes. In the presence of bromide ions (Fig. 6a), the time required
for total discoloration is less than 50 seconds, while for the electrolyte chloride, the time
required for total discoloration is 5 minutes. In the presence of iodine, the process of
electrolysis cannot be highlighted for more than 2 minutes due to the formation of iodine, so
that a value bigger than 18% is not reached. Due to its electrochemical stability, the fluoride
ions lead to a maximum electrochemical elimination value of the additive color of 60%, after
one hour of electrolysis (Fig. 6b).
The study of the kinetics of electrochemical degradation of the food additive
Chocolate Brown HT in the presence of halide anions
In order to determine the mode of electrochemical degradation of the food additive
Chocolate Brown HT, kinetic models of zero order, first order and second order were
obtained from the experimental data obtained by the spectrophotometric method.
The values of the velocity constants obtained for the electrochemical degradation of
the additive Chocolate Brown HT in the presence of the different anions are compared in
Table 1.
Table 1.The values of the velocity constants obtained for the electrochemical degradation of
the additive Cholocate Brown HT in the presence of different anions
anion Zero order First order Second order
F- exponential variation linear variation
k = 0,0142 min-1
exponential variation
Cl- linear variation
k = 0,468 u.A·min-1
exponential variation polynomial variation
Br- polynomial variation linear variation
k = 6,7476 min-1
exponential variation
I- linear variation
k = 0,4263 u.A·min-1
polynomial variation polynomial variation
The values in Table 1 indicate a maximum electrochemical degradation rate when in
the electrolyte solution the bromide anion is found and a minimum, in case of the use of the
fluoride anion. At the same time, the degradation processes arise from simple kinetic models
of zero or first order, without there being a similarity in terms of the electrochemical behavior
between any two anions.
15
The study of the electrochemical degradation of tartrazine (TRZ) in aqueous
solution
Direct electrochemical degradation of tartrazine Direct electrochemical degradation of food additive E102 (tartrazine; TRZ) was
studied by cyclic voltammetry associated with UV-Vis spectrophotometry, using sodium
sulfate and sodium chloride as the supporting electrolyte.
Figure 7 shows the cyclic voltamograms of the platinum electrode in sodium sulphate
solution 10-1 mol L-1 in the absence and in the presence of tartrazine 5.10-5 L-1. Figure 7b
shows the details of cyclic voltamograms at low values of current densities.
-50
-30
-10
10
30
50
70
-2 -1 0 1 2
i / m
A·c
m-2
E / V vs. Ag/AgCl,KCl
Na2SO4
TRZ_Na2SO4
a
Na2SO4
TRZ_Na2SO4
-3
-2
-1
0
1
2
3
-1.5 -1 -0.5 0 0.5 1 1.5
i / m
A·c
m-2
E / V vs. Ag/AgCl,KCl
b
Figure 7. Cyclic voltammograms of Pt electrode in Na2SO4 solution 10-1 mol • L-1 in the absence and presence
of TRZ 5 • 10-5 mol • L-1, 100 mV • s-1 [150]
Figure 7a shows that the two voltammograms are very similar and differ only at very
high values of anodic (> 1.5 V) and cathodic (<-1.0 V) overvoltages. At values of the working
electrode potential greater than 1.5 V, the values of the recorded current densities are much
higher when the electrolyte solution also contains the TRZ food additive; which shows an
intensification of the charge transfer processes at the electrode / electrolyte interface.
The UV-Vis spectra of the working solution containing tartrazine in concentrations of
5 * 10 -5 mol L -1 and Na2SO4 10 -1 mol L -1 before and after the cyclic volamogram recording
are shown in Figure 8.
The oxidation stability of tartrazine was also studied by coupling the electrolysis
method to constant current density with the spectrophotometric analysis of the electrolyte
solution at different time points from the beginning of the electrolysis process. The value of
the current density used in the electrolysis process was i = 50 mA cm -2, and the electrolysis
time of one hour. The UV-Vis spectra of the electrolysis solution, recorded from 10 to 10 min,
are shown in figure 8.
0
0.4
0.8
1.2
1.6
200 300 400 500 600
abso
rban
ța
lungime de undă / nm
înainte de CV
după CV
0
0.4
0.8
1.2
1.6
200 400 600 800
abso
rban
ța
lungime de undă / nm
0 min
10 min
20 min30 min
40 min
50 min60 min
Figura 8. UV-Vis spectra of TRZ 5 solution • 10-5 mol • L-1 and Na2SO4 10-1 mol • L-1, recorded before and after
cyclic voltammetry, UV-Vis spectra of TRZ 5 solution • 10-5 mol • L-1 and Na2SO4 10-1 mol • L-1, at different
electrolysis times (10 to 10 minutes).
16
Indirect electrochemical degradation of tartrazine
Indirect electrochemical degradation of tartrazine was studied by cyclic voltammetry
associated with UV-Vis spectrophotometry using sodium chloride as the supporting
electrolyte. Figure 9 shows the cyclic voltamograms of the platinum electrode in the solution
of sodium chloride 10-1 mol • L-1, in the absence and presence of tartrazine 5 • 10-5 mol • L-1.
The cyclic voltammograms of the Pt electrode show a decrease of the current densities in the
presence of the tartrazine molecules. The cyclic voltammogram recorded in the presence of
tartrazine indicates the emergence of a new maximum (1.4 V vs. Ag / AgCl, KCl) of the
current density, this being attributed to the electro-oxidation of the organic dye molecules.
-50
-20
10
40
70
-2 -1 0 1 2
i / m
A·c
m-2
E / V vs. Ag/AgCl, KCl
NaCl
TRZ_NaCl
a
Figure 9. Cyclic voltammograms of the Pt electrode in 10-1 mol NaCl solution • L-1, in the absence and in the
presence of TRZ 5 • 10-5 mol • L-1, 100 mV • s-1
The cyclic voltammograms of the Pt electrode (Fig. 9) show a decrease of the current
densities in the presence of the tartrazine molecules. Chloride anions are reduced to the
surface of the platinum electrode to form chlorine molecules, which react with water
molecules and form hypochlorite anions. Consequently, tartrazine molecules are indirectly
degraded by hypochlorite anions.
The UV-Vis spectra of the TRZ 5 solution • 10-5 mol • L-1, 10-1 mol NaCl • L-1, before
and after the cyclic voltamogram recording, show that the absorbance value decreases
significantly. After recording the cyclic voltamogram, the chromophoric system of tartrazine
is electrochemically degraded in about 75%, according to the UV-Vis spectra introduced in
Figure 10.
0
0.4
0.8
1.2
1.6
200 300 400 500 600
abso
rban
ța
lungime de undă / nm
înainte de CV
după CV
0
0.5
1
1.5
2
200 300 400 500 600
abso
rban
ța
lungime de undă / nm
0 min
0 min
0 min5 min
5 min
5 min
Figura 10. UV-Vis spectra of TRZ 5 solution • 10-5 mol • L-1 and 10-1 mol NaCl • L-1, before and after the cyclic
voltamogram recording, UV-Vis spectra of TRZ 5 solution • 10-5 mol • L-1 and 10-1 mol NaCl • L-1, at different
times of electrolysis
UV-Vis absorption spectra in the wavelength range (430 nm) indicate rapid
electrochemical degradation. After 2 minutes from the beginning of the electrolysis process,
the maximum absorption initially recorded at the wavelength of 430 nm, completely
disappears. UV-Vis absorption spectra in the small wavelength range (258 nm) indicate a
more complex process.
17
This indicates the formation of an intermediate species with increasing concentration
over time. In the saline solution the UV-Vis spectra show the disappearance of the initial
absorption peaks (258 nm and 430 nm) and the appearance of a new absorption peak (332
nm).
Reducing the ecotoxicity of pesticide-polluted waters by
electrochemical methods
Electrochemical degradation of acetamiprid
Figure 11 shows the cyclic voltamograms of platinum electrode in aqueous solution
containing 10-1 mol • L-1 sodium chloride, both in the absence and in the presence of
acetamiprid in a concentration of 10-4 mol • L-1.
-30
0
30
60
90
-2 -1 0 1 2
i / m
A·c
m-2
E / V vs. Ag/AgCl,KClsat
a NaCl acetamiprid_NaCl
-10
-5
0
5
10
-2 -1 0 1 2i /
mA
·cm
-2
E / V vs. Ag/AgCl,KClsat
b NaCl acetamiprid_NaCl
Figure 11.Cyclic voltammograms recorded on Pt electrode in 10-1 mol NaCl solution • L-1, in the absence and
presence of the acetamiprid pesticide 10-4 mol • L-1, 100 mV • s-1
Through the comparative representation of the voltamograms (Fig. 11), two significant
differences are identified:
✓ in the absence of pesticide molecules, three maxima of the cathodic current densities
corresponding to the electrochemical reduction of the active chlorine species are
observed;
✓ in the presence of pesticide molecules, an anodic peak is recorded at the value of 1.35
V of the potential of the working electrode attributed to the electrooxidation of the
pesticide molecules on the platinum electrode surface.
UV-Vis spectrophotometric analysis shows a maximum absorption in the Vis range (λ
= 630 nm) for high pesticide concentrations (10-2 mol • L-1) (Fig. 12a).
At lower values of the pesticide concentration (10-4 mol • L-1) a maximum absorption
corresponding to the wavelength of 250 nm is recorded (Fig. 12b).
By recording the UV-Vis spectra of the electrolysed solution, a new absorption
maximum (λ=290 nm) is recorded indicating the presence / formation of a new compound
whose concentration increases over time, this compound may represent a final or intermediate
product of electrochemical degradation. of the pesticide.
0
0.5
1
1.5
200 400 600 800
Abs
orba
nța
lungime de undă / nm
a
0
1
2
3
4
200 300 400 500
Abs
orba
nța
lungime de undă / nm
b
Figure 12. UV-Vis spectra of the solution containing acetamiprid 10-4 mol • L-1, NaCl 10-1 mol • L-1, initially and
18
at different electrolysis times (10 to 10 minutes)
Study of the electrochemical decomposition of emamectin
Figure 13 shows the cyclic voltamograms on the platinum electrode in 10-1 mol • L-1
NaCl solution, both in the absence and in the presence of the emamectin pesticide in the
concentration of 10-5 mol • L-1. At potential values greater than 1.0 V, the two
voltammograms differ significantly. A new maximum of the anodic current density is
recorded (at 1.3 V), so that the charge transfer processes at the metal interface / electrolyte
solution intensify when the pesticide molecules are present in the electrolyte solution (Fig.
5.4)
-60
-30
0
30
60
90
120
-2 -1 0 1 2
i /
mA
·cm
-2
E / V vs. Ag/AgCl,KClsat
a NaCl emamectin_NaCl
-10
-5
0
5
10
-2 -1 0 1 2
i /
mA
·cm
-2
E / V vs. Ag/AgCl,KClsat
b NaCl emamectin_NaCl
Figure 13.. Cyclic voltammograms recorded on a platinum electrode in 10-1 mol NaCl solution • L-1, in the
absence and presence of 10-5 mol emamectin • L-1, 100 mV • s-1
At both negative and small positive values of the potential of the working electrode, it
is observed that the current densities of the voltammogram recorded in the presence of
pesticide molecules are lower than those corresponding to the supporting electrolyte, due to
the strong adsorption of the pesticide molecules on the electrode surface.
The emamectin molecules are photolytic active in the UV domain, exhibiting a
maximum absorption at the wavelength of 228 nm (Fig. 14).
0
1
2
3
200 300 400 500
abso
rban
ța
lungime de undă / nm Figura 14. UV-Vis spectra of emamectin in 10-1 mol NaCl solution • L-1 at different times from the beginning of
the electrolysis process (every 2 minutes)
UV-Vis spectra of the electrolyte solution containing 10-5 mol • L-1 and 10-1 mol NaCl • L-1
recorded at different electrolysis times (Fig. 14.) indicate a decrease in the corresponding
absorbance values of emamectin, in while a new absorption maximum is recorded at the
wavelength value λ = 290 nm. This maximum absorption, recorded at the wavelength of 290
nm, is attributed to the formation of an intermediate compound of the degradation of the
emamectin molecule.
19
Electrochemical degradation of imidacloprid
Figure 15 shows the cyclic voltamograms obtained on the platinum electrode in 10-1 mol • L-1
NaCl solution, both in the absence and in the presence of the imidacloprid at a concentration
of 10-4 mol • L-1. The imidacloprid molecules exhibit an electrochemical behavior similar to
the two pesticides studied previously (acetamiprid and emamectin respectively). A new peak
of the anodic current densities is recorded (Fig. 15.a) at a potential of the working electrode of
approximately 1.5 V. Ag / AgCl, being associated with the electrochemical oxidation of
pesticide molecules.
-60
-30
0
30
60
90
120
-2 -1 0 1 2
i /
mA
·cm
-2
E / V vs. Ag/AgCl,KClsat
a NaCl imidacloprid_NaCl
-10
-5
0
5
10
-2 -1 0 1 2i
/ m
A·c
m-2
E / V vs. Ag/AgCl,KClsat
b NaCl imidacloprid_NaCl
Figure 15. Cyclic voltammograms of Pt electrode in 10-1 mol NaCl solution • L-1, in the absence and presence of
imidacloprid 10-4 mol • L-1 (a), detail of the area of small current densities (b) 100 mV • s-1
The imidacloprid molecules are active in the UV domain and are characterized by a maximum
absorption at the wavelength value of 270 nm. Figure 16 shows the UV-Vis spectra recorded
at different time periods from the beginning of the electrolysis process of the electrolyte
solution containing 10-1 mol NaCl • L-1 and imidacloprid 10-4 mol • L-1 indicating an increase
of the corresponding absorbance values wavelength λ = 270 nm.
0
2
4
6
200 300 400 500
abso
rban
ța
lungime de undă / nm Figure 16. UV-Vis spectra of the solution containing 10-1 mol NaCl • L-1 and imidacloprid 10-4 mol • L-1, at
different periods of electrolysis (from 5 to 5 minutes)
Study of the electrochemical and thermal behavior of propineb Figure 17 shows the cyclic voltammograms of the platinum electrode in 10-1 mol NaCl
solution • L-1 in the absence and presence of propineb 5 • 10-4 mol • L-1.
Current densities corresponding to voltamograms recorded in the presence of pesticide
molecules have lower values than those corresponding to the supporting electrolyte, which
shows that the charge transfer processes take place by the initial adsorption of pesticide
molecules on the electrode surface. By performing a detail of the cyclic voltammograms at
low values of the current densities (b), a new maximum of the anodic current densities
20
attributed with the electrooxidation of the pesticide molecules is easier to identify. This
process is also demonstrated by recording UV-Vis spectrophotograms.
-50
-20
10
40
70
-2 -1 0 1 2
i / m
A·c
m-2
E / V vs. Ag/AgCl,KClsat
a NaCl propineb_NaCl
-10
-5
0
5
10
-2 -1 0 1 2
i /
mA
·cm
-2
E / V vs. Ag/AgCl,KClsat
b NaCl propineb_NaCl
Figure 17. Cyclic voltammograms recorded on Pt electrode in 10-1 mol NaCl solution • L-1, in the absence and
presence of propineb 5 • 10-4 mol • L-1, 100 mV • s-1
Figure 18 shows the UV-Vis spectrum of the 10-1 mol • L-1 NaCl solution containing
propineb 5 • 10-4 mol • L-1, at different times from the beginning of the electrolysis process;
0 minutes and after 20 and 40 minutes respectively after the beginning of the electrolysis
process.
0
1
2
3
200 300 400 500
abso
rban
ța
lungime de undă / nm Figur3 18. UV-Vis spectra of the solution containing 10-1 mol NaCl • L-1 and propineb 5 • 10-4 mol • L-1, at
different periods of electrolysis (0, 20, 40 min.)
According to Figure 18, it can be concluded that after 40 minutes from the beginning
of electrolysis, the electrochemical degradation of propineb is complete.
An important feature of the electrochemical degradation of propineb, as opposed to the
behavior of the other three pesticides studied, is that propineb does not form other
intermediate degradation products.
General conclusions
1. Electrochemical processes of oxidative degradation of organic compounds are
increasingly used in the removal of organic pollutants from wastewater, pollutants
from different branches of industry or pollutants discharged into domestic or
municipal wastewater.
2. The identification of the optimum conditions for electrodegradation of an organic
pollutant is a subject of much scientific research lately and aims: (1) to obtain the
21
highest degree of degradation (ideally 100%); (2) the use of a current density as low as
possible in order to obtain a low cost; (3) the possibility of implementation at the
macro level; (4) the replacement of a conventional method with an alternative
electrochemical method due to the ability to transform a certain organic pollutant into
non-toxic or inorganic degradation intermediates such as mineral acids, carbon dioxide
and water; (5) the elaboration of electro-disinfection systems and their use in
continuous flow; (6) the study of the experimental conditions of temperature, pH,
composition of the electrolyte solution, in order to generate species with very high
reactivity and in sufficient quantity to facilitate the electrochemical degradation of the
organic pollutants; (7) identification of electrodes with superior electrocatalytic
properties capable of conducting the electrooxidation processes by direct mechanisms
to non-toxic products or with very low toxicity.
3. The general objective of the thesis - the study of the stability of polluting organic
compounds in the category of medicines, food dyes and pesticides - was accomplished
by carrying out activities regarding the identification of the electrochemical behavior
of two drugs (vitamin A and 5-fluorouracil), two dyes in the category of food additives
( Chocolate Brown HT and tartrazine) and 4 pesticides (acetamiprid, emamectin,
imidacloprid and propineb).
4. The second general objective of the thesis regarding the elaboration of mechanisms of
decomposition of pollutants by correlating the results obtained experimentally, was
achieved by proposing the mechanism of electrochemical degradation of vitamin A
(retinyl palmitate) on platinum electrodes, elaboration of the mechanism for
electrodegradation of the 5-fluorouracil cytostatic drug on titanium electrodes and the
elaboration of the mechanical degradation of the Chocolate Brown HT food additive.
5. The first specific objective was achieved by studying the electrochemical behavior of
vitamin A in the form of retinyl palmitate in aqueous solutions on platinum electrodes.
The research studies were conducted in the presence of two different support
electrolytes, namely nitrate and sodium chloride, in the absence and respectively in the
presence of silver nanoparticles. Investigation of the electrochemical behavior of
vitamin A using cyclic voltammetry and UV-Vis spectrophotometry led to the
conclusion that in the presence of nitrogen anions the interactions are much weaker as
opposed to the case where the electrolyte solution contains chloride anions and silver
nanoparticles. Cyclic voltammograms showed different forms in hydroalcoholic
solutions containing vitamin A and vitamin A / nAg in the presence of nitrate ions
compared to those recorded in the presence of chloride anions due to specific
22
interactions with the silver nanoparticles depending on the type of the anion. Thus, the
presence of the nitrate anion mainly leads to the electrochemical interaction as
compared to the presence of the chloride anion which favors the chemical interaction.
Based on the results obtained by cyclic voltammetry, in the presence of nitrate ions,
the mechanism of electrochemical decomposition of vitamin A. has been proposed.
6. The second specific objective was achieved by studying the electrochemical stability
of the anti-tumor drug 5-fluorouracil. The shape of the cyclic voltamograms of the
titanium electrode was modified then the electrolyte solution, represented by the 0.9%
saline solution, contained the drug molecules, the values of anodic current densities
had lower values than those recorded in the electrolyte saline solution support, and the
corresponding passivity interval was higher. The electrocatalytic properties of the
titanium made possible the participation of 5FU molecules in the electrode processes
at the electrode / electrolyte interface.
7. The study of the electrochemical stability of the cytostatic 5-fluorouracil allowed the
elaboration of the mechanism of electrochemical degradation of the drug molecules
contributing to the fulfillment of the second specific objective of the thesis.
8. Organic pollutants commonly encountered are drugs, dyes and pesticides with
complex structures, are obtained by chemical synthesis and water soluble, have high
resistance to the action of oxidizing agents, and many of them are not biodegradable.
9. The specific objective represented by the study of the stability of the dyes such as
Chocolate Brown HT and tartrazine was achieved through an extensive research on
the electrochemical and thermal behavior. Kinetic studies of electrochemical
degradation were also performed.
10. The thermal behavior of the food additive Chocolate Brown HT (E155) was studied
based on thermogravimetry (TG) and differential scanning calorimetry (DSC) methods
using Diamond thermal analyzer, Perkin Elmer.
11. Studies on the melting and pyrolysis behavior of the food additive of color E155
observed by TG / DTG analysis have indicated changes in its composition through
several stages of mass reduction. At the end of the experiment, a residue of 33% was
observed. The thermal decomposition of E155 examined by DSC analysis in an inert
atmosphere was also used to study its stability. This analysis accurately indicates
temperatures of use of the dye in the food industry or in domestic use.
12. The electrochemical behavior of Brown HT dye (E155) was studied in the presence of
different halogenated anions. The experimental results obtained by cyclic voltammetry
were corroborated with the data obtained by electrolysis at constant current density;
23
thus it was observed that the degree of electrochemical degradation of the BHT
molecule has the highest value in the presence of bromide anions and the lowest value
in the presence of fluoride ions.
13. From the kinetic point of view, the degradation processes proceed according to simple
kinetic models of zero or first order, without there being a similarity in terms of the
electrochemical behavior.
14. Within the same specific objective was studied the decontamination of simulated
waters polluted with chemical dyes of azo dyes such as tartrazine.
15. This activity was achieved by applying electrochemical methods, such as direct and
indirect electrochemical degradation from aqueous solutions, in the presence of the
supporting electrolytes represented by sodium sulfate and sodium chloride.
16. The effect of the supporting electrolyte on the degree of electrochemical degradation
of tartrazine has been studied by electrolysis at constant current density in association
with UV-Vis spectrophotometry. In the presence of sulphate anions, the degree of
electrochemical degradation reaches a value of 37% at 60 minutes of electrolysis,
while in the presence of chloride anions, the degree of degradation reaches the
maximum value of 100% in only 2 minutes.
17. The experimental results indicate a total electrochemical degradation of the tartrazine
molecules in the sodium chloride solution, whereas in the sodium sulfate solution only
partial electrochemical degradation takes place.
18. Four commonly used pesticides such as acetamiprid, emamectin, imidacloprid and
propineb were studied to optimize electrochemical methods for their degradation from
contaminated simulated waters. The results obtained by cyclic voltammetry confirm
that their molecules are active in the potential range used having anodic oxidation
maxima attributed to the electrooxidation of pesticides.
19. Spectrophotometric analysis of electrolysed solutions at constant current density
shows that three of the studied pesticides (acetampirid, emamectin and imidacloprid)
form new absorption maxima attributed to the appearance of intermediate degradation
compounds. In the case of propineb, there is a classic decrease in absorbance,
indicating that it is degraded electrochemically without forming intermediate products.
20. TG / DTG / DSC thermal analysis shows that all compounds are degraded
inconsecutive steps at specific temperature ranges.
24
Bibliography
1. C. Comninellis, Electrocatalysis in the electrochemical conversion/combustion of organic pollutants for
waste water treatment, Electrochim. Acta, 39 (1994) 1857-1862.
2. C. Comninellis, A. De Battisti, Electrocatalysis in anodic oxidation of organics with simultaneous
oxygen evolution, J. Chim. Phys., 93 (1996) 673-679.
3. O. Simond, V. Schaller, C. Comninellis, Theoretical model for the anodic oxidation of organics on
metal oxide electrodes, Electrochim. Acta, 42 (1997) 2009-2012.
4. G. Foti, D. Gandini, C. Comninellis, A. Perret, W. Haenni, Oxidation of organics by intermediates of
water discharge on IrO2 and synthetic diamond anodes, Electrochem. Solid State Lett., 2 (1999) 228-
230.
5. E. Brillas, E. Mur, J. Casado, Iron(II) catalysis of the mineralization of aniline using a carbon-PTFE
O2-fed cathode, J. Electrochem. Soc., 143 (1996) L49-L53.
6. J. D. Rodgers, W. Jedral, H. J. Bunce, Electrochemical oxidation of chlorinated phenols, Environ. Sci.
Technol., 33 (1999) 1453-1457.
7. M. Panizza, G. Cerisola, Electrochemical oxidation as final treatment of synthetic tannery wastewater,
Environ. Sci. Technol., 38 (2004) 5470-5475.
8. X.-y. Li, Y.-h. Cui, Y.-j. Feng, Z.-m. Xie, J.-D. Gu, Reaction pathways and mechanisms of the
electrochemical degradation of phenol on different electrodes, Water Res., 39 (2005) 1972-1981.
9. C. A. Martinez-Huitle, M. A. Quiroz, C. Comninellis, S. Ferro, A. De Battisti, Electrochemical
incineration of chloranilic acid using Ti=IrO2, Pb=PbO2 and Si/BDD electrodes, Electrochim. Acta, 50
(2004) 949-956.
10. A. M. Polcaro, A. Vacca, M. Mascia, S. Palmas, Oxidation at boron doped diamond electrodes: An
effective method to mineralise triazines, Electrochim. Acta, 50 (2005) 1841-1847.
11. M. E. H. Bergmann, About the chlorine dioxide formation during electrochemical drinking water
disinfection, GWF Wasser Abwasser, 146 (2005) 126-133.
12. H. Bergmann, J. Rollin, C. Czichos, D. Roemer, Perchlorate analysis in drinking water electrolysis-a
new application for Ion Chromatography, Labo, (2007) 26-28.
13. K. Bouzek, H. Bergmann, Paidar, Nitrate removal from drinking and process water, In ALPHA
Informationsgesellschaft GmbH (ed.) Handbuch Umweltwissenschaften, Ausgabe 2003/2004,
Lampertheim, (2003) 81-89.
14. G. Le Truong, J. De Laat, B. Legube, Effect of chloride and sulfate on the rate of oxidation of ferrous
ion by H2O2, Water Res., 38 (2004) 2384-2394.
15. P. K. Brahman, R. A. Dar, K. S. Pitre, Adsorptive stripping voltammetric study of vitamin B1 at multi-
walled carbon nanotube paste electrode, Arab. J. Chem., 9 (2016) S1889-S1896.
16. A. Samide, B. Tutunaru, Interactions between Vitamin C and nanocolloidal silver particles studied by
cyclic voltammetry and UV-Vis spectrophotometry, Electroanal., 29 (2017) 1-10.
17. A. Masek, E. Chrzescijanska, M. Zaborski, Voltammetric and FTIR spectroscopic studies of the
oxidation of retinyl propionate at Pt electrode in non-aqueous media, Int. J. Electrochem. Sci., 9 (2014)
6809 – 6820.
18. X. Lv, J. Zhao, X. Dong, H. Tian, S. Qi, Y. Jiang, Y. Ping, Electrochemical determination of Vitamin A
based on a novel nanoalloy modified carbon paste electrode, Int. J. Electrochem. Sci., 12 (2017) 8457-
8466.
19. A. A. J. Torriero, C. E. Tonn, L. Sereno, J. Raba, Electrooxidation mechanism of non-steroidal anti-
inflammatory drug piroxicam at glassy carbon electrode, J. Electroanal. Chem., 588 (2006) 218-225.
25
20. S. W. da Silva, E. M. O. Navarro, M. A. S. Rodrigues, A. M. Bernardes, V. Pérez-Herranz, Using p-
Si/BDD anode for the electrochemical oxidation of norfloxacin, J. Electroanal. Chem., 832 (2019) 112-
120.
21. J. F. Carneiro, J. M. Aquino, A. J. Silva, J. C. Barreiro, Q. B. Cass, R. C. Rocha-Filho, The effect of the
supporting electrolyte on the electrooxidation of enrofloxacin using a flow cell with a BDD anode:
Kinetics and followup of oxidation intermediates and antimicrobial activity, Chemosphere, 206 (2018)
674-681.
22. S. C. B. Oliveira, C. H. S. Mendes, F. F. S. Filho, N. L. Queiroz, J. A. M. Nascimento, V. B.
Nascimento, Electrochemical oxidation mechanism of procarbazine at glassy carbon electrode, J.
Electroanal. Chem., 746 (2015) 51-56.
23. E. E. S. Bruzaca, I. C. Lopes, E. H. C. Silva, P. A. V. Carvalho, A. A. Tanaka, Electrochemical
oxidation of the antitumor antibiotic mitomycin C and in situ evaluation of its interaction with DNA
using a DNA-electrochemical biosensor, Microchem. J., 133 (2017) 81-89.
24. J. Soleymani, M. Hasanzadehb, N. Shadjou, M. K. Jafari, J. V. Gharamaleki, M. Yadollahi, A. Jouyban,
A new kinetic–mechanistic approach to elucidate electrooxidation of doxorubicin hydrochloride in
unprocessed human fluids using magnetic graphene based nanocomposite modified glassy carbon
electrode, Mater. Sci. Eng. C-Mater. Biol. Appl., 61 (2016) 638-650.
25. T. Gul, R. Bischoff, H. P. Permentier, Optimization of reaction parameters for the electrochemical
oxidation of lidocaine with a Design of Experiments approach, Electrochim. Acta, 171 (2015) 23-28.
26. C. Salazar, N. Contreras, H. D. Mansilla, J. Yánez, R. Salazar, Electrochemical degradation of the
antihypertensive losartan inaqueous medium by electro-oxidation with boron-doped diamond electrode,
J. Hazard. Mater., 319 (2016) 84-92.
27. C.-H. Hung, C. Yuan, M.-H. Wu, Y.-C. Chang, Electrochemical degradation of ibuprofen-contaminated
soils over Fe/Al oxidation electrodes, Sci. Total Environ., 640–641 (2018) 1205-1213.
28. M. S. E. Houache, E. Cossar, S. Ntais, E. A. Baranova, Electrochemical modification of nickel surfaces
for efficient glycerol electrooxidation, J Power Sources, 375 (2018) 310-319.
29. P. Kucerova, J. Skopalova, L. Kucera, J. Hrbác, K. Lemr, Electrochemical oxidation of fesoterodine
and identification of its oxidation products using liquid chromatography and mass spectrometry,
Electrochim. Acta, 159 (2015) 131-139.
30. S. Periyasamy, M. Muthuchamy, Electrochemical oxidation of paracetamol in water by graphite anode:
Effect of pH, electrolyte concentration and current density, JECE, 6 (2018) 7358-7367.
31. E. Wudarska, E. Chrzescijanska, E. Kusmierek, J. Rynkowski, Voltammetric studies of acetylsalicylic
acid electrooxidation at platinum electrode, Electrochim. Acta, 93 (2013) 189-194.
32. G. F. Pereiraa, P. B. Deroco, T. A. Silva, H. S. Ferreira, O. Fatibello-Filho, K. I. B. Eguiluz, G. R.
Salazar-Banda, Study of electrooxidation and enhanced voltammetric determination of β-blocker
pindolol using a boron-doped diamond electrode, Diam. Relat. Mater., 82 (2018) 109-114.
33. E. M. P. J. Garrido, J. M. P. J. Garrido, N. Milhazes, F. Borges, A. M. Oliveira-Brett, Electrochemical
oxidation of amphetamine-like drugs and application to electroanalysis of ecstasy in human serum,
Bioelectrochemistry, 79 (2010) 77-83.
34. E. Brillas, C. A. Martínez-Huitle, Decontamination of wastewaters containing synthetic organic dyes by
electrochemical methods. An updated review, Appl. Catal. B: Environ., 166-167 (2015) 603-643.
35. T. Rafaïdeen, S. Baranton, C. Coutanceau, Highly efficient and selective electrooxidation of glucose
and xylose in alkaline medium at carbon supported alloyed PdAu nanocatalysts, Appl. Catal. B:
Environ., 243 (2019) 641-656.
36. J. H. Q. Lee, S. J. L. Lauw, R. D. Webster, The Electrochemical Study of Vanillin in Acetonitrile,
Electrochim. Acta, 211 (2016) 533-544.
37. R. Rekik, M. Hamza, M. Jaziri, R. Abdelhedi, Electrochemical oxidation of vanillic acid by electro-
Fenton process: Toward a novel route of protocatechuic acid electrosynthesis, Arab. J. Chem., (2017)
https://doi.org/10.1016/j.arabjc.2017.05.001 .
38. M. A. N. Manaia, V. C. Diculescu, E. de Souza Gil, A. M. Oliveira-Brett, Guaicolic spices curcumin
and capsaicin electrochemical oxidation behavior at a glassy carbon electrode, J. Electroanal. Chem.,
682 (2012) 83-89.
39. A. Masek, E. Chrzescijanska, M. Zaborski, Electrooxidation of morin hydrate at a Pt electrode studied
by cyclic voltammetry, Food Chem., 148 (2014) 18-23.
40. N. P. Shetti, D. S. Nayak, S. J. Malode, Electrochemical behavior of azo food dye at nanoclay modified
carbon electrode-a nanomolar determination, Vacuum, 155 (2018) 524-530.
41. G. Yildiza, Z. Aydogmus, M. E. Cinar, F. Senkal, T. Ozturk, Electrochemical oxidation mechanism of
eugenol on graphene modified carbon paste electrode and its analytical application to pharmaceutical
analysis, Talanta, 173 (2017) 1-8.
42. N. P. Shettia, D. S. Nayak, G. T. Kuchinad, Electrochemical oxidation of erythrosine at TiO2
nanoparticles modified gold electrode - An environmental application, JECE, 5 (2017) 2083-2089.
26
43. A. Thiam, E. Brillas, J. A. Garrido, R. M. Rodríguez, I. Sirés, Routes for the electrochemical
degradation of the artificial food azo-colour Ponceau 4R by advanced oxidation processes, Appl. Catal.
B: Environ., 180 (2016) 227-236.
44. A. Thiam, I. Sires, E. Brillas, Treatment of a mixture of food color additives (E122, E124 and E129) in
different water matrices by UVA and solar photoelectro-Fenton, Water Res., 81 (2015) 178-187.
45. W. R. P. Barros, P. C. Franco, J. R. Steter, R. S. Rocha, M. R. V. Lanza, Electro-Fenton degradation of
the food dye amaranth using a gas diffusion electrode modified with cobalt (II) phthalocyanine, J.
Electroanal. Chem., 722-723 (2014) 46-53.
46. L. Fan, Y. Zhou, W. Yang, G. Chen, F. Yang, Electrochemical degradation of Amaranth aqueous
solution on ACF, J. Hazard. Mater., B137 (2006) 1182-1188.
47. C. Chen, E. Nurhayati, Y. Juang, C. Huang, Electrochemical decolorization of dye wastewater by
surface-activated boron-doped nanocrystalline diamond electrode, J. Environ. Sci., 45 (2016) 100-107.
48. P. Aravind, V. Subramanyan, S. Ferro, R. Gopalakrishnan, Eco-friendly and facile integrated
biological-cum-photo assisted electrooxidation process for degradation of textile wastewater, Water
Res., 93 (2016) 230-241.
49. C, Indermuhle, M, J. M. de Vidales, C. Sáez, J. Robles, P. Cañizares, J. F. García-Reyes, A. Molina-
Díaz, C. Comninellis, M. A. Rodrigo, Degradation of caffeine by conductive diamond electrochemical
oxidation, Chemosphere, 93 (2013) 1720-1725.
50. M. Hvězdová, P. Kosubová, M. Košíková, K. E. Scherr, Z. Šimek, L. Brodský, M. Šudoma, L.
Škulcová, M. Sáňka, M. Svobodová, L. Krkošková, J. Vašíčková, N. Neuwirthová, L. Bielská, J.
Hofman, Currently and recently used pesticides in Central European arable soils, Sci. Total Environ.,
613–614 (2018) 361-370.
51. L. Jing, B. Chen, D. Wen, J. Zheng, B. Zhang, Pilot-scale treatment of atrazine production wastewater
by UV/O3/ultrasound: Factor effects and system optimization, J. Environ. Manage., 203 (2017) 182-
190.
52. V. Lizano-Fallas, M. Masís-Mora, D. Espinoza-Villalobos, M. Lizano-Brenes, C. E. Rodríguez-
Rodríguez, Removal of pesticides and ecotoxicological changes during the simultaneous treatment of
triazines and chlorpyrifos in biomixtures, Chemosphere, 182 (2017) 106-113.
53. S. Y. Kim, H. G. Ahn, P. J. Ha, U. T. Lim, J.-H. Lee, Toxicities of 26 pesticides against 10 biological
control species, J. Asia-Pac. Entomol., 21 (2018) 1-8.
54. R. Sinha, M. Ganesana, S. Andreescu, L. Stanciu, AChE biosensor based on zinc oxide sol–gel for the
detection of pesticides, Anal. Chim. Acta, 661 (2010) 195–199.
55. D. Dua, X. Huang, J. Cai, A. Zhang, Amperometric detection of triazophos pesticide using
acetylcholinesterase biosensor based on multiwall carbon nanotube–chitosan matrix, Sensor. Actuat. B-
Chem., 127 (2007) 531-535.
56. I. Ion, A. C. Ion, Determination of chlorpyriphos in broccoli using a voltammetric acetylcholinesterase
sensor based on carbon nanostructure–chitosan composite material, Mater. Sci. Eng. C-Mater. Biol.
Appl., 32 (2012) 1001-1004.
57. L. F. Sgobbi, S. A. S. Machado, Functionalized polyacrylamide as an acetylcholinesterase-inspired
biomimetic device for electrochemical sensing of organophosphorus pesticides, Biosens. Bioelectron.,
100 (2018) 290-297.
58. I. Cesarino, F. C. Moraes, M. R. V. Lanza, S. A. S. Machado, Electrochemical detection of carbamate
pesticides in fruit and vegetables with a biosensor based on acetylcholinesterase immobilised on a
composite of polyaniline–carbon nanotubes, Food Chem., 135 (2012) 873-879.
59. K. Sipa, M. Brycht, A. Leniart, P. Urbaniak, A. Nosal-Wiercińska, B. Pałecz, S. Skrzypek, β–
Cyclodextrins incorporated multi-walled carbon nanotubes modified electrode for the voltammetric
determination of the pesticide dichlorophen, Talanta, 176 (2018) 625-634.
60. T. Maulidiyah, A. T. Azis, D. Nurwahidah, M. Wibowo, Nurdin, Photoelectrocatalyst of Fe co-doped
N-TiO2/Ti nanotubes: Pesticide degradation of thiamethoxam under UV–visible lights, Environmental
Nanotechnology, Monitoring & Management, 8 (2017) 103-111.
61. G. Liu, Y. Lin, Electrochemical stripping analysis of organophosphate pesticides and nerve agents,
Electrochem. Commun., 7 (2005) 339-343.
62. O. Surucu, G. Bolat, S. Abaci, Electrochemical behavior and voltammetric detection of fenitrothion
based on a pencil graphite electrode modified with reduced graphene oxide (RGO)/poly(E)-1-(4-((4-
(phenylamino)phenyl)diazenyl)phenyl)ethanone (DPA) composite film, Talanta, 168 (2017) 113-120.
63. M. Guler, V. Turkoglu, Z. Basi, Determination of malation, methidathion, and chlorpyrifos ethyl
pesticides using acetylcholinesterase biosensor based on Nafion/Ag@rGO-NH2 nanocomposites,
Electrochim. Acta, 240 (2017) 129-135.
64. A. Jirasirichote, E. Punrat, A. Suea-Ngam, O. Chailapakul, S. Chuanuwatanakul, Voltammetric
detection of carbofuran determination using screen-printed carbon electrodes modified with gold
nanoparticles and graphene oxide, Talanta, 175 (2017) 331-337.
65. O. Kukurina, Z. Elemesova, A. Syskina, Mineralization of organophosphorous pesticides by electro-
generated oxidants, Procedia Chem., 10 ( 2014 ) 209-216.
27
66. Y. Aimer, O. Benali, K. G. Serrano, Study of the degradation of an organophosphorus pesticide using
electrogenerated hydroxyl radicals or heat-activated persulfate, Sep. Purif. Technol., 208 (2019) 27-33.
67. J. Muff, C. D. Andersen, R. Erichsen, E. G. Soegaard, Electrochemical treatment of drainage water
from toxic dump of pesticides and degradation products, Electrochim. Acta, 54 (2009) 2062-2068.
68. C. R. Landeros, C. E. Barrera Díaz, A. A. Cháves, G. R. Morales, Evaluation of a coupled system of
electro-oxidation and ozonation to remove the pesticide Thiodan 35 CE (endosulfan) in aqueous
solution, Fuel, 198 (2017) 91-98.
69. J. D. Lovic, D. Z. Mijin, M. B. Jovanovic, O. S. Glavaski, T. M. Zeremski, S. D. Petrovic, M. L. A.
Ivic, An investigation of tebuconazole degradation using a gold electrode, C. R. Chimie, 19 (2016) 639-
645.
70. F. L. Souza, M. R. V. Lanza, J. Llanos, C. Saez, M. A. Rodrigo, P. Canizares, A wind-powered BDD
electrochemical oxidation process for the removal of herbicides, J. Environ. Manage., 158 (2015) 36-
39.
71. T. D. Lazarevic´-Pašti, A. M. Bondzic, I. A. Pašti, S. V. Mentus, V. M. Vasic, Electrochemical
oxidation of diazinon in aqueous solutions via electrogenerated halogens – Diazinon fate and
implications for its detection, J. Electroanal. Chem., 692 (2013) 40-45.
72. D. W. Miwa, G. R. P. Malpass, S. A. S. Machado, A. J. Motheo, Electrochemical degradation of
carbaryl on oxide electrodes, Water Res., 40 (2006) 3281-3289.
73. T. Ramya, M. Anbazhagi, M. Muthukumar, Electrochemical oxidation of fipronil contaminated
wastewater by RuO2/IrO2/TaO2 coated titanium anodes and sorbent nano hydroxyapatite, Mater.
Today: Proceedings, 3 (2016) 2509-2517.
74. F. Zaviska, P. Drogui, J.-F. Blais, G. Mercier, P. Lafrance, Experimental design methodology applied to
electrochemical oxidation of the herbicide atrazine using Ti/IrO2 and Ti/SnO2 circular anode
electrodes, J. Hazard. Mater., 185 (2011) 1499-1507.
75. Y. Samet, L. Agengui, R. Abdelhédi, Anodic oxidation of chlorpyrifos in aqueous solution at lead
dioxide electrodes, J. Electroanal. Chem., 650 (2010) 152-158.
76. Q. Ren, C. Yin, Z. Chen, M. Cheng, Y. Ren, X. Xie, Y. Li, X. Zhao, L. Xu, H. Yang, W. Li, Efficient
sonoelectrochemical decomposition of chlorpyrifos in aqueous solution, Microchem. J., 145 (2019)
146-153.
77. F. de Assis Avelino de Figueredo-Sobrinho, F. W. de Souza Lucas, T. P. Fill, E. Rodrigues-Filho, L. H.
Mascaro, P. N. da Silva Casciano, P. de Lima-Neto, A. N. Correia, Insights into electrodegradation
mechanism of tebuconazole pesticide on Bi-doped PbO2 electrodes, Electrochim. Acta, 154 (2015)
278-286.
78. C. M. Domingueza, N. Oturan, A. Romero, A. Santos, M. A. Oturan, Optimization of electro-Fenton
process for effective degradation of organochlorine pesticide lindane, Catal. Today, 313 (2018) 196-
202.
79. C. M. Dominguez, N. Oturan, A. Romero, A. Santos, M. A. Oturan, Removal of lindane wastes by
advanced electrochemical oxidation, Chemosphere, 202 (2018) 400-409.
80. S. Liu, T. Cui, A. Xu, W. Han, J. Li, X. Sun, J. Shen, L. Wang, Electrochemical treatment of flutriafol
wastewater using a novel 3D macroporous PbO2 filter: Operating parameters, mechanism and toxicity
assessment, J. Hazard. Mater., 358 (2018) 187-197.
81. G. F. Pereiraa, B. F. Silva, R. V. Oliveira, D. A. C. Coledam, J. M. Aquino, R. C. Rocha-Filho, N.
Bocchi, S. R. Biaggio, Comparative electrochemical degradation of the herbicide tebuthiuron using a
flow cell with a boron-doped diamond anode and identifying degradation intermediates, Electrochim.
Acta, 247 (2017) 860-870.
82. S. Aquino Neto, A.R. de Andrade, Electrooxidation of glyphosate herbicide at different DSA®
compositions: pH, concentration and supporting electrolyte effect, Electrochim. Acta 54 (2009) 2039-
2045.
83. K. Barbari, R. Delimi, Z. Benredjem, S. Saaidia, A. Djemel, T. Chouchane, N. Oturan, M. A. Oturan,
Photocatalytically-assisted electrooxidation of herbicide fenuron using a new bifunctional electrode
PbO2/SnO2-Sb2O3/Ti//Ti/TiO2, Chemosphere, 203 (2018) 1-10.
84. H. Rubí-Juárez, S. Cotillas, C. Sáez, P. Cañizares, C. Barrera-Díaz, M. A. Rodrigo, Use of conductive
diamond photo-electrochemical oxidation for the removal of pesticide glyphosate, Sep. Purif. Technol.,
167 (2016) 127-135.
85. I. Baldea, Cinetica Chimicǎ și mecanisme de Reacție, presa universitarǎ Clujana, 2002.
86. P. W. Atkins, Tratat de Chimie Fizicǎ, Ed. Tehnica, Bucuresti, 1996.
87. I. A. Schneider, Cinetică Chimică, Editura Didactică și Pedagogică, 1974.
88. L. Odochian, M. Dumitras, Teoria cineticǎ și mecanismul reacțiilor ȋn lanț, Ed. Matrixrom, 2003.
89. A. Birzu, M. Dumitras, Cinetică chimică. Capitol special, Ed. Matrixrom ,2010
90. Z. Frontistis, D. Mantzavinos, S. Meriç, Degradation of antibiotic ampicillin on boron-doped diamond
anode using the combined electrochemical oxidation - Sodium persulfate process, J. Environ. Manage.,
223 (2018) 878-887.
28
91. B. G. Padilla-Robles, A. Alonso, S. A. Martínez-Delgadillo, M. González-Brambila, U. J. Jaúregui-
Haza, J. Ramírez-Muñoz, Electrochemical degradation of amoxicillin in aqueous media, Chem. Eng.
Process., 94 (2015) 93-98.
92. C. Wang, L. Yin, Z. Xu, J. Niu, L.-A. Hou, Electrochemical degradation of enrofloxacin by lead
dioxide anode: Kinetics, mechanism and toxicity evaluation, Chem. Eng. J., 326 (2017) 911-920.
93. A. Fabianska, A. Białk-Bielinska, P. Stepnowski, S. Stolte, E. Maria Siedlecka, Electrochemical
degradation of sulfonamides at BDD electrode: Kinetics, reaction pathway and eco-toxicity evaluation,
J. Hazard. Mater., 280 (2014) 579-587.
94. O. Turkay, S. Barısçi, E. Ulusoy, M. G. Seker, A. Dimoglo, Anodic oxidation of anti-cancer drug
Imatinib on different electrodes: Kinetics, transformation by-products and toxicity assessment,
Electrochim. Acta, 263 (2018) 400-408.
95. E. M. Siedlecka, A. Ofiarska, A. F. Borzyszkowska, A. Białk-Bielinska, P. Stepnowski, A. Pieczynska,
Cytostatic drug removal using electrochemical oxidation with BDD electrode: Degradation pathway
and toxicity, Water Res., 144 (2018) 235-245.
96. W. Li, J. Tanumihardja, T. Masuyama, G. Korshin, Examination of the kinetics of degradation of the
antineoplastic drug5-fluorouracil by chlorine and bromine, J. Hazard. Mater., 282 (2015) 125-132.
97. A. Fabianska, A. Ofiarska, A. Fiszka-Borzyszkowska, P. Stepnowski, E. M. Siedlecka,
Electrodegradation of ifosfamide and cyclophosphamide at BDD electrode: Decomposition pathway
and its kinetics, Chem. Eng. J., 276 (2015) 274-282.
98. G. Loos, T. Scheers, K. Van Eyck, A. Van Schepdael, E. Adams, B. Van der Bruggen, D. Cabooter, R.
Dewil, Electrochemical oxidation of key pharmaceuticals using a boron doped diamond electrode, Sep.
Purif. Technol., 195 (2018) 184-191.
99. Z. H. Mussa, F. F. Al-Qaim, M. R. Othman, Md Pauzi Abdullah, Jalifah Latip, Zuriati Zakria, Pseudo
first order kinetics and proposed transformation products pathway for the degradation of diclofenac
using graphite–PVC composite as anode, J. Taiwan Inst. Chem. Eng., 72 (2017) 37-44.
100. Y.-J. Liu, C.-Y. Hu, S.-L. Lo, Direct and indirect electrochemical oxidation of amine-containing
pharmaceuticals using graphite electrodes, J. Hazard. Mater., 366 (2019) 592-605.
101. Y. He, X. Wang, W. Huang, R. Chen, W. Zhang, H. Li, H. Lin, Hydrophobic networked PbO2
electrode for electrochemical oxidation of paracetamol drug and degradation mechanism kinetics,
Chemosphere, 193 (2018) 89-99.
102. E. Hermosillo-Arellano, R. Ocampo-Perez, A. M. Sanchez-Polo, M. Sanchez-Polo, L. M. Flores-Vélez,
E. Mendoza-Mendoza, Role of the radical promoter systems on the degradation of an antipeleptic drug
using HO and SO4 - species, J. Water Process Eng., 27 (2019) 162-170.
103. C. Ridruejo, C. Salazar, P. L. Cabot, F. Centellas, E. Brillas, I. Sirés, Electrochemical oxidation of
anesthetic tetracaine in aqueous medium. Influence of the anode and matrix composition, Chem. Eng.
J., 326 (2017) 811-819.
104. N. M. P. Queiroz, I. Sirés, C. L. P. S. Zanta, J. Tonholo, E. Brillas, Removal of the drug procaine from
acidic aqueous solutions using a flow reactor with a boron-doped diamond anode, Sep. Purif. Technol.,
216 (2019) 65-73.
105. W. Gwala, R. Padmavati, Comparative study of degradation kinetics of ascorbic acid (Vitamin C) in
tray drying, solar drying and open sun drying of pineapple slices, Austin J Nutr. Metab., 2(1) (2015) 1-
5.
106. S. Rahmawati, B. Bundjali, Kinetics of the oxidation of vitamin C, Indo. J. Chem., 12(3) (2012) 291-
296.
107. V. V. Grudic, N. Z. Blagojevic, V. L. Vukasinovic-Pesic, S. R. Brasanac, Kinetics of degradation of
ascorbic acid by cyclic voltammetry method, Chem. Ind. Chem. Eng. Q., 21(2) (2015) 351-357.
108. W. R. P. Barros, J. R. Steter, M. R. V. Lanza, A. C. Tavares, Catalytic activity of Fe3−xCuxO4
(0≤x≤0.25) nanoparticles for the degradation of Amaranth food dye by heterogeneous electro-Fenton
process, Appl. Catal. B: Environ., 180 (2016) 434-441.
109. N. B. Hafaiedh, N. Bellakhal, Electrochemical oxidation of the azo dye Ponceau 4R by electro-Fenton
process, IJERT, 5(6) (2016) 751-756.
110. A. A. El-Zomrawy, Kinetic studies of photoelectrocatalytic degradation of Ponceau 6R dye with
ammonium persulfate, J. Saudi Chem. Soc., 17 (2013) 397-402.
111. A. M. S. Solano, C. A. Martínez-Huitle, S. Garcia-Segura, A. El-Ghenymy, E. Brillas, Application of
electrochemical advanced oxidation processes with a boron-doped diamond anode to degrade acidic
solutions of Reactive Blue 15 (Turqueoise Blue) dye, Electrochim. Acta, 197 (2016) 210-220.
112. Q. Dai, L. Jiang, X. Luo, Electrochemical oxidation of Rhodamine B: Optimization and degradation
mechanism, Int. J. Electrochem. Sci., 12 (2017) 4265-4276.
113. M. Siddique, R. Farooq, Z. M. Khan, Z. Khan, S.F . Shaukat, Enhanced decomposition of reactive blue
19 dye in ultrasound assisted electrochemical reactor, Ultrason. Sonochem., 18 (2011) 190-196.
114. Y. Zhang, Z. Chen, L. Zhou, P. Wu, Y. Zhao, Y. Lai, F. Wang, S. Li, Efficient electrochemical
degradation of tetrabromobisphenol A using MnO2/MWCNT composites modified Ni foam as cathode:
Kinetic analysis, mechanism and degradation pathway, J. Hazard. Mater., 369 (2019) 770-779.
29
115. D. Ghime, P. Ghosh, Decolorization of diazo dye trypan blue by electrochemical oxidation: Kinetics
with a model based on the Fermi’s equation, 2018, https://doi.org/10.1016/j.jece.2018.11.037
116. X. Florenza, S. Garcia-Segura, F. Centellas, E. Brillas, Comparative electrochemical degradation of
salicylic and aminosalicylic acids: Influence of functional groups on decay kinetics and mineralization,
Chemosphere, 154 (2016) 171-178.
117. M. Panizza, G. Cerisola, Electrochemical degradation of gallic acid on a BDD anode, Chemosphere, 77
(2009) 1060-1064.
118. Q. Dai, J. Zhou, X. Meng, D. Feng, C. Wu, J. Chen, Electrochemical oxidation of cinnamic acid with
Mo modified PbO2 electrode: Electrode characterization, kinetics and degradation pathway, Chem.
Eng. J., 289 (2016) 239-246.
119. H. Zazou, N. Oturan, H. Zhang, M. Hamdani, M. A. Oturan, Comparative study of electrochemical
oxidation of herbicide 2,4,5-T: Kinetics, parametric optimization and mineralization pathway, SER, 27
(2017) 15-23.
120. A. Ozcan, Y. Sahin, M. A. Oturan, Complete removal of the insecticide azinphosmethyl from water by
the electro-Fenton method - A kinetic and mechanistic study, Water Res., 47 (2013) 1470-1479.
121. D. R. V. Guelfi, Z. Ye, F. Gozzi, S. César de Oliveira, A. Machulek Junior, E. Brillas, I. Sirés,
Ensuring the overall combustion of herbicide metribuzin by electrochemical advanced oxidation
processes. Study of operation variables, kinetics and degradation routes, Sep. Purif. Technol., 211
(2019) 637-645.
122. A. Dhaouadi, N. Adhoum, Degradation of paraquat herbicide by electrochemical advanced oxidation
methods, J. Electroanal. Chem., 637 (2009) 33-42.
123. C. M. Dominguez, N. Oturan, A. Romero, A. Santos, M. A. Oturan, Optimization of electro-Fenton
process for effective degradation of organochlorine pesticide lindane, Catal. Today, 313 (2018) 196-
202.
124. C. M. Dominguez, N. Oturan, A. Romero, A. Santos, M. A. Oturan, Lindane degradation by
electrooxidation process: Effect of electrode materials on oxidation and mineralization kinetics, Water
Res., 135 (2018) 220-230.
125. M. Errami, R. Salghi, A. Zarrouk, A. Chakir, S. S. Al-Deyab, B. Hammouti, L.Bazzi, H. Zarrok,
Electrochemical combustion of insecticides endosulfan and deltamethrin in aqueous medium using a
boron-doped diamond anode, Int. J. Electrochem. Sci., 7 (2012) 4272-4285.
126. O. ID El Mouden, M. Errami, R. Salghi, A. Zarrouk, M. Assouag, H. Zarrok, S.S. Al-Deyab, B.
Hammouti, Electrochemical degradation of difenoconazole on BDD electrodes, J. Chem. Pharm. Res.,
4(7) (2012) 3437-3445.
127. B. N. Grgur, D. Z. Mijin, A kinetics study of the methomyl electrochemical degradationin the chloride
containing solutions, Appl. Catal. B: Environ., 147 (2014) 429-438.
128. R. Vargas, S. Díaz, L. Viele, O. Núnez, C. Borrás, J. Mostany, B. R. Scharifker, Appl. Catal. B:
Environ., 144 (2014) 107-111.
129. H. Bouya, M. Errami, R. Salghi, Lh. Bazzi, A. Zarrouk, S. S. Al-Deyab, B. Hammouti, L. Bazzi, A.
Chakir, Electrochemical Degradation of Cypermethrin Pesticide on a SnO2 Anode, Int. J. Electrochem.
Sci., 7 (2012) 3453-3465.
130. B. Tutunaru, A. Samide, C. Neamțu, C. Tigae, Spectroelectrochemical studies of interactions between
Vitamin A and nanocolloidal silver, Int. J. Electrochem. Sci., 13 (2018) 5850–5859.
131. B. Tutunaru, C Neamțu, Studiul interacțiilor chimice și electrochimice dintre vitamina A și
nanoparticulele de argint, Annals of the University of Craiova, The Chemistry Series, Simpozionul
Național de Chimie, ed. a IX-a, Contribuții la Creșterea Calității Învățământului și Cercetării în
Domeniul Chimiei, Craiova, 04 noiembrie 2017, p. 50.
132. B. Tutunaru, A. Samide, C. Tigae, C. Spînu, C. Neamțu, Spectroelectrochemical studies of interactions
between Vitamin A and silver nanocolloids, Roumanian International Conference on Chemistry and
Chemical Engineering, http://riccce20.chimie.upb.ro/ (RICCCE), Poiana Brașov, 6-9 septembrie 2017,
România.
133. Q. Xia, J. J. Yin, S. H. Cherng, W. G. Wamer, M. Boudreau, P. C. Howard, P. P. Fu, UVA
photoirradiation of retinyl palmitate-Formation of singlet oxygen and superoxide, and their role in
induction of lipid peroxidation, Toxicol. Lett., 163 (2006) 30-43.
134. P. P. Fu, Q. Xia, J. J. Yin, S. H. Cherng, J. Yan, N. Mei, T. Chen, M. D. Boudreau, P. C. Howard, W.
G. Wamer, Photodecomposition of vitamin A and photobiological implications for the skin, Photochem.
Photobiol., 83 (2007) 409-424.
135. B. Tutunaru, C. Tigae, C. Spînu, I. Prunaru, Spectrophotometry and electrochemistry of Brilliant Blue
FCF in aqueous solution of NaX, Int. J. Electrochem. Sci., 12 (2017) 396-412.
136. G. Ziyatdinova, M. Morozov, H. Budnikov, MWNT-modified electrodes for voltammetric
determination of lipophilic vitamins, J. Solid State Electrochem., 16 (2012) 2441-2447.
137. H. Filik, A. A. Avan, S. Aydar, Simultaneous electrochemical determinationof α-tocopherol and retinol
in micellar media by a poly (2, 2′ - (1,4 phenylenedivinylene) – bis – 8 - hydroxyquinaldine) -
multiwalled carbon nanotube modified electrode, Analyt. Lett., 49 (2016) 1240-1257.
30
138. C. Neamțu, B. Tutunaru, Electrochemical and thermal behavior of 5-fluorouracil antitumor drug,
Annals of the University of Craiova, The Chemistry Series, XLV, 1 (2018) 10-17.
139. A. Yaraghi, O. M. Ozkendir, M. Mirzaei, DFT studies of 5-fluorouracil tautomers on a silicon graphene
nanosheet, Superlattices and Microstruct., 85 (2015) 784-788.
140. M. Mizraei, O. Gulseren, N. Hadipour, DFT explorations of quadrupole coupling constants for planar
5-fluorouracil pairs, Comp. Theor. Chem., 1090 (2016) 67-73.
141. B. Tutunaru, A. Samide, C. Tigae, C. Spînu, C. Neamțu, Electrochemical and thermal stability of
Brown HT food additive, 4th Central and Eastern European Conference on Thermal Analysis and
Calorimetry (CEEC-TAC4), 28-31 August 2017, Chișinău, Republic of Moldova.
142. B. Tutunaru, A. Samide, C. Neamțu, I. Prunaru, Electrochemical and thermal stability of Chocolate
Brown HT food additive, Chem. Ind. Chem. Eng. Q., 2019, 25(1) 89-96.
143. A. Samide, B. Tutunaru, Eurovanillin thermal behaviour and its inhibitory properties on carbon steel
corrosion in weakly acidic environments, J. Therm. Anal. Calorim. 127 (2017) 863-870.
144. A. Samide, B. Tutunaru, Thermal behavior of the chlorophyll extract from a mixture of plants and
seaweed, J. Therm. Anal. Calorim. 127 (2017) 597–604.
145. B. Jankovic, S. Mentus, M. Jankovic, A kinetic study of the thermal decomposition process of
potassium metabisulfite: Estimation of distributed reactivity model, J. Phys. Chem. Solids 69 (2008)
1923-1933.
146. J.C. Halle, K.H. Stern, Vaporization and decomposition of Na2SO4, thermodynamics and kinetics, J.
Phys. Chem. 84 (1980) 1699-1704.
147. B. Tutunaru, C. Tigae, C. Spînu, I. Prunaru, Spectrophotometry and electrochemistry of Brilliant Blue
FCF in aqueous solution of NaX, Int. J. Electrochem. Sci. 12 (2017) 396-412.
148. F. Turak, M. Dinc, O. Dulger, M.U. Ozgur, Four derivative spectrophotometric methods for the
simultaneous determination of carmoisine and Ponceau 4R in drinks and comparison with High
Performance Liquid Chromatography, Int. J. Anal. Chem. (2014) ID 650465, DOI:
10.1155/2014/650465.
149. A.J. Hassan, H.A. Salman, The effect study of using different concentrations of Chocolate Brown dye
(Chocolate Brown HT E155) on some physiological parameters and histological structure of stomach
and intestine on albino rats, AL-Qadisiyha J. Sci. 21 (2016) 1-13.
150. B. Tutunaru, C Neamțu, C. Tigae, A. Dobrițescu, C. Spînu, The electrochemical response of tartrazine
in electrified salted aqueous solution, Annals of the University of Craiova, The Chemistry Series,
Volume XLIV, No. 1 (2017) 84-92.
151. C. Neamțu, Studiul stabilității electrochimice a unor pesticide, Annals of the University of Craiova,
The Chemistry Series, Simpozionul Național de Chimie, ed. a IX-a, Contribuții la Creșterea Calității
Învățământului și Cercetării în Domeniul Chimiei, Craiova, 24 noiembrie 2018, p. 50.
152. C. Neamțu, B. Tutunaru, A. Samide, A. Popescu, Reducing the ecotoxicity of pesticide polluted waters
by electrochemical methods, Rev. Chim. 70 (2019) 1574-1578.
31
Craiova University
Science College
Doctoral School of Science
Department of Chemistry
LIST OF WORKS
Drd. Cristian-Ovidiu Neamţu
Papers published in ISI journals
1. B. Tutunaru, A. Samide, C. Neamțu, C. Tigae, Spectroelectrochemical studies of
interactions between Vitamin A and nanocolloidal silver, International Journal of
Electrochemical Science, 13 (2018) 5850–5859/ FI la publicare: 1,284.
2. B. Tutunaru, A. Samide, C. Neamțu, I. Prunaru, Electrochemical and thermal stability of
Chocolate Brown HT food additive, Chemical Industry & Chemical Engineering
Quarterly, 25 (2019) 25 89-96/ FI la publicare: 0,806.
3. C. Neamțu, B. Tutunaru, A. Samide, A. Popescu, Reducing the ecotoxicity of pesticide
polluted waters by electrochemical methods, Revista de Chimie, 70 (2019) 1574-1578/ FI
la publicare: 1,605.
Hirsch index: 3,695
Papers published in specialized magazines
1. B. Tutunaru, C Neamțu, C. Tigae, A. Dobrițescu, C. Spînu, The electrochemical response
of tartrazine in electrified salted aqueous solution, Annals of the University of Craiova,
The Chemistry Series, Vol. XLIV 1 (2017) 84-92.
2. C. Neamțu, B. Tutunaru, Electrochemical and thermal behavior of 5-fluorouracil
antitumor drug, Annals of the University of Craiova, The Chemistry Series, Vol. XLV, 1
(2018) 10-17.
32
Studies presented at national/international symposiums/conferences
1. B. Tutunaru, A. Samide, C. Tigae, C. Spînu, C. Neamțu, Electrochemical and thermal
stability of Brown HT food additive, 4th Central and Eastern European Conference on
Thermal Analysis and Calorimetry (CEEC-TAC4), 28-31 August (2017) Chișinău,
Republic of Moldova, Rezumat publicat în Book of Abstracts, p.278.
2. B. Tutunaru, A. Samide C. Tigae, C. Spinu, C. Neamtu, Spectroelectrochemical Studies
of Interactions Between Vitamin A and Silver Nanocoloids, 20th Romanian International
Conference on Chemistry and Chemical Engineering Poiana Brasov Romania -
September 6-9, (2017).
3. B. Tutunaru, C.Neamtu, Studiul interactiilor chimice si electrochimice dintre vitamina A
si nanoperticule de Ag, Simpozionul National de Chimie, Craiova, nov. Annals of the
University of Craiova, The Chemistry Series, (2017) S.I. p. 50.
4. C. Neamţu, Studiul stabilitatii electrochimice a unor pesticide. Depoluarea apelor
reziduale, Simpozionul Național de Chimie, ed. a IX‐a, Contribuții la Creșterea Calității
Învățământului și Cercetării în Domeniul Chimiei, Craiova, 24 noiembrie 2018; Rezumat
publicat în Annals of the University of Craiova, The Chemistry Series, (2018) p.50.
27.09.2019 Drd. Cristian-Ovidiu Neamţu
