Youssef Samet | Faculty of Sciences of Sfax (original) (raw)

Papers by Youssef Samet

Research paper thumbnail of Influence of anode material and chlorides in the new-gen solid polymer electrolyte cell for electrochemical oxidation – Optimization of Chloroxylenol degradation with response surface methodology

Journal of Electroanalytical Chemistry

Research paper thumbnail of Full paper / Memoire Improvement of the electrocatalytic activity of platinum in oxidation of aromatic compounds

Research paper thumbnail of Anodic oxidation of chlorpyrifos in aqueous solution at lead dioxide electrodes

Journal of Electroanalytical Chemistry, 2010

Research paper thumbnail of Abdelhédi Fenton and solar photo-Fenton processes for the removal of chlorpyrifos insecticide in wastewater

The degradation of chlorpyrifos in water by Fenton (H2O2/Fe 2+) and solar photo-Fenton (H2O2/Fe 2... more The degradation of chlorpyrifos in water by Fenton (H2O2/Fe 2+) and solar photo-Fenton (H2O2/Fe 2+/solar light) processes was investigated. A laboratory-scale reactor was designed to evaluate and select the optimal oxidation condition. The degrada-tion rate is strongly dependent on pH, temperature, H2O2 dosing rate, and initial concentrations of the insecticide and Fe 2+. The kinetics of organic matter decay was evaluated by means of chemical oxygen demand (COD) measurement. Overall kinetics can be described by a pseudo-second-order rate equation with respect to COD. The optimum conditions were obtained at pH 3, H2O2 dosing rate 120 mg∙min –1, [Fe2+]0 5.0 mM, initial COD 1 330 mg∙ℓ –1 and 35 C for the Fenton process. However, in the solar photo-Fenton process, the degradation rate increased significantly. To achieve 90 % of COD removal, the solar photo-Fenton process needs 50 % less time than that used in the Fenton process which translates to a 50 % gain of H2O2.

Research paper thumbnail of A Study of the Electrochemical Oxidation of Guaiacol

The electrochemical oxidation of guaiacol (2-methoxyphenol) on a treated disk of gold was studied... more The electrochemical oxidation of guaiacol (2-methoxyphenol) on a treated disk of gold was studied by cyclic voltammetry. At low concentration, guaiacol undergoes one irreversible anodic peak . The current of this peak has a diffusional origin. For guaiacol concentrations higher than 4 . 10 -2 mol dm -3 , the voltammogram shows a post-peak. The effect of experimental data on the ratio of these two peaks was examined. The proposed mechanism is based on the hypothesis of two-electron oxidation of the guaiacol molecule, involving the intermediary of three phenoxonium cation mesomers. Quantitative importance of these cations is governed by their relative stability. Hydrolysis of these phenoxonium cations would lead to the formation of catechol, methoxyhydroquinone and 3-methoxycatechol. The preliminary results show that guaiacol is quantitatively oxidized by electrolysis on lead dioxide to produce by the intermediary of catechol, methoxyhydroquinone and 3-methoxycatechol, the formic, oxa...

Research paper thumbnail of Direct electrochemical determination of very low levels of 5-hydroxymethyl furfural in natural honey by cyclic and square wave voltammetric techniques

Journal of Electroanalytical Chemistry

Research paper thumbnail of BDD anode for electrochemical removal of parabens in low conductive solution: from a conventional flow cell to a solid polymer electrolyte system

Research paper thumbnail of Electrochemical determination of levofloxacin antibiotic in biological samples using boron doped diamond electrode

Journal of Electroanalytical Chemistry

Abstract The determination of the levofloxacin (LEV) antibiotic in biological samples (urine and ... more Abstract The determination of the levofloxacin (LEV) antibiotic in biological samples (urine and Human serum) using cyclic voltammetry (CV) and square wave voltammetry (SWV) methods was investigated. A boron doped diamond (BDD) was used for the first time as a sensor in the above voltammetric methods. This electrode was used as anode whose electrochemical response showed three irreversible defined peaks. An oxidation mechanism of the molecule has been proposed, including a transfer of 2 electrons and 2 protons leading to LEV N-oxide. Under optimized conditions, CV is less sensitive than SWV method. The latter gave the lowest limit of detection and quantification. LOD and LOQ were found to be 2.88 and 9.60 μmol L − 1 , respectively.

Research paper thumbnail of Descriptive and multivariate analyses of four Tunisian wastewater treatment plants: A comparison between different treatment processes and their efficiency improvement

Journal of Environmental Management, 2017

This study was undertaken to evaluate the performance of four wastewater treatment plants/process... more This study was undertaken to evaluate the performance of four wastewater treatment plants/processes over a 4 year period. The wastewater flow evolution, energy consumption, and quality indicator parameters (BOD 5 , COD and TSS) at the inlet and outlet sites of the plants were determined. In comparing three domestic WWTPs with different wastewater treatment processes, the multivariate analyses (RDA and ANOVA) showed that although the Agareb plant received the highest pollution load, it displayed a high level of removal efficiency especially for COD, BOD, TSS, TKN and NH 4 þ. It also revealed that the fluctuations in the wastewater composition and its contamination by varied industrial discharge could lead to the decrease in performance of the WWTP with activated sludge process as observed for the Southern Sfax plant. However, the electrolysis of the outlet water of Southern Sfax plant showed a significant improvement in COD removal.

Research paper thumbnail of Electrochemical removal of the insecticide imidacloprid from water on a boron-doped diamond and Ta/PbO2 anodes using anodic oxidation process

Korean Journal of Chemical Engineering, 2016

The removal of pesticides from water is a major environmental concern. This study investigates th... more The removal of pesticides from water is a major environmental concern. This study investigates the electrochemical removal of the insecticide imidacloprid (IMD) from aqueous solutions on a boron-doped diamond (BDD) and Ta/PbO 2 anodes under galvanostatic electrolysis. The influence of operating parameters, such as applied current density (50-100 mA cm −2), initial chemical oxygen demand COD (0) (281-953 mg L −1), temperature (25-65 o C) and pH (3.0-10.0) on COD and instantaneous current efficiency (ICE), was studied using the BDD electrode. The degradation efficiency of IMD increased by increasing current density and temperature, but noticeably decreased by the increase of initial pH value and initial concentration of IMD. The COD decay follows a pseudo-first-order kinetic, and the process was under mass transport control. COD removal reaches 90% when using an apparent current density of 100 mA cm −2 , initial COD of 953 mg L −1 , pH of 3.0 and at 25 o C after 4.5 h electrolysis time. Compared with Ta/PbO 2 , BDD anode has shown better performance and rapidity in the COD removal using the same electrolysis device.

Research paper thumbnail of Enhanced degradation of metronidazole by sunlight via photo-Fenton process under gradual addition of hydrogen peroxide

Journal of Molecular Catalysis A: Chemical, 2016

Abstract The present paper has investigated the application of solar energy as renewable, abundan... more Abstract The present paper has investigated the application of solar energy as renewable, abundant, free and clean energy driven advanced oxidation process (photo-Fenton), for the mineralization of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole. The hydrogen peroxide (H 2 O 2 ) was added slowly and gradually over time in order to limit side reactions. The kinetics of organic matter decay was monitored by the chemical oxygen demand (COD) and the absorbance measurements. The experimental results showed that the solar photo-Fenton system leads successfully to 96% of COD removal for 960 mg L −1 COD 0 under optimal experimental conditions (1 mmol L −1 Fe(II) 0 , H 2 O 2 dosing rate of 2 mmol min −1 , pH 3 and at 60 °C) after 12 min. The MTZ concentration decay and the COD removal obeyed a pseudo-first-order kinetics. Compared with Fenton process, the exposition of the reactor to sunlight enhanced the mineralization process by 16%.

Research paper thumbnail of Electrochemical behavior and analytical detection of Imidacloprid insecticide on a BDD electrode using square-wave voltammetric method

Chinese Chemical Letters, 2016

Abstract A sensitive square-wave voltammetric method for the determination of Imidacloprid (IMD) ... more Abstract A sensitive square-wave voltammetric method for the determination of Imidacloprid (IMD) was developed using electrochemically pretreated boron-doped diamond (BDD) electrode. Aqueous solutions were prepared with Confidor 200 SL as the commercial formulation of IMD. Sodium sulfate (Na 2 SO 4 ) was used as supporting electrolyte. The influence of operating parameters, such as the pH of the medium, frequency, pulse amplitude, scan increment and the concentration of IMD was investigated. An irreversible cathodic peak, corresponding to the reduction of IMD is observed at −1.21 V ( vs. SCE) and the electrode reaction was controlled by adsorption. Under optimized conditions, the square-wave reduction peak current was linear over the concentration range of (30–200 μmol L −1 ) with a detection and quantification limits of 8.60 μmol L −1 and 28.67 μmol L −1 , respectively. The results were compared with spectrophotometry and HPLC methods under some conditions and found to be in good agreement. To investigate applicability to real samples, the proposed method was applied to the determination of IMD in plum juice.

Research paper thumbnail of Green electrochemical process for metronidazole degradation at BDD anode in aqueous solutions via direct and indirect oxidation

Separation and Purification Technology, 2016

Abstract Anodic oxidation, an environmentally friendly process has been deeply investigated to re... more Abstract Anodic oxidation, an environmentally friendly process has been deeply investigated to remove the antibiotic metronidazole (MTZ), dissolved in synthetic wastewaters, via direct and indirect oxidation. Experiments were conducted by boron-doped diamond (BDD) anode in the absence and presence of sodium chloride (NaCl) in the solution. However, no studies have focused on the removal of MTZ using BDD anode or under chlorination process. The chemical oxygen demand (COD) measurement during the processing allowed the evaluation of the kinetics of organic matter decay and the instantaneous current efficiency (ICE). The results have shown that the degradation of MTZ is dependent on its initial concentration, pH, applied current density and NaCl concentration. COD decay follows a pseudo first-order kinetics, and the process was under mass transport control within the range studied, regardless of the experimental conditions. The electrochemical degradation is significantly accelerated by the presence of NaCl in the solution (94% COD removal in just 120 min).

Research paper thumbnail of Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

Materials Science and Engineering: C, 2016

The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) a... more The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2-4.2μmolL(-1), with a detection limit of 0.065μmolL(-1).

Research paper thumbnail of Fenton and solar photo-Fenton processes for the removal of chlorpyrifos insecticide in wastewater

Water SA, 2012

The degradation of chlorpyrifos in water by Fenton (H 2 O 2 /Fe 2+) and solar photo-Fenton (H 2 O... more The degradation of chlorpyrifos in water by Fenton (H 2 O 2 /Fe 2+) and solar photo-Fenton (H 2 O 2 /Fe 2+ /solar light) processes was investigated. A laboratory-scale reactor was designed to evaluate and select the optimal oxidation condition. The degradation rate is strongly dependent on pH, temperature, H 2 O 2 dosing rate, and initial concentrations of the insecticide and Fe 2+. The kinetics of organic matter decay was evaluated by means of chemical oxygen demand (COD) measurement. Overall kinetics can be described by a pseudo-second-order rate equation with respect to COD. The optimum conditions were obtained at pH 3, H 2 O 2 dosing rate 120 mg•min-1 , [Fe 2+ ] 0 5.0 mM, initial COD 1 330 mg•ℓ-1 and 35°C for the Fenton process. However, in the solar photo-Fenton process, the degradation rate increased significantly. To achieve 90% of COD removal, the solar photo-Fenton process needs 50% less time than that used in the Fenton process which translates to a 50% gain of H 2 O 2 .

Research paper thumbnail of Electrocatalytic performance of PbO<sub>2</sub> films in the degradation of dimethoate insecticide

Water SA, 2013

This study was performed to find the best experimental conditions for the electrochemical removal... more This study was performed to find the best experimental conditions for the electrochemical removal of the insecticide dimethoate (C 5 H 12 NO 3 PS 2) from aqueous solutions using a lead dioxide niobium anode. The process was studied under galvanostatic polarisation mode. The influence of applied current density (10-50 mA•cm-2), initial chemical oxygen demand COD 0 (100-550 mg•ℓ-1), temperature (30-70°C) and pH (3-11) on COD and instantaneous current efficiency (ICE) was studied. The results showed that almost 90% of COD removal was achieved under optimal experimental conditions, indicating that electrochemical oxidation on a PbO 2 anode is a suitable method for treatment of water polluted with dimethoate. It was found that the decay of COD generally followed a pseudo first-order kinetic and the oxidation rate was favoured by increasing the applied current density, temperature, pH and initial COD. The greatest COD removal (90%) was obtained when using an applied current density of 50 mA•cm-2 , COD 0 = 320 mg•ℓ-1 , pH = 11, T = 70°C and electrolysis time = 8 h.

Research paper thumbnail of Electrochemical degradation of waters containing O-Toluidine on PbO2 and BDD anodes

Journal of Hazardous Materials, 2009

Electrochemical oxidation of O-toluidine (OT) was studied by galvanostatic electrolysis using lea... more Electrochemical oxidation of O-toluidine (OT) was studied by galvanostatic electrolysis using lead dioxide (PbO2) and boron-doped diamond (BDD) as anodes. The influence of operating parameters, such as current density, initial concentration of OT and temperature was investigated. Measurements of chemical oxygen demand were used to follow the oxidation. The experimental data indicated that on PbO2 and BDD anodes, OT oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high temperature. Furthermore, BDD anodes offer significant advantages over PbO2 in terms of current efficiency and oxidation rate.

Research paper thumbnail of Electrochemical degradation of 4-chloroguaiacol for wastewater treatment using PbO2 anodes

Journal of Hazardous Materials, 2006

Electrochemical oxidation of 4-chloroguaiacol (4-CG) at Nb/PbO 2 anodes was studied under differe... more Electrochemical oxidation of 4-chloroguaiacol (4-CG) at Nb/PbO 2 anodes was studied under different experimental conditions such as initial concentration of substrate, electrolysis time, temperature and pH. We measured the concentrations of 4-chlorocatechol (4-CC), 2-methoxyhydroquinone (2-MHQ), maleic acid (MA) and carbon dioxide as the main products. Black solid particles consisting mainly of polymers were formed during electrolysis. A mechanism of electrochemical oxidation of 4-CG was investigated. The oxidation of 4-CG can generally be described by simple pseudo first-order kinetics. The degradation of 4-CG was favoured at high temperature and lower initial concentration of 4-CG and low solution pH. However, the increase of temperature has not a significant effect on the mineralization of carboxylic acids. Moreover, these products required long electrolysis time.

Research paper thumbnail of Kinetic degradation of the pollutant guaiacol by dark Fenton and solar photo-Fenton processes

Environmental Science and Pollution Research, 2011

This work is first intended to optimize the experimental conditions for the maximum degradation o... more This work is first intended to optimize the experimental conditions for the maximum degradation of guaiacol (2-methoxyphenol) by Fenton's reagent, and second, to improve the process efficiency through the use of solar radiation. Guaiacol is considered as a model compound of pulp and paper mill effluent. The experiments were carried out in a laboratory-scale reactor subjected or not to solar radiation. Hydrogen peroxide solution was continuously introduced into the reactor at a constant flow rate. The kinetics of organic matter decay was evaluated by means of the chemical oxygen demand (COD) and the absorbance measurements. The experimental results showed that the Fenton and solar photo-Fenton systems lead successfully to 90% elimination of COD and absorbance at 604 nm from a guaiacol solution under particular experimental conditions. The COD removal always obeyed a pseudo-first-order kinetics. The effect of pH, temperature, H 2 O 2 dosing rate, initial concentration of Fe 2+ , and initial COD was investigated using the Fenton process. The solar photo-Fenton system needed less time and consequently less quantity of H 2 O 2. Under the optimum experimental conditions, the solar photo-Fenton process needs a dose of H 2 O 2 40% lower than that used in the Fenton process to remove 90% of COD.

Research paper thumbnail of Electrochemical degradation of auramine-O dye at boron-doped diamond and lead dioxide electrodes

Diamond and Related Materials, 2012

The electrochemical oxidation of auramine-O (AO) was studied by the galvanostatic electrolysis th... more The electrochemical oxidation of auramine-O (AO) was studied by the galvanostatic electrolysis through the use of the boron-doped diamond (BDD) and the lead dioxide (PbO 2) anodes. The electrolytic process was monitored by the UV-visible spectrometry and the chemical oxygen demand (COD). The results showed that the AO was successfully degraded at both electrodes. This degradation is carried out through hydroxyl radicals electrogenerated from water discharge on the electrode surface. The degradation rate of AO is strongly dependent on its initial concentration, current density and pH. However, temperature has no significant effect. The COD decay follows a pseudo first-order kinetic and the process was under mass transport control. Approximately 95% of COD removal can be obtained under optimal experimental conditions (COD 0 150 mg/L, j app 50 mA/cm 2 , pH 6 and at 30°C). Compared with PbO 2 , the BDD anode showed a better performance to remove the AO. It provided a higher oxidation rate, higher current efficiency and consumed lower energy than the galvanostatic electrolysis using the PbO 2 electrode.

Research paper thumbnail of Influence of anode material and chlorides in the new-gen solid polymer electrolyte cell for electrochemical oxidation – Optimization of Chloroxylenol degradation with response surface methodology

Journal of Electroanalytical Chemistry

Research paper thumbnail of Full paper / Memoire Improvement of the electrocatalytic activity of platinum in oxidation of aromatic compounds

Research paper thumbnail of Anodic oxidation of chlorpyrifos in aqueous solution at lead dioxide electrodes

Journal of Electroanalytical Chemistry, 2010

Research paper thumbnail of Abdelhédi Fenton and solar photo-Fenton processes for the removal of chlorpyrifos insecticide in wastewater

The degradation of chlorpyrifos in water by Fenton (H2O2/Fe 2+) and solar photo-Fenton (H2O2/Fe 2... more The degradation of chlorpyrifos in water by Fenton (H2O2/Fe 2+) and solar photo-Fenton (H2O2/Fe 2+/solar light) processes was investigated. A laboratory-scale reactor was designed to evaluate and select the optimal oxidation condition. The degrada-tion rate is strongly dependent on pH, temperature, H2O2 dosing rate, and initial concentrations of the insecticide and Fe 2+. The kinetics of organic matter decay was evaluated by means of chemical oxygen demand (COD) measurement. Overall kinetics can be described by a pseudo-second-order rate equation with respect to COD. The optimum conditions were obtained at pH 3, H2O2 dosing rate 120 mg∙min –1, [Fe2+]0 5.0 mM, initial COD 1 330 mg∙ℓ –1 and 35 C for the Fenton process. However, in the solar photo-Fenton process, the degradation rate increased significantly. To achieve 90 % of COD removal, the solar photo-Fenton process needs 50 % less time than that used in the Fenton process which translates to a 50 % gain of H2O2.

Research paper thumbnail of A Study of the Electrochemical Oxidation of Guaiacol

The electrochemical oxidation of guaiacol (2-methoxyphenol) on a treated disk of gold was studied... more The electrochemical oxidation of guaiacol (2-methoxyphenol) on a treated disk of gold was studied by cyclic voltammetry. At low concentration, guaiacol undergoes one irreversible anodic peak . The current of this peak has a diffusional origin. For guaiacol concentrations higher than 4 . 10 -2 mol dm -3 , the voltammogram shows a post-peak. The effect of experimental data on the ratio of these two peaks was examined. The proposed mechanism is based on the hypothesis of two-electron oxidation of the guaiacol molecule, involving the intermediary of three phenoxonium cation mesomers. Quantitative importance of these cations is governed by their relative stability. Hydrolysis of these phenoxonium cations would lead to the formation of catechol, methoxyhydroquinone and 3-methoxycatechol. The preliminary results show that guaiacol is quantitatively oxidized by electrolysis on lead dioxide to produce by the intermediary of catechol, methoxyhydroquinone and 3-methoxycatechol, the formic, oxa...

Research paper thumbnail of Direct electrochemical determination of very low levels of 5-hydroxymethyl furfural in natural honey by cyclic and square wave voltammetric techniques

Journal of Electroanalytical Chemistry

Research paper thumbnail of BDD anode for electrochemical removal of parabens in low conductive solution: from a conventional flow cell to a solid polymer electrolyte system

Research paper thumbnail of Electrochemical determination of levofloxacin antibiotic in biological samples using boron doped diamond electrode

Journal of Electroanalytical Chemistry

Abstract The determination of the levofloxacin (LEV) antibiotic in biological samples (urine and ... more Abstract The determination of the levofloxacin (LEV) antibiotic in biological samples (urine and Human serum) using cyclic voltammetry (CV) and square wave voltammetry (SWV) methods was investigated. A boron doped diamond (BDD) was used for the first time as a sensor in the above voltammetric methods. This electrode was used as anode whose electrochemical response showed three irreversible defined peaks. An oxidation mechanism of the molecule has been proposed, including a transfer of 2 electrons and 2 protons leading to LEV N-oxide. Under optimized conditions, CV is less sensitive than SWV method. The latter gave the lowest limit of detection and quantification. LOD and LOQ were found to be 2.88 and 9.60 μmol L − 1 , respectively.

Research paper thumbnail of Descriptive and multivariate analyses of four Tunisian wastewater treatment plants: A comparison between different treatment processes and their efficiency improvement

Journal of Environmental Management, 2017

This study was undertaken to evaluate the performance of four wastewater treatment plants/process... more This study was undertaken to evaluate the performance of four wastewater treatment plants/processes over a 4 year period. The wastewater flow evolution, energy consumption, and quality indicator parameters (BOD 5 , COD and TSS) at the inlet and outlet sites of the plants were determined. In comparing three domestic WWTPs with different wastewater treatment processes, the multivariate analyses (RDA and ANOVA) showed that although the Agareb plant received the highest pollution load, it displayed a high level of removal efficiency especially for COD, BOD, TSS, TKN and NH 4 þ. It also revealed that the fluctuations in the wastewater composition and its contamination by varied industrial discharge could lead to the decrease in performance of the WWTP with activated sludge process as observed for the Southern Sfax plant. However, the electrolysis of the outlet water of Southern Sfax plant showed a significant improvement in COD removal.

Research paper thumbnail of Electrochemical removal of the insecticide imidacloprid from water on a boron-doped diamond and Ta/PbO2 anodes using anodic oxidation process

Korean Journal of Chemical Engineering, 2016

The removal of pesticides from water is a major environmental concern. This study investigates th... more The removal of pesticides from water is a major environmental concern. This study investigates the electrochemical removal of the insecticide imidacloprid (IMD) from aqueous solutions on a boron-doped diamond (BDD) and Ta/PbO 2 anodes under galvanostatic electrolysis. The influence of operating parameters, such as applied current density (50-100 mA cm −2), initial chemical oxygen demand COD (0) (281-953 mg L −1), temperature (25-65 o C) and pH (3.0-10.0) on COD and instantaneous current efficiency (ICE), was studied using the BDD electrode. The degradation efficiency of IMD increased by increasing current density and temperature, but noticeably decreased by the increase of initial pH value and initial concentration of IMD. The COD decay follows a pseudo-first-order kinetic, and the process was under mass transport control. COD removal reaches 90% when using an apparent current density of 100 mA cm −2 , initial COD of 953 mg L −1 , pH of 3.0 and at 25 o C after 4.5 h electrolysis time. Compared with Ta/PbO 2 , BDD anode has shown better performance and rapidity in the COD removal using the same electrolysis device.

Research paper thumbnail of Enhanced degradation of metronidazole by sunlight via photo-Fenton process under gradual addition of hydrogen peroxide

Journal of Molecular Catalysis A: Chemical, 2016

Abstract The present paper has investigated the application of solar energy as renewable, abundan... more Abstract The present paper has investigated the application of solar energy as renewable, abundant, free and clean energy driven advanced oxidation process (photo-Fenton), for the mineralization of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole. The hydrogen peroxide (H 2 O 2 ) was added slowly and gradually over time in order to limit side reactions. The kinetics of organic matter decay was monitored by the chemical oxygen demand (COD) and the absorbance measurements. The experimental results showed that the solar photo-Fenton system leads successfully to 96% of COD removal for 960 mg L −1 COD 0 under optimal experimental conditions (1 mmol L −1 Fe(II) 0 , H 2 O 2 dosing rate of 2 mmol min −1 , pH 3 and at 60 °C) after 12 min. The MTZ concentration decay and the COD removal obeyed a pseudo-first-order kinetics. Compared with Fenton process, the exposition of the reactor to sunlight enhanced the mineralization process by 16%.

Research paper thumbnail of Electrochemical behavior and analytical detection of Imidacloprid insecticide on a BDD electrode using square-wave voltammetric method

Chinese Chemical Letters, 2016

Abstract A sensitive square-wave voltammetric method for the determination of Imidacloprid (IMD) ... more Abstract A sensitive square-wave voltammetric method for the determination of Imidacloprid (IMD) was developed using electrochemically pretreated boron-doped diamond (BDD) electrode. Aqueous solutions were prepared with Confidor 200 SL as the commercial formulation of IMD. Sodium sulfate (Na 2 SO 4 ) was used as supporting electrolyte. The influence of operating parameters, such as the pH of the medium, frequency, pulse amplitude, scan increment and the concentration of IMD was investigated. An irreversible cathodic peak, corresponding to the reduction of IMD is observed at −1.21 V ( vs. SCE) and the electrode reaction was controlled by adsorption. Under optimized conditions, the square-wave reduction peak current was linear over the concentration range of (30–200 μmol L −1 ) with a detection and quantification limits of 8.60 μmol L −1 and 28.67 μmol L −1 , respectively. The results were compared with spectrophotometry and HPLC methods under some conditions and found to be in good agreement. To investigate applicability to real samples, the proposed method was applied to the determination of IMD in plum juice.

Research paper thumbnail of Green electrochemical process for metronidazole degradation at BDD anode in aqueous solutions via direct and indirect oxidation

Separation and Purification Technology, 2016

Abstract Anodic oxidation, an environmentally friendly process has been deeply investigated to re... more Abstract Anodic oxidation, an environmentally friendly process has been deeply investigated to remove the antibiotic metronidazole (MTZ), dissolved in synthetic wastewaters, via direct and indirect oxidation. Experiments were conducted by boron-doped diamond (BDD) anode in the absence and presence of sodium chloride (NaCl) in the solution. However, no studies have focused on the removal of MTZ using BDD anode or under chlorination process. The chemical oxygen demand (COD) measurement during the processing allowed the evaluation of the kinetics of organic matter decay and the instantaneous current efficiency (ICE). The results have shown that the degradation of MTZ is dependent on its initial concentration, pH, applied current density and NaCl concentration. COD decay follows a pseudo first-order kinetics, and the process was under mass transport control within the range studied, regardless of the experimental conditions. The electrochemical degradation is significantly accelerated by the presence of NaCl in the solution (94% COD removal in just 120 min).

Research paper thumbnail of Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

Materials Science and Engineering: C, 2016

The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) a... more The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2-4.2μmolL(-1), with a detection limit of 0.065μmolL(-1).

Research paper thumbnail of Fenton and solar photo-Fenton processes for the removal of chlorpyrifos insecticide in wastewater

Water SA, 2012

The degradation of chlorpyrifos in water by Fenton (H 2 O 2 /Fe 2+) and solar photo-Fenton (H 2 O... more The degradation of chlorpyrifos in water by Fenton (H 2 O 2 /Fe 2+) and solar photo-Fenton (H 2 O 2 /Fe 2+ /solar light) processes was investigated. A laboratory-scale reactor was designed to evaluate and select the optimal oxidation condition. The degradation rate is strongly dependent on pH, temperature, H 2 O 2 dosing rate, and initial concentrations of the insecticide and Fe 2+. The kinetics of organic matter decay was evaluated by means of chemical oxygen demand (COD) measurement. Overall kinetics can be described by a pseudo-second-order rate equation with respect to COD. The optimum conditions were obtained at pH 3, H 2 O 2 dosing rate 120 mg•min-1 , [Fe 2+ ] 0 5.0 mM, initial COD 1 330 mg•ℓ-1 and 35°C for the Fenton process. However, in the solar photo-Fenton process, the degradation rate increased significantly. To achieve 90% of COD removal, the solar photo-Fenton process needs 50% less time than that used in the Fenton process which translates to a 50% gain of H 2 O 2 .

Research paper thumbnail of Electrocatalytic performance of PbO<sub>2</sub> films in the degradation of dimethoate insecticide

Water SA, 2013

This study was performed to find the best experimental conditions for the electrochemical removal... more This study was performed to find the best experimental conditions for the electrochemical removal of the insecticide dimethoate (C 5 H 12 NO 3 PS 2) from aqueous solutions using a lead dioxide niobium anode. The process was studied under galvanostatic polarisation mode. The influence of applied current density (10-50 mA•cm-2), initial chemical oxygen demand COD 0 (100-550 mg•ℓ-1), temperature (30-70°C) and pH (3-11) on COD and instantaneous current efficiency (ICE) was studied. The results showed that almost 90% of COD removal was achieved under optimal experimental conditions, indicating that electrochemical oxidation on a PbO 2 anode is a suitable method for treatment of water polluted with dimethoate. It was found that the decay of COD generally followed a pseudo first-order kinetic and the oxidation rate was favoured by increasing the applied current density, temperature, pH and initial COD. The greatest COD removal (90%) was obtained when using an applied current density of 50 mA•cm-2 , COD 0 = 320 mg•ℓ-1 , pH = 11, T = 70°C and electrolysis time = 8 h.

Research paper thumbnail of Electrochemical degradation of waters containing O-Toluidine on PbO2 and BDD anodes

Journal of Hazardous Materials, 2009

Electrochemical oxidation of O-toluidine (OT) was studied by galvanostatic electrolysis using lea... more Electrochemical oxidation of O-toluidine (OT) was studied by galvanostatic electrolysis using lead dioxide (PbO2) and boron-doped diamond (BDD) as anodes. The influence of operating parameters, such as current density, initial concentration of OT and temperature was investigated. Measurements of chemical oxygen demand were used to follow the oxidation. The experimental data indicated that on PbO2 and BDD anodes, OT oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high temperature. Furthermore, BDD anodes offer significant advantages over PbO2 in terms of current efficiency and oxidation rate.

Research paper thumbnail of Electrochemical degradation of 4-chloroguaiacol for wastewater treatment using PbO2 anodes

Journal of Hazardous Materials, 2006

Electrochemical oxidation of 4-chloroguaiacol (4-CG) at Nb/PbO 2 anodes was studied under differe... more Electrochemical oxidation of 4-chloroguaiacol (4-CG) at Nb/PbO 2 anodes was studied under different experimental conditions such as initial concentration of substrate, electrolysis time, temperature and pH. We measured the concentrations of 4-chlorocatechol (4-CC), 2-methoxyhydroquinone (2-MHQ), maleic acid (MA) and carbon dioxide as the main products. Black solid particles consisting mainly of polymers were formed during electrolysis. A mechanism of electrochemical oxidation of 4-CG was investigated. The oxidation of 4-CG can generally be described by simple pseudo first-order kinetics. The degradation of 4-CG was favoured at high temperature and lower initial concentration of 4-CG and low solution pH. However, the increase of temperature has not a significant effect on the mineralization of carboxylic acids. Moreover, these products required long electrolysis time.

Research paper thumbnail of Kinetic degradation of the pollutant guaiacol by dark Fenton and solar photo-Fenton processes

Environmental Science and Pollution Research, 2011

This work is first intended to optimize the experimental conditions for the maximum degradation o... more This work is first intended to optimize the experimental conditions for the maximum degradation of guaiacol (2-methoxyphenol) by Fenton's reagent, and second, to improve the process efficiency through the use of solar radiation. Guaiacol is considered as a model compound of pulp and paper mill effluent. The experiments were carried out in a laboratory-scale reactor subjected or not to solar radiation. Hydrogen peroxide solution was continuously introduced into the reactor at a constant flow rate. The kinetics of organic matter decay was evaluated by means of the chemical oxygen demand (COD) and the absorbance measurements. The experimental results showed that the Fenton and solar photo-Fenton systems lead successfully to 90% elimination of COD and absorbance at 604 nm from a guaiacol solution under particular experimental conditions. The COD removal always obeyed a pseudo-first-order kinetics. The effect of pH, temperature, H 2 O 2 dosing rate, initial concentration of Fe 2+ , and initial COD was investigated using the Fenton process. The solar photo-Fenton system needed less time and consequently less quantity of H 2 O 2. Under the optimum experimental conditions, the solar photo-Fenton process needs a dose of H 2 O 2 40% lower than that used in the Fenton process to remove 90% of COD.

Research paper thumbnail of Electrochemical degradation of auramine-O dye at boron-doped diamond and lead dioxide electrodes

Diamond and Related Materials, 2012

The electrochemical oxidation of auramine-O (AO) was studied by the galvanostatic electrolysis th... more The electrochemical oxidation of auramine-O (AO) was studied by the galvanostatic electrolysis through the use of the boron-doped diamond (BDD) and the lead dioxide (PbO 2) anodes. The electrolytic process was monitored by the UV-visible spectrometry and the chemical oxygen demand (COD). The results showed that the AO was successfully degraded at both electrodes. This degradation is carried out through hydroxyl radicals electrogenerated from water discharge on the electrode surface. The degradation rate of AO is strongly dependent on its initial concentration, current density and pH. However, temperature has no significant effect. The COD decay follows a pseudo first-order kinetic and the process was under mass transport control. Approximately 95% of COD removal can be obtained under optimal experimental conditions (COD 0 150 mg/L, j app 50 mA/cm 2 , pH 6 and at 30°C). Compared with PbO 2 , the BDD anode showed a better performance to remove the AO. It provided a higher oxidation rate, higher current efficiency and consumed lower energy than the galvanostatic electrolysis using the PbO 2 electrode.