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Papers by hassan oulfajrite
Materials Letters, 2003
New solder alloys are being developed for electronic assemblies in replacement for traditional Pb... more New solder alloys are being developed for electronic assemblies in replacement for traditional Pb-containing solder materials. New low-melting-point, Sn-In-Ag-based alloys have been investigated. Corrosion resistance and the influence of In and Ag content on the electrochemical behaviour have been studied for some Sn-In-Ag special alloys in 3% NaCl solution. The good resistance of this ternary system has been confirmed, and the increase of corrosion resistance with Ag content of Sn-In-Ag alloys has been established.
Journal of Chemical Research, 2003
Portugaliae Electrochimica Acta, 2011
The inhibition efficiency of natural phosphate and kaolin systems in controlling corrosion of sta... more The inhibition efficiency of natural phosphate and kaolin systems in controlling corrosion of stainless steel in HClO4 (0.1 M) solution has been evaluated by electrochemical polarization methods, and electrochemical impedance spectroscopy. The electrochemical data show that the corrosion resistance is greatly enhanced after surface modification. The best protection is obtained with natural phosphate. The uniform coatings of phosphate and kaolin on iron substrates were obtained by electro deposition.
Clay modified carbon paste electrode (CPE-C) its applicability for electroanalysis of N, N’-ethyl... more Clay modified carbon paste electrode (CPE-C) its applicability for electroanalysis of N, N’-ethylene-2,2’-bipyridinium (diquat) has been described in the present work. Electrochemical modification was performed by electronic impedance spectroscopy (EIS) and cyclic voltammetry (CV) in the range of -0.6 V to 1.2 V in 0.1 M K2SO4 (pH 3). The voltammetric method behavior of DQ is suggested where an anodic and cathodic peak appeared at Epa=0.55 V and Epc=0.1 V, successively. These peaks obtained from the reversible redox of DQ at the CPE-C surface. The optimal preconcentration time and percentage of clay insert were 10 min and 20% respectively. The proposed method exhibits certainly an electro-catalytic success toward DQ redox. The peaks current recorded using cyclic voltammetry has been linearly dependent on the DQ concentration ranging from 1×10-5 to 5×10-5 molL-1. The detection limit (DL) calculated for the anodic peak is 5.33×10-8 molL-1. Then relative standard deviation for 2×10-5 m...
A Cyclic voltammetry (VC) method for the determination of trace amounts of paracetamol at carbon ... more A Cyclic voltammetry (VC) method for the determination of trace amounts of paracetamol at carbon paste electrode modified with Clay (ClayCPE) is proposed. The results showed that the Clay-CPE exhibited excellent electro catalytic activity to paracetamol. A quasi-reversible redox process of paracetamol at the modified electrode was obtained. The concentration of paracetamol and measuring solution pH was investigated. This electrochemical sensor shows an excellent performance for detecting paracetamol. The sensor was successfully applied to the determination of paracetamol in a real sample tablets with satisfactory results.
Analytical chemistry, an Indian journal, 2015
The electrochemical behavior of copper ions at natural phosphate modified carbon paste electrode ... more The electrochemical behavior of copper ions at natural phosphate modified carbon paste electrode (NP-CPE) is reported. The electrode paste was prepared as a mixture of finely powdered natural phosphate (NP) together with graphite powder. The influence of variables such as the accumulation time, pH solution, scan rate and concentration tested by cyclic and square wave voltammetry. The best results were obtained under the following optimized conditions: 3 min accumulation time. The electrochemical responses obtained by square wave voltammetry (SWV) and cyclic voltammetry (CV) at NP-CPE were found to be analytically suitable to develop a method for the determination of Cu(II) at low concentration levels. The proposed sensor presented good repeatability, and was applied for cooper determination in tap water samples.
Environmental Science and Technology, 2014
4-aminophenol is themain impurity present in preparations of paracetamol. Using the Cyclic voltam... more 4-aminophenol is themain impurity present in preparations of paracetamol. Using the Cyclic voltammetry, the electrode behaviour of 4-aminophenol has been studied in 0.1 M Na2SO4 solutions at natural phosphate (NP) modified carbon paste electrode (CPE). The optimal potential window of wide range from -1V to 1V was selected. The electron transfer kinetics of theNP-CPE in the detection of analyte was determined by the scan rate effect and concentration variation studies. The scan rate effect showed the electrode process is adsorption controlled. The oxidation peak currents represented a linear dependence on 4-aminophenol concentration from0.45mMto 2.29mMwith correlation coefficient r2=0.996 The effect of cationic surfactant shows good high sensitivity and stability for the redox process of the 4-aminophenol.
A sensitive voltammetric method for detection of mercury ions is described which is made by modif... more A sensitive voltammetric method for detection of mercury ions is described which is made by modifying a carbon paste electrode with clay. A linear working range for concentration of mercury between 0.18mM to 0.91mM. The electrochemical responses obtained by cyclic voltammetry (CV) at clay modified carbon paste electrode (Clay-CPE) were found to be analytically suitable to develop a method for the determination of mercury at low concentration levels. The developed method was applied for the detection of Hg(II) in tap water.
Journal of Drug Metabolism & Toxicology, 2015
We report a sensitive electrochemical voltammetric method for analyzing p-Chloroaniline using a c... more We report a sensitive electrochemical voltammetric method for analyzing p-Chloroaniline using a carbon paste electrochemical (CPE) modified by porous material, such Clay (C). P-Chloroaniline strongly adsorbed on a C-CPE surface and provides facile electrochemical quantitative methods for electroactive p-Chloroaniline (p-CA). Operational parameters have been optimized, and the stripping voltammetric performance has been studied using square wave voltammetry. The peaks current intensity are highly linear, with a good sensitivity of C-CPE. These findings can lead to a widespread use of electrochemical sensors to detect chloroaniline contaminates.
Leonardo Electronic Journal of Practices and Technologies, 2014
A Cyclic voltammetry (VC) and Square Wave Voltammetry methods for the determination of trace amou... more A Cyclic voltammetry (VC) and Square Wave Voltammetry methods for the determination of trace amounts of phenol at carbon paste electrode modified with Natural Phosphate (NP-CPE) is proposed. The results showed that the NP-CPE exhibited excellent electro catalytic activity to phenol. The concentration of phenol and measuring solution pH was investigated. This electrochemical sensor shows an excellent performance for detecting phenol. The sensor was successfully applied to the determination of phenol in a real sample with satisfactory results.
Http Www Theses Fr, 1991
Les hydrates cristallises des acides hsbc16 et h2ptc16 sont des composes a cations hydrates d'... more Les hydrates cristallises des acides hsbc16 et h2ptc16 sont des composes a cations hydrates d'oxonium et a anions globulaires. Haucl#4, 4h#2o a un cation de trihydrate d'oxonium et un anion plan aucl4-. Le but de ce travail est de mieux comprendre la conduction protonique dans ces sels et le passage de l'anion globulaire a l'anion en disque. Les complements apportes sont differents selon les composes: pour hsbcl6, 2h#2o, l'analyse du thermogramme a indique une transformation a 27c et une fusion complexe. Le htr de la transformation est faible. La spectroscopie de vibration, principalement en irft, complete le travail d'hezog-cance et bouzimbou. La liaison hydrogene courte est mise en evidence par les modes de deformation. La rmn (t1) a permis d'identifier les mouvements de h502+ dans son site; pour les hydrates de h2ptcl6, le diagramme de phase est etabli et on a determine l'enthalpie de la transformation a 94c. La spectroscopie de vibration a montre que les cations des 3 composes sont h30+, h502+ et (h502+, h904+). Des mesures de conductivite ont deduit e=0,6 ev; pour haucl4, 4h#2o, la spectroscopie de vibration confirme la presence d'entites h30+ et h502+ conformement a la structure etablie. Les vibrations du reseau du cation ont disparu a 25c. La conductivite, interessante, est assortie d'une energie d'activation voisine de 1,14 ev (conduction ionique, peut etre par h30+)
: This paper reports on the use of carbon paste electrode modified with clay (Clay-CPE) and cycli... more : This paper reports on the use of carbon paste electrode modified with clay (Clay-CPE) and cyclic voltammetry (CV) for analytical detection of trace copper (II) in Na2SO4 0.1M. The electroanalytical procedure for determination of the Cu(II) comprises two steps: the chemical accumulation of the analyze under open-circuit conditions followed by the electrochemical detection of the preconcentrated species using cyclic voltammetry. The electrochemical responses obtained by CV at Clay-CPE were found to be analytically suitable to develop a method for the determination of copper at low concentration levels
Analytical Chemistry
A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical... more A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical sensor for 4-Chloroaniline (4-CA) in aqueous medium. The electrode was prepared by mixed natural phosphate and carbon powder. The influence of accumulation time and pH of the electrolytic solution were investigated. The calibration graph obtained under the optimized conditions was linear. The natural phosphate modified carbon paste electrode was applied to the determination of 4-CA in natural water samples. The results indicate that this electrode is sensitive and effective for the determination of 4-CA.
Analytical chemistry, an Indian journal, 2015
A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical... more A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical sensor for 4-Chloroaniline (4-CA) in aqueous medium. The electrode was prepared by mixed natural phosphate and carbon powder. The influence of accumulation time and pH of the electrolytic solution were investigated. The calibration graph obtained under the optimized conditions was linear. The natural phosphate modified carbon paste electrode was applied to the determination of 4-CAin naturalwater samples. The results indicate that this electrode is sensitive and effective for the determination of 4-CA.
Materials Letters, 2003
New solder alloys are being developed for electronic assemblies in replacement for traditional Pb... more New solder alloys are being developed for electronic assemblies in replacement for traditional Pb-containing solder materials. New low-melting-point, Sn-In-Ag-based alloys have been investigated. Corrosion resistance and the influence of In and Ag content on the electrochemical behaviour have been studied for some Sn-In-Ag special alloys in 3% NaCl solution. The good resistance of this ternary system has been confirmed, and the increase of corrosion resistance with Ag content of Sn-In-Ag alloys has been established.
Journal of Chemical Research, 2003
Portugaliae Electrochimica Acta, 2011
The inhibition efficiency of natural phosphate and kaolin systems in controlling corrosion of sta... more The inhibition efficiency of natural phosphate and kaolin systems in controlling corrosion of stainless steel in HClO4 (0.1 M) solution has been evaluated by electrochemical polarization methods, and electrochemical impedance spectroscopy. The electrochemical data show that the corrosion resistance is greatly enhanced after surface modification. The best protection is obtained with natural phosphate. The uniform coatings of phosphate and kaolin on iron substrates were obtained by electro deposition.
Clay modified carbon paste electrode (CPE-C) its applicability for electroanalysis of N, N’-ethyl... more Clay modified carbon paste electrode (CPE-C) its applicability for electroanalysis of N, N’-ethylene-2,2’-bipyridinium (diquat) has been described in the present work. Electrochemical modification was performed by electronic impedance spectroscopy (EIS) and cyclic voltammetry (CV) in the range of -0.6 V to 1.2 V in 0.1 M K2SO4 (pH 3). The voltammetric method behavior of DQ is suggested where an anodic and cathodic peak appeared at Epa=0.55 V and Epc=0.1 V, successively. These peaks obtained from the reversible redox of DQ at the CPE-C surface. The optimal preconcentration time and percentage of clay insert were 10 min and 20% respectively. The proposed method exhibits certainly an electro-catalytic success toward DQ redox. The peaks current recorded using cyclic voltammetry has been linearly dependent on the DQ concentration ranging from 1×10-5 to 5×10-5 molL-1. The detection limit (DL) calculated for the anodic peak is 5.33×10-8 molL-1. Then relative standard deviation for 2×10-5 m...
A Cyclic voltammetry (VC) method for the determination of trace amounts of paracetamol at carbon ... more A Cyclic voltammetry (VC) method for the determination of trace amounts of paracetamol at carbon paste electrode modified with Clay (ClayCPE) is proposed. The results showed that the Clay-CPE exhibited excellent electro catalytic activity to paracetamol. A quasi-reversible redox process of paracetamol at the modified electrode was obtained. The concentration of paracetamol and measuring solution pH was investigated. This electrochemical sensor shows an excellent performance for detecting paracetamol. The sensor was successfully applied to the determination of paracetamol in a real sample tablets with satisfactory results.
Analytical chemistry, an Indian journal, 2015
The electrochemical behavior of copper ions at natural phosphate modified carbon paste electrode ... more The electrochemical behavior of copper ions at natural phosphate modified carbon paste electrode (NP-CPE) is reported. The electrode paste was prepared as a mixture of finely powdered natural phosphate (NP) together with graphite powder. The influence of variables such as the accumulation time, pH solution, scan rate and concentration tested by cyclic and square wave voltammetry. The best results were obtained under the following optimized conditions: 3 min accumulation time. The electrochemical responses obtained by square wave voltammetry (SWV) and cyclic voltammetry (CV) at NP-CPE were found to be analytically suitable to develop a method for the determination of Cu(II) at low concentration levels. The proposed sensor presented good repeatability, and was applied for cooper determination in tap water samples.
Environmental Science and Technology, 2014
4-aminophenol is themain impurity present in preparations of paracetamol. Using the Cyclic voltam... more 4-aminophenol is themain impurity present in preparations of paracetamol. Using the Cyclic voltammetry, the electrode behaviour of 4-aminophenol has been studied in 0.1 M Na2SO4 solutions at natural phosphate (NP) modified carbon paste electrode (CPE). The optimal potential window of wide range from -1V to 1V was selected. The electron transfer kinetics of theNP-CPE in the detection of analyte was determined by the scan rate effect and concentration variation studies. The scan rate effect showed the electrode process is adsorption controlled. The oxidation peak currents represented a linear dependence on 4-aminophenol concentration from0.45mMto 2.29mMwith correlation coefficient r2=0.996 The effect of cationic surfactant shows good high sensitivity and stability for the redox process of the 4-aminophenol.
A sensitive voltammetric method for detection of mercury ions is described which is made by modif... more A sensitive voltammetric method for detection of mercury ions is described which is made by modifying a carbon paste electrode with clay. A linear working range for concentration of mercury between 0.18mM to 0.91mM. The electrochemical responses obtained by cyclic voltammetry (CV) at clay modified carbon paste electrode (Clay-CPE) were found to be analytically suitable to develop a method for the determination of mercury at low concentration levels. The developed method was applied for the detection of Hg(II) in tap water.
Journal of Drug Metabolism & Toxicology, 2015
We report a sensitive electrochemical voltammetric method for analyzing p-Chloroaniline using a c... more We report a sensitive electrochemical voltammetric method for analyzing p-Chloroaniline using a carbon paste electrochemical (CPE) modified by porous material, such Clay (C). P-Chloroaniline strongly adsorbed on a C-CPE surface and provides facile electrochemical quantitative methods for electroactive p-Chloroaniline (p-CA). Operational parameters have been optimized, and the stripping voltammetric performance has been studied using square wave voltammetry. The peaks current intensity are highly linear, with a good sensitivity of C-CPE. These findings can lead to a widespread use of electrochemical sensors to detect chloroaniline contaminates.
Leonardo Electronic Journal of Practices and Technologies, 2014
A Cyclic voltammetry (VC) and Square Wave Voltammetry methods for the determination of trace amou... more A Cyclic voltammetry (VC) and Square Wave Voltammetry methods for the determination of trace amounts of phenol at carbon paste electrode modified with Natural Phosphate (NP-CPE) is proposed. The results showed that the NP-CPE exhibited excellent electro catalytic activity to phenol. The concentration of phenol and measuring solution pH was investigated. This electrochemical sensor shows an excellent performance for detecting phenol. The sensor was successfully applied to the determination of phenol in a real sample with satisfactory results.
Http Www Theses Fr, 1991
Les hydrates cristallises des acides hsbc16 et h2ptc16 sont des composes a cations hydrates d'... more Les hydrates cristallises des acides hsbc16 et h2ptc16 sont des composes a cations hydrates d'oxonium et a anions globulaires. Haucl#4, 4h#2o a un cation de trihydrate d'oxonium et un anion plan aucl4-. Le but de ce travail est de mieux comprendre la conduction protonique dans ces sels et le passage de l'anion globulaire a l'anion en disque. Les complements apportes sont differents selon les composes: pour hsbcl6, 2h#2o, l'analyse du thermogramme a indique une transformation a 27c et une fusion complexe. Le htr de la transformation est faible. La spectroscopie de vibration, principalement en irft, complete le travail d'hezog-cance et bouzimbou. La liaison hydrogene courte est mise en evidence par les modes de deformation. La rmn (t1) a permis d'identifier les mouvements de h502+ dans son site; pour les hydrates de h2ptcl6, le diagramme de phase est etabli et on a determine l'enthalpie de la transformation a 94c. La spectroscopie de vibration a montre que les cations des 3 composes sont h30+, h502+ et (h502+, h904+). Des mesures de conductivite ont deduit e=0,6 ev; pour haucl4, 4h#2o, la spectroscopie de vibration confirme la presence d'entites h30+ et h502+ conformement a la structure etablie. Les vibrations du reseau du cation ont disparu a 25c. La conductivite, interessante, est assortie d'une energie d'activation voisine de 1,14 ev (conduction ionique, peut etre par h30+)
: This paper reports on the use of carbon paste electrode modified with clay (Clay-CPE) and cycli... more : This paper reports on the use of carbon paste electrode modified with clay (Clay-CPE) and cyclic voltammetry (CV) for analytical detection of trace copper (II) in Na2SO4 0.1M. The electroanalytical procedure for determination of the Cu(II) comprises two steps: the chemical accumulation of the analyze under open-circuit conditions followed by the electrochemical detection of the preconcentrated species using cyclic voltammetry. The electrochemical responses obtained by CV at Clay-CPE were found to be analytically suitable to develop a method for the determination of copper at low concentration levels
Analytical Chemistry
A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical... more A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical sensor for 4-Chloroaniline (4-CA) in aqueous medium. The electrode was prepared by mixed natural phosphate and carbon powder. The influence of accumulation time and pH of the electrolytic solution were investigated. The calibration graph obtained under the optimized conditions was linear. The natural phosphate modified carbon paste electrode was applied to the determination of 4-CA in natural water samples. The results indicate that this electrode is sensitive and effective for the determination of 4-CA.
Analytical chemistry, an Indian journal, 2015
A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical... more A carbon paste electrode modified with natural phosphate (NP) was evaluated as an electrochemical sensor for 4-Chloroaniline (4-CA) in aqueous medium. The electrode was prepared by mixed natural phosphate and carbon powder. The influence of accumulation time and pH of the electrolytic solution were investigated. The calibration graph obtained under the optimized conditions was linear. The natural phosphate modified carbon paste electrode was applied to the determination of 4-CAin naturalwater samples. The results indicate that this electrode is sensitive and effective for the determination of 4-CA.