In this study, the adsorption of an industrial dye Supranol Yellow 4GL onto Cetyltrimethylammoniu... more In this study, the adsorption of an industrial dye Supranol Yellow 4GL onto Cetyltrimethylammoniumbentonite (CTAB-bentonite) is investigated. The organobentonite is synthesised by exchanging cetyltrimethylammonium cations (CTAB) with inorganic ions on the surface of bentonite. The adsorption of Supranol Yellow 4GL onto organobentonite is found to be maximum when the concentration of CTAB exchanged is 100% according to the cation exchange capacity of the clay (CEC). The modification of organobentonite is examined using XRD and FTIR techniques. The effect of the process parameters such as: contact time, adsorbate concentration, adsorbent dose, pH and temperature are reported. Nearly 1200 seconds of contact time are found to be sufficient for the adsorption to reach equilibrium. The pseudo second order model is used to describe the kinetic data, and the rate constant is therefore evaluated. The dye adsorption to organobentonite is characterized by monolayer isotherm and caused by adsorption with relatively strong uptake. The Langmuir and Freundlich models adsorption are applied to describe the isotherm equilibrium and to determine its constants. The Langmuir and Freundlich models agree well with the experimental data with a adsorption capacity of 0.5 g of dye per g of organobentonite. A better fixation was obtained at acidic pH. The effect of temperature on the adsorption of dye has been also studied and the thermodynamic parameters H , S, G,
The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experimen... more The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experiments in laboratory cells. The working electrode consists of a thin grid coated with a layer of nickel in which fine particles of Raney nickel are dispersed. The optimal conditions of decoloration are as follows: basic pH, 0.05 g/L of dye concentration and 0.05 A of current density. Under these conditions, the OG decoloration efficiency reached 100% after only 1800 s of reaction. The observed values of the maximum absorbance in the spectra of the reaction mixture fitted well the polynomials of the fifth degree with respect to reaction time. The initial degradation rate of the dye is obtained easily as the differential coefficient of the functions at initial time. The degradation rate of the dye in the initial stage of the reaction is given by the first-order rate equation. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the decoloration of OG. Direct cathodic reduction ofazo dyes allows decolorization of intensively coloured textile wastewater without addition of chemicals or formation of sludge. The technique is of particular interest for the treatment of concentrated dye baths. The effect of current density, dye concentration, and concentration and nature of the supporting electrolyte on the reduction of the Orange G are reported.
An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) h... more An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Glyp and Gluf is possible at the Ni 3+ centres of the structure. The electrochemical responses of the NiAl-LDH modified electrode were obtained by cyclic voltammetry and chronoamperometry at 0.49 V/SCE as a function of herbicide concentration in 0.1 M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9 mM with a detection limit of 1 M and sensitivity 287 mA/M cm 2 . The sensitivity found for Gluf was lower (178 mA/M cm 2 ).
This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bac... more This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bacterial cells of Pseudomonas sp. strain ADP were assembled alternatively with Mg2Al-NO3 LDH nanosheets by a layer-by-layer deposition method. The UV-Vis spectroscopy was used to monitor the assembly process, showing a progressive increase in immobilized bacteria amount upon deposited cycles. The {ADP/LDH}n film was characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and atomic force microscopy. The metabolic activity of immobilized bacteria was determined using chronoamperometry by measuring the biochemical oxygen demand in presence of glucose using an artificial electron acceptor (Fe(CN)6(3-)) at 0.5V/Ag-AgCl. A steady current of 0.250μAcm(-2) was reached in about 30s after the addition of 5mM glucose.
Journal of Photochemistry and Photobiology A: Chemistry, 2014
The photocatalytic efficiency of colloidal TiO 2 was considerably improved after its immobilizati... more The photocatalytic efficiency of colloidal TiO 2 was considerably improved after its immobilization using synthetic layered double hydroxides (LDHs) as support of the photocatalyst. Compared to conventional colloidal TiO 2 nanoparticles (Q-TiO 2 ), LDHs present the advantage to enhance the contact between an organic pollutant and TiO 2 . This work is focused at the same time on the synthesis of new materials (colloidal TiO 2 /LDHs) and to enhance their efficiency for photodegradation in aqueous solutions of selected dye.
The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experimen... more The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experiments in laboratory cells. The working electrode consists of a thin grid coated with a layer of nickel in which fine particles of Raney nickel are dispersed. The optimal conditions of decoloration are as follows: basic pH, 0.05 g/L of dye concentration and 0.05 A of current density. Under these conditions, the OG decoloration efficiency reached 100% after only 1800 s of reaction. The observed values of the maximum absorbance in the spectra of the reaction mixture fitted well the polynomials of the fifth degree with respect to reaction time. The initial degradation rate of the dye is obtained easily as the differential coefficient of the functions at initial time. The degradation rate of the dye in the initial stage of the reaction is given by the first-order rate equation. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the decoloration of OG. Direct cathodic reduction ofazo dyes allows decolorization of intensively coloured textile wastewater without addition of chemicals or formation of sludge. The technique is of particular interest for the treatment of concentrated dye baths. The effect of current density, dye concentration, and concentration and nature of the supporting electrolyte on the reduction of the Orange G are reported.
Adsorption removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions by bentonite/CTAB was s... more Adsorption removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions by bentonite/CTAB was studied using two ways: the first one using organophilic bentonite as adsorbent. This material was prepared by exchanging the organic cations as cetyltrimethylammonium bromide (CTAB) for sodium (Na + ) on the layer surface of clay (two steps method). The second way was using bentonite as adsorbent, which is in contact with simultaneous 2,4-dichlorophenol and CTAB in solution (one-step method).
Colloidal crystals of polystyrene (PS) beads self-assembled on Pt electrode were used as a sacrif... more Colloidal crystals of polystyrene (PS) beads self-assembled on Pt electrode were used as a sacrificial template to electrosynthesis thin films of macroporous Layered Double Hydroxides (LDH). Such nanostructured materials display a high internal surface area and porosity leading to enhanced electrochemical performance.
An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) h... more An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Glyp and Gluf is possible at the Ni 3+ centres of the structure. The electrochemical responses of the NiAl-LDH modified electrode were obtained by cyclic voltammetry and chronoamperometry at 0.49 V/SCE as a function of herbicide concentration in 0.1 M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9 mM with a detection limit of 1 M and sensitivity 287 mA/M cm 2 . The sensitivity found for Gluf was lower (178 mA/M cm 2 ).
The removal of organophosphate and organophosphonate herbicides from aqueous solution by Ni2Al LD... more The removal of organophosphate and organophosphonate herbicides from aqueous solution by Ni2Al LDH material was investigated. Batch adsorption studies were conducted to evaluate the effect of various parameters such as contact time and initial herbicides concentrations. The adsorption kinetics was tested for Elovich, intraparticle diffusion, pseudo-second-order, and pseudo-first-order reactions and rate constants of kinetic models were calculated. The equilibrium adsorption data were analysed by Freundlich, Langmuir, and Tempkin using linear regression technique. Langmuir isotherms best fitted the data for adsorption equilibrium for both herbicides. Structural and textural analysis (XRD, FTIR, MEB) of Ni2AlNO3 LDH at different rates of adsorption evidence a mechanism of adsorption via an anion exchange reaction, Glyphosate and Glufosinate being adsorbed, in a 1rst step, at the surface of the cristallites and then intercalated in the interlayer domains.
In this study, the adsorption of an industrial dye Supranol Yellow 4GL onto Cetyltrimethylammoniu... more In this study, the adsorption of an industrial dye Supranol Yellow 4GL onto Cetyltrimethylammoniumbentonite (CTAB-bentonite) is investigated. The organobentonite is synthesised by exchanging cetyltrimethylammonium cations (CTAB) with inorganic ions on the surface of bentonite. The adsorption of Supranol Yellow 4GL onto organobentonite is found to be maximum when the concentration of CTAB exchanged is 100% according to the cation exchange capacity of the clay (CEC). The modification of organobentonite is examined using XRD and FTIR techniques. The effect of the process parameters such as: contact time, adsorbate concentration, adsorbent dose, pH and temperature are reported. Nearly 1200 seconds of contact time are found to be sufficient for the adsorption to reach equilibrium. The pseudo second order model is used to describe the kinetic data, and the rate constant is therefore evaluated. The dye adsorption to organobentonite is characterized by monolayer isotherm and caused by adsorption with relatively strong uptake. The Langmuir and Freundlich models adsorption are applied to describe the isotherm equilibrium and to determine its constants. The Langmuir and Freundlich models agree well with the experimental data with a adsorption capacity of 0.5 g of dye per g of organobentonite. A better fixation was obtained at acidic pH. The effect of temperature on the adsorption of dye has been also studied and the thermodynamic parameters H , S, G,
The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experimen... more The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experiments in laboratory cells. The working electrode consists of a thin grid coated with a layer of nickel in which fine particles of Raney nickel are dispersed. The optimal conditions of decoloration are as follows: basic pH, 0.05 g/L of dye concentration and 0.05 A of current density. Under these conditions, the OG decoloration efficiency reached 100% after only 1800 s of reaction. The observed values of the maximum absorbance in the spectra of the reaction mixture fitted well the polynomials of the fifth degree with respect to reaction time. The initial degradation rate of the dye is obtained easily as the differential coefficient of the functions at initial time. The degradation rate of the dye in the initial stage of the reaction is given by the first-order rate equation. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the decoloration of OG. Direct cathodic reduction ofazo dyes allows decolorization of intensively coloured textile wastewater without addition of chemicals or formation of sludge. The technique is of particular interest for the treatment of concentrated dye baths. The effect of current density, dye concentration, and concentration and nature of the supporting electrolyte on the reduction of the Orange G are reported.
An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) h... more An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Glyp and Gluf is possible at the Ni 3+ centres of the structure. The electrochemical responses of the NiAl-LDH modified electrode were obtained by cyclic voltammetry and chronoamperometry at 0.49 V/SCE as a function of herbicide concentration in 0.1 M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9 mM with a detection limit of 1 M and sensitivity 287 mA/M cm 2 . The sensitivity found for Gluf was lower (178 mA/M cm 2 ).
This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bac... more This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bacterial cells of Pseudomonas sp. strain ADP were assembled alternatively with Mg2Al-NO3 LDH nanosheets by a layer-by-layer deposition method. The UV-Vis spectroscopy was used to monitor the assembly process, showing a progressive increase in immobilized bacteria amount upon deposited cycles. The {ADP/LDH}n film was characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and atomic force microscopy. The metabolic activity of immobilized bacteria was determined using chronoamperometry by measuring the biochemical oxygen demand in presence of glucose using an artificial electron acceptor (Fe(CN)6(3-)) at 0.5V/Ag-AgCl. A steady current of 0.250μAcm(-2) was reached in about 30s after the addition of 5mM glucose.
Journal of Photochemistry and Photobiology A: Chemistry, 2014
The photocatalytic efficiency of colloidal TiO 2 was considerably improved after its immobilizati... more The photocatalytic efficiency of colloidal TiO 2 was considerably improved after its immobilization using synthetic layered double hydroxides (LDHs) as support of the photocatalyst. Compared to conventional colloidal TiO 2 nanoparticles (Q-TiO 2 ), LDHs present the advantage to enhance the contact between an organic pollutant and TiO 2 . This work is focused at the same time on the synthesis of new materials (colloidal TiO 2 /LDHs) and to enhance their efficiency for photodegradation in aqueous solutions of selected dye.
The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experimen... more The electrocatalytic hydrogenation of Orange G is investigated using spectrophotometric experiments in laboratory cells. The working electrode consists of a thin grid coated with a layer of nickel in which fine particles of Raney nickel are dispersed. The optimal conditions of decoloration are as follows: basic pH, 0.05 g/L of dye concentration and 0.05 A of current density. Under these conditions, the OG decoloration efficiency reached 100% after only 1800 s of reaction. The observed values of the maximum absorbance in the spectra of the reaction mixture fitted well the polynomials of the fifth degree with respect to reaction time. The initial degradation rate of the dye is obtained easily as the differential coefficient of the functions at initial time. The degradation rate of the dye in the initial stage of the reaction is given by the first-order rate equation. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the decoloration of OG. Direct cathodic reduction ofazo dyes allows decolorization of intensively coloured textile wastewater without addition of chemicals or formation of sludge. The technique is of particular interest for the treatment of concentrated dye baths. The effect of current density, dye concentration, and concentration and nature of the supporting electrolyte on the reduction of the Orange G are reported.
Adsorption removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions by bentonite/CTAB was s... more Adsorption removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions by bentonite/CTAB was studied using two ways: the first one using organophilic bentonite as adsorbent. This material was prepared by exchanging the organic cations as cetyltrimethylammonium bromide (CTAB) for sodium (Na + ) on the layer surface of clay (two steps method). The second way was using bentonite as adsorbent, which is in contact with simultaneous 2,4-dichlorophenol and CTAB in solution (one-step method).
Colloidal crystals of polystyrene (PS) beads self-assembled on Pt electrode were used as a sacrif... more Colloidal crystals of polystyrene (PS) beads self-assembled on Pt electrode were used as a sacrificial template to electrosynthesis thin films of macroporous Layered Double Hydroxides (LDH). Such nanostructured materials display a high internal surface area and porosity leading to enhanced electrochemical performance.
An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) h... more An amperometric sensor based on Ni 1−x Al x (OH) 2 NO 3x ·nH 2 O layered double hydroxide (LDH) has been developed for the electrochemical analysis in one step of two herbicides: glyphosate (N-(phosphonomethyl)glycine, Glyp) and glufosinate ((DL-homoalanine-4-yl)-methylphosphinic acid, Gluf). NiAl-LDH was prepared by coprecipitation or by electrodeposition at the Pt electrode surface. Inorganic films were fully characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Adsorption isotherms of Glyp onto this inorganic lamellar material have been established. Electrocatalytic oxidation of Glyp and Gluf is possible at the Ni 3+ centres of the structure. The electrochemical responses of the NiAl-LDH modified electrode were obtained by cyclic voltammetry and chronoamperometry at 0.49 V/SCE as a function of herbicide concentration in 0.1 M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9 mM with a detection limit of 1 M and sensitivity 287 mA/M cm 2 . The sensitivity found for Gluf was lower (178 mA/M cm 2 ).
The removal of organophosphate and organophosphonate herbicides from aqueous solution by Ni2Al LD... more The removal of organophosphate and organophosphonate herbicides from aqueous solution by Ni2Al LDH material was investigated. Batch adsorption studies were conducted to evaluate the effect of various parameters such as contact time and initial herbicides concentrations. The adsorption kinetics was tested for Elovich, intraparticle diffusion, pseudo-second-order, and pseudo-first-order reactions and rate constants of kinetic models were calculated. The equilibrium adsorption data were analysed by Freundlich, Langmuir, and Tempkin using linear regression technique. Langmuir isotherms best fitted the data for adsorption equilibrium for both herbicides. Structural and textural analysis (XRD, FTIR, MEB) of Ni2AlNO3 LDH at different rates of adsorption evidence a mechanism of adsorption via an anion exchange reaction, Glyphosate and Glufosinate being adsorbed, in a 1rst step, at the surface of the cristallites and then intercalated in the interlayer domains.
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