On the behaviour of Atrazine removal from water using fabrics as anodes and cathodes.

This study examines the degradation of atrazine (ATZ) with Pt-modified textile electrodes using an electrochemical method that is comparatively studied in two electrochemical cell configurations: cells with separated anodic and cathodic compartments (divided configuration); and without any separation (undivided configuration). The influence of the presence of chloride ions was studied. The best results were obtained when an undivided cell was used. The morphology and composition of the dispersed Pt coatings were analyzed using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Analysis. The FESEM analyses confirmed that the textile surface was effectively modified by the electrocatalytic material. High performance liquid chromatography, gas chromatography mass spectrometry, and spectroscopic methods were used to follow the evolution of major oxidation products. Total organic carbon, chemical oxygen demand, and total nitrogen were used to evaluate the degradation efficiency of treated aqueous solutions. The experimental results obtained indicate that the efficiency of the electrochemical treatment was high with a low energy consumption when using electrodes based on textile materials, such as anodes or as cathodes (in particular, in electrolysis without compartment separation). All these can be produced at very competitive prices.

Thin bacteria/Layered Double Hydroxide films using a layer-by-layer approach.

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.

Decoloration of orange G (OG) using electrochemical reduction.

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.

A templated electrosynthesis of macroporous NiAl layered double hydroxides thin films.

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.

Glyphosate and glufosinate detection at electrogenerated NiAl-LDH thin films.

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 0.49V/SCE as a function of herbicide concentration in 0.1M NaOH solution. The electrocatalytic response showed a linear dependence on the Glyp concentration ranging between 0.01 and 0.9mM with a detection limit of 1muM and sensitivity 287mA/Mcm(2). The sensitivity found for Gluf was lower (178mA/Mcm(2)).