A novel composite based on Titanium oxide and clays hydrothermally was synthesized to be used as substrate in advanced treatment of wastewaters. The treatment consists of one single step process combining photocatalysis and adsorption. The composite's crystalline structure is investigated by X-ray diffraction and FTIR, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to analyze the surface morphology. The adsorption capacity and photocatalytic properties of the material are tested on pollutants matrix containing dye (Methylene Blue) and heavy metal (cadmium cation). The results under optimized conditions indicate a good removal efficiency using this novel composite material.

Pt, 50 RuO 2 and 50 IrO 2 electrodes were prepared on titanium (Ti) substrate by thermal decomposition techniques. The micrographs of 50 Pt-50 RuO 2 and 50 Pt-50 IrO 2 have revealed that their surfaces are rough with cracked structures in contrast to platinum which exhibits smooth, compact and homogeneous surface. The richer the electrode surface in platinum, thinner is the crack size and also more compact is the electrode surface. The electrodes have also been characterized electrochemically by cyclic voltammetry in acidic (HClO 4 ) and alkaline (KOH) electrolytes. These characterizations showed that the surface electrodes let them possess higher electrocatalytic activity towards OER than Pt in the two media. Though the kinetic of the oxygen evolution reaction is practically the same in acidic and alkaline media for all the electrodes, OER occurred at lower overpotential in alkaline electrolyte than in acidic electrolyte on the prepared electrodes.

The environment pollution, in particular that of the aquatic environment, by wastewater is a reality because it is discharged for the most part without treatment. The presence of pharmaceutical pollutants such as paracetamol in these waters can constitute a risk to human health. The objective of this work is to study the electrochemical oxidation of paracetamol using cyclic voltammetry on the boron doped diamond (BDD) anode and boron doped diamond modified by gold particles (Au-BDD) anode. The Au-BDD electrode was obtained by modifying the surface of BDD with gold particles. This was done by electrodeposition (chronoamperometry) in 0.5 M HAuCl4 and 0.1 M H2SO4 using a three pulse nucleation and growth process. Physical characterization with Scanning Electron Microscopy coupled with Dispersive Energy spectroscopy has shown that the Au-BDD surface presents asperities with the presence of microparticles and nanoparticles. The electrochemical characterization made in three electrolytic solutions (H2SO4, NaOH and KClO4) showed that Au-BDD has a high electroactivity domain than that of BDD. The study of the Benzoquinone-hydroquinone redox couple has shown a quasi-reversible character of these two anodes. It also revealed that Au-BDD has a more accentuated metallic character than BDD. The voltammetric measurements made it possible to show that the paracetamol oxidation is limited by the transport of material on each anode. This oxidation is characterized by the presence of an anodic peak in the support electrolytes stability domain. The paracetamol oxidation is rapid on Au-BDD than on BDD in the various medium explored, thus showing that Au-BDD is more efficient than BDD for the paracetamol oxidation by electrochemical means.

This work aimed to contribute to the mechanism electrochemical oxidation study of organic compounds on DSA electrodes. To do this, IrO₂ and RuO₂ electrodes were prepared thermally at 40°C on Titanium substrate. The prepared electrodes were characterized using voltammetric and SEM techniques. The electrochemical measurements in acid media made it possible to show the presence of IrO₂ and RuO₂ on the surface of the electrode. These electrodes have identical electrocatalytic behaviors both for oxygen evolution and chlorine evolution. The prepared electrodes make it possible to oxidize the organic compounds in an acid media in the absence or in the presence of Cl^-. In acidic electrolytes, water molecules produce hydroxyl radicals that contribute to the higher oxides (RuO₃ or IrO₃) formation. The higher oxides obtained produce O₂ and regenerate the active sites of our electrodes. In the electrolytes containing chlorides, higher oxides fix them (IrO₃(Cl) or RuO₃(Cl)) in competition with the production of O₂. Then IrO₃(Cl) or RuO₃(Cl) reacts with Cl^- to produce Cl₂ and regenerate the adsorbed hydroxyl radicals. The higher oxides also react as a mediator in HCOOH oxidation in competition with O₂ evolvement. In the electrolytes containing HCOOH and Cl^-, the organic pollutant's oxidation occurs indirectly via the hypochlorite ions produced in the solution and on the electrodes. This study showed that the produced OH· and Cl₂ in situ are involved in the oxidation of HCOOH

A nanostructured gold-silver soaked in polyethylene glycol 400 (Au-Ag@PEG) is designed using gold(I) chloride and silver nitrate (AgNO 3) as precursors and, polyethylene glycol 400 (PEG) as capping agent. The result of the structure characterization using Selected Area Electron Diffraction (SAED) has showed that the synthesized nanomaterial has a good crystallinity while Transmission Electron Microscopy (TEM), energy dispersive X-ray spectrometry (EDX) and Dynamic Light Scattering (DLS) measurements suggest mixed Au-Ag nanoparticles with an average diameter size of around 7 nm and 30 nm for Au and Ag respectively.

Biological treatment, due to its low installation cost, is widely used for wastewater treatment. However, this treatment remains ineffective for the oxidation of so-called emerging molecules. To solve this environmental problem, advanced oxidation processes (AOPs) combine with Biological treatment for rapid, efficient and cost-effective purification of wastewater. This combination used in this work, allowed a total mineralization of a real wastewater solution from the teaching hospital of Treichville named CHU of Treichville in Abidjan (CHUT), both in terms of organic and microbiological pollutants. Real wastewater from the CHUT underwent a Biological treatment for 28 days via the Zahn-Wellens methods which made it possible to have a reduction rate of the chemical oxygen demand of more than 90% of biologically active organic pollutants. The biologically treated wastewater was doped with ceftriaxone (CTX) to simulate a situation of wastewater containing a recalcitrant compound after Biological treatment. Subsequently, the doped solution underwent treatment with different AOPs (UV / H2O2, Fe2+ / H2O2 and UV / Fe2+ / H2O2). This combination resulted in a COD reduction rate of over to be higher 98% and total inactivation of microbiological germs.

The platinum anode modified by metal oxides electrodes degrades Abidjan wastewater which contains a high concentration of Cl-. During this degradation process, the organic polluants are oxidized, O2 and Cl2 are produced. The purpose of this study is to contribute to the understanding of these reaction mechanisms by studying the kinetics of O2 and Cl2 evolution at neutral pH on Pt. The study was performed by interpreting the voltammograms and Tafel slopes obtained. The voltammetric measurements were carried out using an Autolab Potentiostat from ECHOCHEMIE (PGSTAT 20) connected by interface to a computer. Pt electrode was prepared on titanium (Ti) substrate by thermal decomposition techniques at 400°C. The characterization of the surface of the prepared electrode by scanning electron microscopy and X-ray photoelectron spectrometry showed the presence of platinum on its surface. The results obtained show that the OH· are adsorbed on the active sites of Pt. Then they react to form PtO. Then by reaction between the surface oxygen and PtO, O2 is produced and the active sites are regenerated. In the presence of low Cl- concentration, there is a competition between the Cl2 and O2 evolution reactions. However, Cl2 only is produced for high Cl- concentrations. The kinetics of the evolution reaction of chlorine increases with the concentration of Cl- and remains constant for concentrations greater than 0.5 M. This study also showed that the chlorine reduction reaction produced in solution is a diffusion-controlled reaction for low scan rates.