et expliquer les phénomènes à l'origine de la minéralisation de ces eaux. Méthodologie and résultats : Dix-sept paramètres physico-chimiques sont déterminés pour chacun des 7 échantillons d'eaux. Les résultats sont traités à l'aide de méthodes hydrochimiques (diagramme de Piper) pour l'étude de la typologie des eaux et des techniques d'analyse statistique multivariée. L'Analyse en Composantes Principales Normées (ACPN) et l'analyse en Classification Hiérarchique Ascendante (CHA) sont utilisées pour mettre en évidence respectivement les phénomènes à l'origine de la minéralisation des eaux et les liens entre ces eaux. Les eaux étudiées sont acides (5,09 ˂pH ˂7,43) et très faiblement minéralisées (CE˂˂100 µScm-1). Les teneurs des paramètres chimiques sont inférieurs aux normes OMS ; excepté, la silice (15,8 mg/L à 56,8 mg/L) et les éléments métalliques en traces : le fer (0,31 à 3,82 mg/L), le manganèse (0,019 à 0,264 mg/L) et l'aluminium (0,02 à 0,232 mg/L). Les eaux sont dans la majorité chlorurées sodi-potassiques. Trois phénomènes sont à l'origine de la minéralisation des eaux : les apports des activités anthropogéniques, le pluviolessivage des sols et le contact eau-roche (principal mécanisme de production d'ions). Trois groupes d'eaux sont obtenus. La Bia se distingue des autres eaux par son importante composition chimique. Conclusion et applications : Cette étude révèle que 43% des eaux de surface de la région d'Adiaké subissent une pollution anthropique importante. En dehors de la contamination bactérienne non traitée, cette étude montre que les eaux du Toumanguié, de l'Ehania et de la lagune Ehy peuvent représenter d'importantes réserves pour l'approvisionnement en eau potable de la région.

This study was conducted to characterize virulence genes of Escherichia coli isolates from water, sediment, fish, and crab in Aby Lagoon. Serogrouping was performed by EPEC antisera in 113 E. coli strains. The presence of diarrhea-associated genes (eae, stx, AggR, elt, and est) was assessed by multiplex PCR using specific primers. Based on the multiplex PCR, sixty-two isolates (42 from water, 19 from sediment, and 1 from crab) were positive for virulence genes, including 34 positive for elt (ETEC), 46 positive for est (ETEC), 24 positive for both elt and est, 6 positive for stx (EHEC), 1 positive for both stx + est, and 1 positive for both stx + elt. Genes eae (EPEC) and AggR (EAEC) were not detected. Nine serogroups (O114, O127, O55, O111, O86, O119, O126, O128, and O142) were identified. This study revealed the presence of diarrheagenic and nondiarrheagenic E. coli and potential public health risks if fishery products are not appropriately cooked.

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.

Electrochemical oxidation of paracetamol on boron-doped diamond (BDD) anode has been studied by cyclic voltammetry and preparative electrolysis. Quantification of paracetamol during electrolysis has been mainly realized by differential pulse voltammetry technique in the Britton-Robinson buffer solutions used as the supporting electrolyte. Various parameters such as current intensity, nature of the supporting electrolyte, temperature, and initial concentration of paracetamol have been investigated. The electrochemical characterization by the outer sphere Fe(III)/Fe(II) redox couple has also been performed, showing the metallic character of BDD electrode. The obtained linear dependency of the oxidation peak current intensity and paracetamol concentration indicates that BDD electrode can be used as an electrochemical sensor for the detection and quantification of paracetamol. The investi­gation of paracetamol degradation during preparative electrolysis showed that: (i) the degradation rate of paracetamol increases with increase of current intensity applied; (ii) for the initial concentrations of 10, 6 and 1 mM of paracetamol, its oxidation rate reaches 60, 78 and 99 % respectively, after 1 h of electrolysis in 0.3 M H2SO4 (pH 0.6) at applied current density of 70 mA cm-2; (iii) at temperatures of electrolyte solution of 28, 55 and 75 °C, paracetamol oxidation rate reached 85, 92 and 97 % respectively, after 2 h at applied current density of 70 mA cm2. From the investigation of the effect of pH value of electrolyte solution, it appears that oxidation of paracetamol is more favorable in acidic solution at pH 3 than solutions of higher pH values.