P. A. Michaud

Oxidation of 4-Chlorophenol at Boron-Doped Diamond Electrode for Wastewater Treatment

The electrochem. behavior of synthetic B-doped diamond thin-film electrode (BDD) was studied in acid media contg. 4-chlorophenol (4-CP) by cyclic voltammetry, chronoamperometry, and bulk electrolysis. The results showed that in the potential region of supporting electrolyte stability occur reactions involving the oxidn. of 4-CP to phenoxy radical and 1,4-benzoquinone. Polymeric materials, which result in electrode fouling, are also formed in this potential region. Electrolysis at high anodic potentials, in the region of electrolyte decompn., complex oxidn. reactions can take place involving electro-generated hydroxyl radicals, leading to the complete incineration of 4-chlorophenol. Electrode fouling is inhibited under these conditions. The exptl. results were compared with a theor. model. This model is based on the assumption that the rate of the anodic oxidn. of 4-CP is a fast reaction. HPLC analyses revealed that the main intermediate products of 4-CP oxidn. were 1,4-benzoquinone, maleic acid, formic acid, and oxalic acid. [on SciFinder (R)]

Electrochemical preparation of peroxodisulfuric acid using boron doped diamond thin film electrodes

The authors have studied the electrochem. oxidn. of H2SO4 on B-doped synthetic diamond electrodes (BDD) obtained by hot filament CVD on p-Si. High current efficiency for H2SO4 oxidn. to peroxodisulfuric acid can be achieved in concd. H2SO4 (>2M) at moderate temps. (8-10 Deg). The main side reaction is oxygen evolution. Small amts. of peroxomonosulfuric acid (Caros acid) also were detected. A reaction mechanism involving hydroxyl radicals, HSO4- and undissociated H2SO4 is proposed. According to this mechanism electrogenerated hydroxyl radicals at the BDD anode react with HSO4- and H2SO4 giving peroxodisulfate. [on SciFinder (R)]

Electrochemical oxidation of water on synthetic boron-doped diamond thin film anodes

Electrolysis in aqueous 1 M HClO4 and 1 M H2SO4 solutions has been carried out under galvanostatic conditions using boron-doped diamond electrodes (BDD). Analyses of the oxidation products have shown that in 1 M HClO4 the main reaction is oxygen evolution, while in H2SO4 the main reaction is the formation of H2S2O8. In both electrolytes small amounts of O3 and H2O2 are formed. Finally, a simplified mechanism involving hydroxyl radicals formed by water discharge has been proposed for water oxidation on boron-doped diamond anodes.

Electrochemical treatment of wastewaters containing organic pollutants on boron-doped diamond electrodes: Prediction of specific energy consumption and required electrode area

A theoretical analysis is presented for the prediction of the specific energy consumption and the required electrode surface for the electrochemical combustion of organic compounds on synthetic boron-doped diamond (BDD) thin film electrodes. The model is formulated for a perfect mixed electrochemical reactor operated as a batch recirculation system under galvanostatic conditions. The anodic oxidation of organics is assumed to be under diffusion control. An experimental validation with the anodic oxidation of phenol and under different experimental conditions is also provided.

Electrochemical oxidation of 3-methylpyridine at a boron-doped diamond electrode: application to electroorganic synthesis and wastewater treatment

The electrochem. oxidn. of 3-methylpyridine (3-MP) at synthetic boron-doped diamond (BDD) thin film electrode was studied in acid media by cyclic voltammetry and bulk electrolysis. The results showed that in the potential region of water stability there can occur direct electron transfer reactions on BDD surface that result in electrode fouling due to the formation of a polymeric film on its surface. While during electrolyzes in the potential region of water decompn., indirect oxidn. reactions can take place by electrogenerated active intermediates, probably hydroxyl radicals that can avoid electrode fouling. Depending on the values of applied c.d., it is possible to obtain the partial oxidn. of 3-MP to nicotinic acid or the complete combustion of 3-MP to CO2. [on SciFinder (R)]

Electro-combustion of polyacrylates with boron-doped diamond anodes

The electro-combustion of water sol. polymeric contaminants such as polyacrylates (PA) in aq. acid soln. using a B-doped diamond anode was studied by bulk electrolysis in 1 mol/dm3 HClO4 under galvanostatic conditions in a wide range of PA concns. and current densities. In all cases complete electro-combustion of PA was achieved and this is the 1st successful report for the electro-combustion of sol. org. polymers. The exptl. COD and instantaneous current efficiency values are well predicted from a theor. model which suppose that the rate of electro-combustion of PA with electrogenerated active intermediates (probably hydroxyl radicals) is a fast reaction and is controlled by mass transport of PA towards the anode (concept of the ideal anode for electro-combustion). [on SciFinder (R)]

Electrochemical Generation of Silver (II) at Boron‐Doped Diamond Electrodes

Synthetic boron-doped diamond (BDD) thin film electrodes were tested for the electrogeneration of silver(II). In nitric acid, the kinetics of the silver(I)/silver(II) couple were studied by cyclic voltammetry. The results demonstrate that silver(II) can be produced with high current efficiency by silver(I) oxidn. at BDD electrodes. At low concn. of nitric acid and high concn. of silver(I), AgO is formed on the electrode surface. [on SciFinder (R)]

Activation of boron-doped diamond with IrO2 clusters

Deposition of small amts. of IrO2 clusters on the B-doped diamond (BDD) surface (BDD-IrO2 electrode) dramatically enhances both the O2 evolution reaction and the oxidn. of orgs. in the potential region of water decompn. The fact that BDD-IrO2 electrode behaves similarly to IrO2-DSA type electrodes suggests that the IrO2 clusters on the BDD surface act as redox catalysts in both oxygen evolution and orgs. oxidn. [on SciFinder (R)]

Electrochemical detection of 2-naphthol on boron-doped diamond: influence of anodic treatment

Synthetic B-doped diamond thin film electrodes were tested for electroanal. detection of 2-naphthol. This redox reaction was studied by cyclic voltammetry in aq. acidic soln. Well-resolved oxidn. waves were obsd. and the voltammetric peaks exhibited naphthol concn. dependence. Linear calibration curves were obtained after a simple electrochem. anodic pretreatment. [on SciFinder (R)]