1,721,083 research outputs found
Electrochemical oxidation of para-chlorophenol on Ti/SnO2-PbO2 electrodes: Introduction of a parameter for the estimation of their efficiency.
No full textElectrocatalysis in anodic oxidation of organics with simultaneous oxygen evolution
No full textThe electrochemical oxidation (or combustion) of organics with simultaneous oxygen evolution was studied using different electrode materials (Ti/IrO2, Ti/SnO2). A simplified mechanism for the electrochemical oxidation of organics is presented, according to which selective oxidation occurs with oxide anodes (MOx) for which the formation of higher oxides (e.g.: MOx+1) is possible. Combustion occurs at electrodes at the surface of which OH radicals can be accumulated. Detection of OH radicals formed by water discharge at different anodes using N,N-dimethyl-p-nitrosoaniline (RNO) as a spin trap and preparative electrolysis confirmed the proposed mechanism
Preparation of SnO2-Sb2O5 films by the spray pyrolysis technique
No full textSpray pyrolysis has been widely used for the preparation of thin (approximately 0.1 micron) and transparent SnO2 films on glass substrates. The parameters of the spray pyrolysis for the preparation of thick SnO2-Sb2O5 conductive films on Ti substrates were studied for electrochemical use. The resistivity of the films exhibits a minimum for a Sb concentration of approximately 3 at.% (precursor solution concentration) and for a preparation temperature of 550 °C. As far as the composition is concerned, the Sb concentration in the oxide films is about twice as large as that in the corresponding precursor solution. The dependence of the oxide loading on the substrate temperature and nature and the influence of the spray conditions also are discussed
Service life of Ti/SnO2-Sb2O5 anodes
No full textThe service life of SnO2-Sb2O5 coated anodes prepared by the spray pyrolysis technique using Ti or Ti/IrO2 substrate, was studied under galvanostatic conditions (100mA/cm2 in 1M H2SO4 at 25 °C). The results showed that the presence of an IrO2 interlayer between the Ti substrate and the SnO2-Sb2O5 coating (Ti/IrO2/SnO2-Sb2O5 anode) strongly increases the service life of the anode. This beneficial action of the IrO2 interlayer was attributed to its high anodic stability and its isomorphous structure with TiO2 and SnO2. Cyclic voltammetry and steady-state polarization curves showed that the electrochemical behaviour of the Ti/IrO2/SnO2-Sb2O5 electrode lies between the behaviour of the Ti/IrO2 and the Ti/SnO2-Sb2O5 electrodes due to incorporation of IrO2 in the SnO2-Sb2O5 coating during its preparation
Electrochemical treatment of wastewaters containing organic pollutants on boron-doped diamond electrodes. Prediction of specific energy consumption and required electrode area
No full textA 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 4-chlorophenol for wastewater treatment - Definition of normalized current efficiency (phi)
No full textThe electrochemical behavior of lead dioxide and synthetic boron-doped diamond thin film electrodes BDDs has been studied in acid media containing 4-chlorophenol 4-CP by bulk electrolysis under different experimental conditions. In order to quantify the electrochemical activity of a given electrode, for the electrochemical oxidation of organic compounds 4-CP, the current efficiency of the anodic oxidation has been normalized taking into consideration mass-transport limitations. The normalized current efficiency has been defined as the ratio between the current efficiency of the investigated anode to the current efficiency of an ideal anode which has a very fast oxidation rate, resulting in a complete combustion of organics to carbon dioxide. The results have shown that even if the complete combustion of 4-chlorophenol has been achieved at both lead dioxide and boron-doped
diamond anodes, the latter give higher. The difference in reactivity of the electrogenerated hydroxyl radicals on the anode surface, has been proposed to explain the high values obtained using boron-doped diamond anodes
The Anodic Oxidation of 2-Naphthol at Boron-Doped Diamond electrodes
No full textThe anodic oxidation of 2-naphthol in acid media was investigated at a synthetic boron-doped diamond thin film electrode (BDD) using cyclic voltammetry and bulk electrolysis. The results have shown that in the potential region, where the supporting electrolyte is stable, reactions involving simple electron transfer, such as oxidation of 2-naphthol to naphthoxy radical and 1,4-naphthoquinone occur. Polymeric materials, which lead to electrode fouling, are also formed in this potential region. Electrolysis at high positive potentials in the region of electrolyte decomposition causes complex oxidation reactions by electrogenerated hydroxyl radicals leading to the complete incineration of 2-naphthol. Electrode fouling is inhibited under these conditions. The experimental results have been also compared with a theoretical model. This model is based on the assumption that the rate of the anodic oxidation of 2-naphthol is a fast reaction and it is under diffusion contro
Electrochemical properties of Ti/SnO2-Sb2O5 electrodes prepared by the spray pyrolysis technique
No full textCyclic voltammetry for the ferri-ferrocyanide redox couple was used to study the Ti/SnO2-Sb2O5 electrode prepared by spray-pyrolysis under different conditions. Increasing the preparation temperature and the duration of coating deposition results in a decrease of ip and an increase of Ep for the ferri-ferrocyanide couple. This deviation from reversibility is attributed to the formation of a titanium oxide layer at the Ti/coating interface. Concerning oxygen evolution at the Ti/SnO2-Sb2O5 anodes, a mechanism is proposed in which water is discharged at the anode forming hydroxyl radicals which are further oxidized to form dioxygen. Finally, a generalized mechanism for oxygen evolution at oxide electrodes is proposed
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