Yanrong Zhang

A novel approach of preparing TiO2 films at low temperature and its application in photocatalytic degradation of methyl orange

Here we introduce a novel approach of preparing TiO(2) films on conductive substrates at low temperature by electrophoretic deposition method without successive calcinate treatment. The photocatalytic activity of the non-calcinated TiO(2) film was evaluated by degradation rate of methyl orange (MO). We found that the degradation rate of MO increased with the amount of TiO(2), and it was higher in both acidic and alkaline media than under neural condition. In addition, lower pH was more favorable for the degradation of MO. The photocatalytic degradation of MO could be described as pseudo-first order reactions. When the initial concentration of MO increased from 1mg/L to 10mg/L, the highest degradation rate was achieved at 5mg/L. The apparent reaction rate constant was calculated to be 0.0098 min(-1).

Electrochemical degradation of PNP at boron-doped diamond and platinum electrodes.

The electrochemical degradation of p-nitrophenol (PNP) at boron-doped diamond (BDD) and platinum (Pt) anodes was studied by varying the parameters such as Cl(-) concentration, pH of aqueous medium and applied current density. The results obtained were explained in terms of in situ concomitant generation of hydroxyl radicals and chloride based oxidant species. The degradation of PNP was highly promoted in low concentration of NaCl electrolyte (less than 0.10 M), on contrary, the mineralization efficiency was poor at both BDD and Pt anodes with the NaCl concentration up to 0.20 M, which was ascribed to the formation of refractory chlorinated organic compounds. A maximum of 100% and 70% of COD removal was achieved in 5h of electrolysis period using both BDD and Pt anodes under similar experimental conditions. Kinetic study indicated that the degradation of PNP at BDD and Pt anodes followed pseudo-first-order reactions, and the reaction rate constant (k(s)) of the former was observed to be higher than that of the latter. Besides COD, conversion of PNP into various intermediate compounds and their degradations were also monitored. The mechanisms for PNP degradation at BDD and Pt anodes were proposed separately by considering the nature of respective intermediate species and their concentrations.