Influence of inorganic anions and organic additives on photocatalytic degradation of methyl orange with supported polyoxometalates as photocatalyst

A novel supported polyoxometalate (POM), phosphotungstic acid immobilized into yttrium-doped TiO2 (HPW-Y-TiO2) nano photocatalyst was prepared via sol-gel and impregnation method. The samples were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and N-2 absorption-desorption analysis. The results showed that the supported POM exhibited Keggin structure and anatase phase with large BET surface area. The influences of inorganic anions and organic additives on the photocatalytic degradation of azo dye methyl orange with HPW-Y-TiO2 as photocatalyst under UV light (lambda >== 365 nm) were investigated. Results showed that inorganic anions Cl-, SO42-, CO(3)(2-)and NO3- had inhibition effect on the degradation of methyl orange. A great enhancement of degradation rate was obtained while H2O2 and ethyl alcohol were applied. The degradation rates improved with the increase of H2O2 concentration. The optimum additive amount of ethyl alcohol was 0.5 mol/L. The possible mechanisms of the effects of additives on methyl orange degradation were discussed.