Abstract:

Six phosphotungstic acid salts of Keggin type such as Mg_1.5PW₁₂O₄₀,Ba_1.5PW₁₂O₄₀,Ca_1.5PW₁₂O₄₀,Na₃PW₁₂O₄₀,K₃PW₁₂O₄₀and (NH₄)₃PW₁₂O₄₀ were prepared by means of liquid phase method and the surface morphologies and microstructures of the samples were characterized by Xray diffraction (XRD) and transmission electron microscopy (TEM). The photocatalytic activities of the catalysts were investigated by photocatalytic degradation of methyl orange with  250 W high pressure mercury lamp as ultraviolet light source. The results show that the six salt particles keep basic Keggin structure frame, belonging to the Keggin structure heteropoly acid type catalyst. The catalysts that have the better activities for the degradation of methyl orange are Mg_1.5PW₁₂O₄₀,Ba_1.5PW₁₂O₄₀and Ca_1.5PW₁₂O₄₀, among which Mg_1.5PW₁₂O₄₀ is the best.

Key words: phosphotungstic acid salts, preparation, photocatalysis