Preparation, Characterization And Photocatalytic Properties Of Polyoxometalates Composite Catalyst

The K₈[M（H₂O）MnW₁₁O₃₉]]（M=Ni2+ 、 Zn2+ 、 Fe2+ 、 Co2+）was prepared with the dirctsynthesis method, the PANI/TiO2 was prepared by chemical oxidation method with（NH4）2S2O8 as an oxidant to form polyaniline-wrapped TiO2 nanoparticles, the composite material K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+）was prepared by an electrostatic assembly of K₈[M（H₂O）MnW₁₁O₃₉]]（M=Ni2+、Zn2+、Fe2+、Co2+）and PANI/TiO2.The phase composition, morphologies, stuctures and character of K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+）was characterized by IR、UV、XRD、XPS、SEM、N2 adsorption-desorption.The results showed that: IR、UV、XRD、XPS、SEM prove that the K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+）was successfully synthesized by K₈[M（H₂O）MnW₁₁O₃₉]] and PANI/TiO2, and composite catalyst also possess Keggin structure. The specific surface area of K₈[M（H₂O）MnW₁₁O₃₉]]（M=Ni2+、Zn2+、Fe2+、Co2+） was increased through N2 adsorption-desorption. Thermogravimetric analysis prove that high stability of synthesis of the sample.Photocatalytic activity of K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+）was studied by this experiment. Using 30 W UV lamp as light source. The photocatalytic degradation experiment of gentian violet and malachite green were studied by K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+）. The effect of several different conditions,such as different pH, dosage of catalyst, initial concentration on decolorization of Gentian Violet and malachite green were studied. The K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+） of malachite green, gentian violet catalytic degradation of the optimum conditions are determined respectively. Finally, under optimal conditions, the photocatalytic activity of K₈[M（H₂O）MnW₁₁O₃₉]]/PANI/TiO2（M=Ni2+、Zn2+、Fe2+、Co2+） was compared with its corresponding heteropoly acid salts and intermediates.The experimental results show that the catalytic activity of composite heteropoly acid was superior to heteropoly acid salt and intermediates, The order of catalytic activity is: composite heteropoly acid > heteropoly acid salt > intermediates. The recovery and recycling performance of the catalyst were also explored.