Study On The Degradation Of Malachite Green By H₃PW₁₂O₄₀-TiO₂/Silica Gel

With the development of dyestuff industry, dye wastewater has increasingly become an important source of environmental pollution, how to treat wastewater reasonably and effectively has become an important issue for researchers. It has important theoretical and practical significance to prepare composite efficient catalyst.In this paper,H3PW12O40-TiO2/Silica gel was obtained by sol-gel and hydrothermal synthesis route,explored the optimal preparation conditions with malachite green solution as the research object,determined the influence of different preparation conditions on the catalytic effect according to orthogonal experiment; the catalyst have been characterized by XRD,TEM, EDS and N2 adsorption-desorption experiments; composite catalyst for malachite green dark adsorption processes were studied under the different temperature conditions; the activities of different catalysts were compared under different lighting conditions for the performance of malachite green;the optimal photocatalytic conditions of the catalysts were explored by dynamics principle at different photocatalytic conditions.The results showed that:the best time of hydrothermal synthesis was 6h,the optimum droping content of H3PW12O40 and silica gel respectively is 12.4% and 25.6%; the time of hydrothermal synthesis had the greatest influence on efficiency of catalyst,followed by silicon doping amount, the doping of H3PW12O40 minimum impact on the efficiency of catalyst the titanium dioxide of H3PW12O40-TiO2/Silica gel was anatase and the phosphotungstic acid still had the structure of Keggin; the catalyst had the structure of microporous and mesoporous; and had significant pore structure; the composite catalyst was in nanometer scale, with uniformity and particle of size of about 10-20nm; catalytic composite H3PW12O40,TiO2 and silica gel were bonded together through certain forces,then formed an efficient composite catalyst; the composite catalyst of H3PW12O40-TiO2/Silica gel for the adsorption process of malachite green in the dark conforms to the Langmuir adsorption model,i.e. monolayer adsorption; compared with the single component of catalyst,the catalytic activity of H3PW12O40-TiO2/Silica gel was obviously improved and the utilization of light was strengthened; the optimal concentration of MG was 20mg/L,at the same time the best dosage of H3PW12O40-TiO2/Silica gel was lg/L, the best treatment effect was in the neutral environment;catalyst also maintained a high photocatalytic properties after three times of recycling.The synergy of H3PW12O40 with TiO2 increased the utilization of light,which were loaded onto silica gel,improved the specific surface area of the catalyst,then enhanced the catalytic activity of catalysts, making the catalyst treat the dye wastewater more efficiently and rapidly.