Study On The Visible Light Response To Photocatalytic Degradation Of Dye Waste Water

The polyoxometalate - K6SiW11O39Snâ…¡(SiW11Snâ…¡) was synthesized and characterized by IR and UV-Vis spectrogram in the thesis. The characteristic of its photocatalytic degradation to methyl red aqueous solution was investigated with indoor scattered light and outdoor sunlight. The SiW11Snâ…¡/PVA complex film(PVA: Polyvinyl alcohol ) prepared by chemical self-assembled method was characterized. The effect of photocatalytic decoloration of methyl red solution with SiW11Snâ…¡and SiW11Snâ…¡/PVA was compared and discussedThe result shows that the initial concentration of methyl red solution,catalyst quantity and irradiation light source all had effects on the decolorization, TOC and COD removal rates of the methyl red solution. When the initial concentration of methyl red solution(10ml) was 10mg/L, pH was 4.00, the concentration of the catalyst was 1g/L, the methyl red solution was irradiated 6h indoor scattered light, the decolorization rate of which was 98%, TOC and COD removal rates of it were 84.2% and 89.6%, respectively. When the average irradiation intensity of outdoor solar was 78000 lx, it need only 1h to get the same above results.The SiW11Snâ…¡/PVA complex film was prepared by chemical self-assembled method. Except the initial concentration of methyl red solution,catalyst quantity and irradiation light source had effects on the photocatalytic degradation results when SiW11Snâ…¡/PVA complex film was used as photocatalyst, the ratio of POMs to PVA in the SiW11Snâ…¡/PVA complex film,drying time and drying temperature of SiW11Snâ…¡/PVA complex film had effects, too. When the mass ratio of SiW11Snâ…¡to PVA was 2:1, the best complex film could be obtained, and the film had better effect on photocatalytic degradation of methyl red solution. It took 8 h and 12h to achieve the same above results when SiW11Snâ…¡/PVA complex film was used as photocatalyst with indoor scattered light and outdoor daylight, respectively. Although the catalytic efficiency of the immobilized SiW11Snâ…¡/PVA complex film catalyst was decreased, the problem for separation catalyst from solution was solved and it could be reused. The catalytic activity of SiW11Snâ…¡/PVA complex film was almost unchanged, after being centrifugated, washed, dried, and recycled three times .