Photocatalytic Degradatiom Of Dye Effluent By Nano Ce/TiO₂

In recent years, the serious shortage of water resource and the rising voice for the environmental protection in dyeing and printing and dyeing industry resulted in the increasing importance of dyeying effluent treatment technology. The photocatalytic oxidation technology represented by Nano-TiO2 photocatalyst has become a research focus in wastewater treatment due to such advantages as energy efficiency, the complete degradation of pollutants, etc. However, the utilization efficiency of TiO2 to the solar energy is low due to its large band gap. In this research, the nano-TiO2 was doped by Ce4+ in order to broaden its response wavelength rage to the visible light and improve its photocatalytic activity. In addition, microwave was also used in this paper to treat nano-Ce/Ti02 photocatalyst, to further enhance its photocatalytic efficiency. This paper mainly studied the influence factors of this process. The results showed that the optimum condition for the preparation of nano Ce/TiO2 photocatalyst was a molar ratio of 5:1 of acetic acid to titanium alkoxide, a molar ratio of 1:4 of titanium alkoxide to the distilled water, and the calcining temperature of 500℃. Ce/TiO2 dispersed by Dispersant NNO and Carboxymethyl Cellulose(CMC) shows better dispersion stability.The application of Ce/TiO2 to the photocatalytic degradation of dyeing effluent indicated that Ce doping can enhance the photocatalytic activity of nanometer TiO2. Appropriate microwave treatment can also improve the photocatalytic activity of nano-Ce/Ti02 by a certain degree. In addition, the photocatalytic activity is also subject to its dosage, initial concentration of dyeing effluent, light, pH, temperature and some other factors. The photodegradation of the dye effluent by nano Ce/TiO2 and microwave modified nano Ce/TiO2 is better than that of P25. When irradiated in a 400W metal halide lamp (MHL), the decolorization rate reached 86.1% and 99.3%, COD removal rates reached 75.3% and 87.9% respectively. When irradiated in a 100W mercury lamp the decolorization rate reached 97.7% and 98.5%, COD removal rates reached 85.2% and 86.7% respectively.While, irradiated in a 400W metal halide lamp the decolorization rates and COD removal rates of P25 and so prepared pure TiO2 is 89.3%,85.1% and 75.6%,73.7% respectively; When irradiated in a 100W mercury lamp the decolorization rates and COD removal rates is 95.5%,93.2% and 81.9%,80.1% respectively.