| Paper industry effluent is enormously discharged, has complicated component and is difficult to process. It contains much chemical composition which threatens human health, such as phenol with phenyl, alkanes and esters etc. In recent years, the situation of environmental pollution is becoming more and more serious, which makes the effluent treatment system must continue to be strengthen on the existing foundation treatment. Photocatalytic degradation of paper industry effluent is a feasible way. There are many kinds of photocatalyst materials, and titanium dioxide is the best choice for semiconductor photocatalyst because it is cheap, easy to get, little pollution and high chemical stability. But the band gap of titanium dioxide is wider, which results in lower response of visible light, so it only uses the ultraviolet light of the solar light, and light degradation efficiency is very low. The modified catalyst has a certain response to visible light, improving the separating and capturing ability of the photo electron and hole, remedying the defect that the optical electron and hole is easy recombination, increasing the photocatalytic efficiency. Cerium and fluorine doped nano titanium dioxide photocatalyst was prepared in this paper, and the photocatalytic properties were tested by degradation of various organics.Finally, the catalyst was used for the treatment of paper industry effluent.The catalyst was prepared by sol-gel method, and its light degradation property was characterized by the degradation rate of COD and chroma of paper industry effluent. The best result of the orthogonal test is doping amount of Ce 1%, doping amount of F 6%, calcination temperature 550℃. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), ultraviolet visible spectrophotometer (UV-Vis) were used to characterize the doping type, doping amount and surface morphology of the catalyst. Results showed that the main crystalline phase of cerium fluoride doped nano titania photocatalyst was anatase. Compared with the commercially available titanium dioxide nanoparticles, cerium fluoride doped titanium dioxide nanoparticles were smaller, more uniform distribution and better dispersion. The results of UV-Vis indicated that the absorption band edge of cerium fluoride doped nano titanium dioxide had obvious red shift, and there was a strong absorption in the visible light range (400-500nm).The performances that cerium fluoride doped nanometer titanium dioxide photocatalyst degrades various organics (phenols, amino, aromatics, ketones, esters) were tested. Results showed that cerium fluoride doped nano titanium dioxide had the degradation effect on all kinds of organics, but the degradation time and degree were different.Influence factors and the mechanism of photocatalytic degradation of paper industry effluent by cerium fluoride doped nano titanium dioxide particles were discussed. Optimum process conditions for the treatment of paper effluent were found. It was the initial pH of effluent 4, the catalyst amount 1.0g/L, and the illumination time 50min. Under this condition, the chroma and CODCr removal raterate reached 95.5% and 90.3%,respectively. Cerium fluoride doped nano titanium dioxide thin film was prepared by dip coating method and used to deeply treat paper industry effluent. Results showed that the chroma and CODCr removal rate reached the maximum when the pH of effluent was 4 and the illumination time was 70min. The reusing result showed that the removal rate was still more than 50% after 6 experiments.This paper showed the treatment effect of modified nano titanium dioxide photocatalyst on paper effluent was obvious. It has certain significance in the application of photocatalytic treatment of paper effluent. |
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