Semiconductor Photocatalytic Oxidation Treatment Of Dyeing Wastewater

On the basis of resource, character and treatment approaches inside and outside country of printing and dyeing wastewater, the mechanism, kinetic and technology of photocatalytic treating printing and dyeing wastewater were studied on the laboratory scale in this paper.Experimental water includes analogue dye wastewater and practical printing and dyeing wastewater. Analogue dye wastewater is reactive brilliant red X-3B solution. Practical printing and dyeing wastewater is fetched from the final drain off following fence of Zhongshan Wanbang Underwear Goods Ltd. In the experiment, high pressure mercury lamp whose main wavelength is 365nm and natural sunlight were used as illumination source, catalyst was anatase type titanium dioxide.The main contents of experiment were as follows,Dye X-3B with azo-group was used as treatment project, the mechanism of photocatalytic degradation of organic substance was studied using analytical methods such as UV-Vis absorption spectrum, Ion chromatography, etc. Photocatalytic degradation process of X-3B was proposed on the basis of forerunner's research achievement and the experimental results.In TiOa suspension system, the kinetic of photocatalytic degradation X-3B under the high pressure mercury lamp was studied. The effect factors on the photocatalytic degradation X-3B such as initial mass concentration and pH value of X-3B, intension of UV irradiation, dosages of catalyst, addition H2O2, inorganic negative ions and organic substances were investigated in detail. The results showed that the reaction can be described by Langmuir-Hinshelwood(L-H) equation. The empirical kinetic equation is r = -dc/dt = Kl^Co^Ct. It was found that there is synergistic effect between photodecomposition and photocatalysis by comparing them with each other.On the basis of the studying on mechanism and kinetic, the feasibility of photocatalytic oxidation treating practical printing and dyeing wastewater was studied. Four factors (dosages of catalyst, illumination time, pH value and intension of UV irradiation) which affect photodegradation effect obviously were selected to proceedorthogonal experiments. The optimization technological conditions of printing and dyeing wastewater photocatalysis were determined. Its CODcr is 72.98 mg/L and it is almost decolored totally. It has achieved National First-rate sewage draining level. Millmicron TiOi and Iron-doped TiO2 was applied to treat practical printing and dyeing wastewater for the first time. CODcr of wastewater was reduced effectively.To resolve the problems, that it is hard to separated and recover catalyst, power consumption is large. Photocatalytic degradation of X-3B using fixed TiC>2 and natural sunlight were studied, which is significative to apply the technology to treat wastewater industrially.