Photocatalytic Oxidation Treatment Of Organic Polluted Wastewater

Recently, Photocatalytic Oxidation is a new technique of environment protection which have abroad applied foreground and TiO2, ZnO, Fe2O3, CdS are the most accustomed photocatalysts. Because of two shortcomings that they have only a narrow responding width to natural light and a rapid combination velocity of the stimulated excitons, They don't have high catalytic activities. But by some modification methods, it is possible to heighten their activities. In this dissertation,two kinds of TiO2-catalysts were prepared by sol-gel and dipping process accompanied with some modification ways such as coating the TiO2 on bentonite(including the improvement of its capability), modifying TiO2 with heavy metal or doping it with transitional metal iron. Then the process of producing high activities catalyst under sunlight was confirmed. Without the electron-transmitter H2O2, these two kinds of catalysts can remove the color of the 10mg/l methyl orange in 10-20 minutes when in the sunlight. Its degradation ratio can exceed 90%. When degrading the industrial dyes such as Direct Black L-N and Direct Copper Blue BR of 200mg/l , the color of the dye was almost removed in 30-60 minutes and the degradation ratio of COD can reach 80%-90%. When the reaction time is prolonged, the degradation ratio can exceed 90%.When degrading Direct Black L-N and Direct Copper Blue BR of 400mg/L,the degradation ratio of COD can reach 80% in 50-60 minutes. Experiments indicate:(1)The key of enhance the efficiency of photocatalyst is its preparation,Augment its facies, improve its ability of adsorption can make electron transmitters be adsorbed on photocatalyst effectively, restrain rapid combination of stimulated excitons and produce enough ?OH which has strong oxidability.Thereby,if the exterior capability of photocatalyst is good and it has strong, ability of adsorpion, dissolved O2 in water can be favorable electron transmitters too,and even without H2O2 ,good effect can be acquired.(2) The responding width of photocatalyst can be improved by coating on improved expanding soil, altering character of its surface, sensitezation and intermingling active materials,then the efficiency of photocatalys can be heightened .(3)Onephotocatalyst which has good capability , high activity , vile cost and convenience of reclaim can be made by using vile abio-Ti and appending proper active material.(4)When degrading actual printing and dyeing waste water and refinery waste water ,benign effect can be attained .