Experimental And Mechanism Study On Nano-TiO₂ Photocatalytic Degradation Of Organics In Water

Water is one of the substance which is needed by mankind's existence, but now water is shortage in all global, which not only limits economic development, but also threatens the survival of mankind. More and more people are committed to develop water treatment process, and many new techniques are created, photocatalysis is one of them. Because of the characteristics of high oxidant power and no secondary pollution, photocatalytic technology by TiO2 receives high attention in organic waste water treatment. Many scholars pay attention to it as its good prospect. In this paper, preparing supported photocatalyst TiO2 by sol-gel method, taking tetrabutyl titanate as titanium source and 80 mesh stainless steel mesh as a carrier.The results of photocatalytic degradation of LAS show that in the range of 20-50mg/L, the photocatalytic degradation applied to LAS advanced process; the optimum amount of photocatalyst is 2.0g; the removal rate of LAS reaches 95% by photocatalytic after 4h as the initial concentration is 20mg/L; photocatalytic activity is better when the higher pH under alkaline condition and lower pH under acidic condition under the pH range of 2-12.The results of photocatalytic degradation of dimethoate show that in the range of 10-30mg/L, the initial concentration has little effect on photocatalytic degradation, the optimal amount of photocatalyst is 2.0g; the removal rate of dimethoate reaches 92% by photocatalytic after 5h as the initial concentration is 10mg/L; in the range of 2-12, photocatalytic activity is better under alkaline condition than acidic condition, and photocatalytic activity is better when the higher pH under alkaline condition, and lower pH under acidic condition under the pH range of 2-12; H2O2 has great influence on photocatalytic activity, the optimal amount is 15mmol/L when the initial concentration of dimethoate is 10mg/L, and the removal rate is more than 95% after 3h operation.The results of photocatalytic degradation of humic acid show that in the range of 5-100mg/L, the initial concentration has greater influence on photocatalytic degradation. The photocatalytic efficiency increases with the increasing concentration of humic acid, when it reaches a certain concentration, the concentration efficiency basically does not change; when the initial concentration is 10mg/L, the optimum amount of photocatalyst is 1.8g, while the removal rate can reach 77% after 6h; photocatalytic activity is better under lower pH than higher pH under the pH range of 2-12; H2O2 has great influence on photocatalytic activity, the optimal amount of photocatalyst is 10mmol/L when the nitial concentration is 10mg/L, and the removal rate reaches 99% after 2h operation.The paper also analysis dynamic model of these compounds degradation under various conditions. It is found that these three compounds are consistent with first order dynamic model basically in the photocatalytic reaction.