TiO_2光催化降解TCAA及其动力学研究

Research of TiO_2 photocatalytic degradation of TCAA and its Dynamics

三氯乙酸(TCAA)是饮用水中普遍存在,且难以去除的高致癌风险物.考察了通气种类、TiO2用量、溶液初始pH及共存的Fe2+浓度等因素对TiO2光催化降解TCAA效率的影响,分析了pH对TiO2光催化降解TCAA效率的影响机理,探讨了TiO2光催化降解TCAA反应动力学及Fe2+促进TiO2光催化降解TCAA反应的机理.结果表明,当通入气体为O2、TCAA初始浓度为2.0mg/L、TiO2用量为1.0g/L、溶液初始pH为5.80,共存Fe2+浓度为0.10mmol/L时,反应120min,TiO2光催化降解TCAA效率为96.18%;用Langmuir-Hinshelwood模型模拟TiO2光催化降解TCAA反应动力学,UV/TiO2、Fe2+/UV/TiO2反应体系对TCAA的降解速率常数分别为0.0131、0.0237min-1,半衰期分别为52.92和29.25min.

Trichloroacetic acid is a kind of disinfection by-products with high carcinogens risk in drinking water, and it＇s difficult to be removed. The effects of bubbling atmosphere, TiO2 dosage, initial pH values and different concentrations of Fe^2＋ on TiO2 photocatalytic degradation of TCAA are investigated; the mechanism of the impact of pH on TiO2 photoeatalytic degradation of TCAA is also studied. And a discussion of the dynamic kinetics of TiO2 photocatalytic degradation of TCAA and the mechanism of Fe^2＋ proves to be good in promotion of TiO2 photocalalytic degradation of TCAA. Experimental results show that the degradation efficiency is 96.18% after 120 min UV irradiation, when O2 bubbles is applied, with TiO2 dosage being 1.0 g/L, TCAA initial concentration 2.0 mg/L, solution pH 5.8, and the concentration of Fe^2＋ is 0. 1 mmol/L. Moreover, simulation of TiO2 photocatalytic degradation reaction kinetics of TCAA with the Langmuir-Hinshelwood model, the degradation kinetics rate constant of UV/TiO2, Fe^2＋/UV/TiO2 system is 0. 0131 and 0. 0237 min^-1, meanwhile, the half-life is 52.92 and 29.25 min, respectively.