TiO_2光催化降解苯和甲苯的动力学研究

Kinetic Study on Photocatalytic Degradation of Toluene and Benzene over TiO_2 Nanoparticles

利用溶胶-凝胶法制备了粒径约为13nm、晶型为锐钛矿相和金红石相混晶的TiO2光催化剂,并利用此催化剂对挥发性有机污染物苯和甲苯进行了光催化降解研究,对不同的催化剂用量、光源、污染物的初始浓度以及氧气对光催化反应速率的影响进行了研究。结果表明,光催化降解甲苯和苯的反应均符合假一级动力学方程,光强与光催化降解甲苯的反应的速率常数之间呈指数关系,光波长对光催化降解苯的影响也很显著;随着甲苯和苯初始浓度的增加,光催化反应速率常数降低;氧气加快了光催化降解甲苯和苯的速率;对于光催化降解初始浓度为37.6μmol/L的甲苯而言,催化剂的最佳使用量为0.30g,对于光催化降解初始浓度为9.0μmol/L的苯来说,催化剂的最佳用量为0.10g。

Rutile and anatase mixture of TiO2 nanoparticles were prepared through sol-gel method. These nanoparticles show a narrow size distribution around 13nm. The photocatalytic properties of the samples were tested on degradation of volatile organic contaminants（VOCs）, toluene and benzene. The effects of photocatalyst amount, illumination source, original concentration of toluene and benzene and the existence of oxygen on photocatalytic reaction rate were investigated. The results showed that the reactions of photocatalytic oxidation of toluene and benzene followed pseudo first-order kinetic equation. The rate constant of toluene degradation showed exponentially with irradiation intensity. Light wavelength could affect obviously photocatalytic efficiency of degrading benzene. Photocatalytic reaction rate decreased with original concentration of toluene and benzene increasing. Oxygen could accelerate photocatalytic reaction of oxidizing benzene and toluene. When the original concentration of toluene is 37.6μmol/L, benzene 9.0μmol/L, the optimal amount of photocatalyst is about 0.30g and 0. 10g respectively.