含磁性γ-Fe_2O_3核的TiO_2/Al_2O_3催化剂的制备及光催化性能

TiO2作为光催化剂,可有效地用于水处理,但存在催化剂如何回收再利用和反应器怎样放大设计的问题。该文提出了含磁性核的TiO2催化剂的合成方法,并对典型污染物的降解作了动力学研究,力求解决此类问题。首先,采用共沉法和溶胶-凝胶法制得磁载光催化剂TiO2/A l2O3/γ-Fe2O3,并对该催化剂分别用TEM和XRD进行了形貌和晶相表征。随后,研究了该催化剂对可溶性染料中间体对硝基甲苯邻磺酸(NTS)和直接耐酸大红染料(4BS)的光催化降解性能。结果表明:该催化剂在水溶液中具有良好的分散效果和较高的催化活性,以250 W高压汞灯为光源,经1.5 h的光催化降解,染料去除率可达90%以上;在外加磁场的作用下,催化剂可与液相迅速分离。经实验数据处理,发现NTS在该催化剂上的光催化降解过程符合零级反应动力学模型。

Preparation and Photocatalytic Activity of TiO2/Al2O3 over γ-Fe2O3 Magnetic Core

TiO_2,a photocatalyst,has been extensively used in water treatment.However,it is difficult to separate its fine particles from a solid-liquid slurry system.A synthesis method of a novel photocatalyst with magnetite core was issued in this paper for resolving such a problem.Magnetite matrix Fe_3O_4 was prepared by coprecipitation and γ-Fe_2O_3 was obtained by annealing Fe_3O_4 at higher temperature.Then γ-Fe_2O_3 as core was coated with Al_2O_3 film by coprecipitation,which can efficiently weaken the negative influence of γ-Fe_2O_3 core on the TiO_2 shell.Finally,TiO_2/Al_2O_3/γ-Fe_2O_3 photocatalyst was successfully prepared by sol-gel method.The surface morphology and crystal structure of the catalyst were characterized by TEM and XRD respectively.The photocatalytic activity of this catalyst was determined with nitrotoluenesulfonic acid(NTS) and 4BS dye as decomposition substances.The results showed that the photocatalyst TiO_2/Al_2O_3/γ-Fe_2O_3 can be dispersed in aqueous solution easily and separated from the solution by magnetic field rapidly.After 95 min,the degradation of NTS,irradiated by a 250 W UV lamp,approached 90%.The photo-degradation rate of NTS is zero-order from experimental data analysis.