可见光下F-TiO_2催化剂对2,4,6-三氯苯酚光催化活性研究

F-TiO_2 photocatalytic activity for 2,4,6-trichlorophenol under visible light irradiation

2,4,6-三氯苯酚对人体健康和生态环境产生较大的危害,是我国水环境优先监测污染物之一,论文采用溶胶-凝胶法制备了F-TiO_2光催化剂,利用XRD,UV-DRS,XPS,BET等对其理化性质进行了表征,考察了F-TiO_2在可见光下对2,4,6-三氯苯酚的催化降解,并结合其脱氯和矿化情况探讨了2,4,6-三氯苯酚的降解机理。结果表明,与纯的TiO_2相比,掺氟后的TiO_2增强了在可见光区的吸收,F与Ti的摩尔比为0.05时,催化剂晶粒尺寸为14.26 nm,TiO_2仅存在高活性的锐钛矿相;在可见光下2,4,6-三氯苯酚反应4h,其降解率可达93%;反应12h后,降解率为100%,完全被降解,达到了安全化处理的标准。分析2,4,6-三氯苯酚降解过程中的脱氯率、降解率和矿化率,推断其降解过程分为三个阶段:第一是羟化脱氯阶段,第二是氧化开环与脱氯并存阶段,最后是彻底氧化分解阶段。

2,4,6-trichlorophenol is harmful to human health and ecological environment,which is one of the priority monitoring pollutants for water environment in China. In this paper,F-TiO_2 photocatalyst was prepared by sol-gel method. The physicochemical properties of the catalyst were characterized by XRD,XPS,UV-DRS,BET.The degradation for 2,4,6-trichlorophenol was investigated by F-TiO_2 under visible light irradiation. Then the degradation mechanism of 2,4,6-trichlorophenol was discussed combining with dechlorination and mineralization.The results indicated that compared with pure TiO_2,the absorption of F-TiO_2 was enhanced in the visible region.When the mole ratio of F/Ti was 0. 05,the catalyst grain size was 14. 26 nm,and TiO_2 had only highly active anatase.The degradation rate of 2,4,6-trichlorophenol is up to 93%under visible light irradiation for 4h; It can be completely degraded after 12 h,which reached the standard of safe treatment.Analyzing the process of degradation rate,dechlorination rate and mineralization rate during the degradation for 2,4,6-TCP,it is concluded that the degradation process can be divided into three stages： the hydroxylation dechlorination,the oxidative ring-opening and dechlorination,the complete oxidation decomposition.