臭氧/纳米TiO_2催化氧化去除水中微量硝基苯的研究

Degradation of Trace Nitrobenzene by Nanosized TiO_2 Catalyzed Ozonation

在悬浮颗粒搅拌混合反应器中,研究了臭氧/纳米TiO2催化氧化去除水中微量硝基苯的性能,结果表明,纳米TiO2催化臭氧化去除硝基苯较单独臭氧氧化有明显的提高,反应20min硝基苯的去除率提高了44%.实验中分别考察了纳米TiO2热处理温度、催化剂投量、臭氧投量、硝基苯初始浓度、pH值对臭氧/纳米TiO2催化氧化去除硝基苯的影响.发现550℃烧结得到的纳米TiO2表现出最好的催化臭氧化活性,在较低的臭氧投量与催化剂用量条件下,硝基苯的去除率可达到56.57%;增大臭氧或者硝基苯的初始浓度,硝基苯的去除率随之提高;但是改变催化剂投量,硝基苯的去除效果几乎不受影响;中性或碱性pH环境利于纳米TiO2催化臭氧化反应的进行.通过研究叔丁醇对纳米TiO2催化臭氧化反应的影响,证明反应遵循羟基自由基(.OH)反应机理.

Nanosized TiO2 catalyzed ozonation of trace nitrobenzene in water was carried out in an agitated slurry semi-batch. It demonstrated that removal rate of nitrobenzene with catalytic ozonation increased by 44% than ozonation alone. Effect of heat treatments of TiO2, catalyst mass, the initial concentration of ozone and nitrohenzene, and pH were investigated respectively. TiO2 calcined at 550℃ showed the best catalytic activity. In the presence of TiO2 calcined at 550℃ , about 56.57% of nitrobenzene in the solution could be ozonated. Both ozone dosage and initial concentration of nitrobenzene exerted a positive influence on the catalytic ozonation. But the increase of the catalyst mass did not yield any significant increase of the nitrobenzene removal. The efficiency of catalytic ozonation was special lower at acid pH than basic pH. It was also observed that both ozonation and catalytic ozonation were significantly influenced by tert-butyl alcohol, which testified that nanosized TiO2 catalyzed ozonation of nitrohenzene follows a radicaltype mechanism.