纳米Fe_3O_4/CeO_2-H_2O_2非均相类Fenton体系对3,4-二氯三氟甲苯的降解

Degradation of 3,4-Dichlorobenzotrifluoride by Fe_3O_4/CeO_2-H_2O_2 Heterogeneous Fenton-Like Systems

以浸渍法制备的新型纳米Fe3O4/Ce O2为催化剂,3,4-二氯三氟甲苯(3,4-DCBTE)为目标污染物,在Fe3O4/Ce O2-H2O2非均相类Fenton体系中对目标污染物的降解进行研究,考察催化剂的催化效果和温度、p H、H2O2投加量等因素对催化剂催化效果的影响.结果表明,以纳米Fe3O4/Ce O2作为催化剂的非均相类Fenton体系对3,4-二氯三氟甲苯的处理效果极佳;随着温度的升高,纳米Fe3O4/Ce O2的催化效果不断提高;在偏酸性环境中,p H越低催化效果越好,p H=2时反应去除效率可达96.67%;随着H2O2投加量的增加,3,4-二氯三氟甲苯的降解效率先提高后降低,投加量为15 mg·L-1时去除效果最好可达99.47%;随着催化剂投加量的增加,同样出现了处理效果先升高后降低的现象,投加量为0.5 g·L-1时催化效果最好可达99.64%.在以纳米Fe3O4/Ce O2为催化剂的非均相类Fenton体系中,3,4-二氯三氟甲苯的降解符合一级反应动力学,反应所需活化能较低只需30.26 k J·mol-1.

The 3,4-Dichlorobenzotrifluoride( 3,4-DCBTE) was dehalogenated with oxidation treatment by heterogeneous Fenton-like system,using nanoscale Fe3O4/CeO2 as a catalyst. This nanoscale catalyst was prepared by the impregnated method. As a highly active new heterogeneous Fenton-like catalyst,nanoscale Fe3O4/ CeO2 not only has the characteristics of the traditional Fenton-like catalyst but also can prevent the secondary pollution which caused by Fe2 +. To find the optimum catalytic conditions for nanoscale Fe3O4/ CeO2,the influence factors were investigated. The results indicated that the degradation ratio of 3,4-DCBTE was significantly improved by adding nanoscale Fe3O4/ CeO2,with the removal ratio reaching 97. 76% in 120 minutes and 79. 85% in 20 minutes. As the temperature increasing,the catalytic effect of nanoscale Fe3O4/CeO2 catalyst had been constantly improved obviously. As the p H decreased,the degradation ratio of 3,4-DCBTE increased. With the increase of dosage of hydrogen peroxide( H2O2),the degradation efficiency of 3,4-DCBTE initially increased and then decreased,because oxygen(O2) was generated in preferential self-reaction when an excess of(H2O2) was added. The optimum removal efficiency was observed with the dosage of 15 mg·L- 1. With the increased amount of catalyst,there was a same trend as dosage of hydrogen peroxide(H2O2). The degradation ratio of 3,4-DCBTE initially increased and then decreased,the optimum amount of catalyst was 0. 5 g·L- 1. The results also suggested that the reaction process followed the first-order kinetics and the thermodynamic analysis demonstrated that the reaction was only needed low reaction activation energy.