碳纳米管负载纳米四氧化三铁多相类芬顿降解亚甲基蓝

Degradation of methylene blue by heterogeneous Fenton-like reaction using Fe_3O_4/carbon nanotube composites

在课题组前期研究的基础上,以碳纳米管(MWCNTs)为载体制备了Fe3O4/MWCNTs复合物并作为催化剂,以染料亚甲基蓝(MB)为降解对象,研究了该催化剂催化H2O2对亚甲基蓝溶液的降解特性及其影响因素,并考察了催化剂的重复使用效果,探讨了催化反应的机理.结果表明,在pH值3~8的范围内,催化反应体系都能有效降解MB,最佳pH值为3.5.随着催化剂投量的增加,MB的降解率明显提高,500 mg·L-1催化剂投量条件下,MB的降解率最高.随着H2O2初始浓度的增加,MB的降解率增加,10 mmol·L-1时MB的降解率最高.溶液中共存的阴离子会降低MB的降解率.在最佳条件,即温度25℃、H2O2浓度10 mmol·L-1、催化剂浓度500 mg·L-1的条件下,0.20 mmol·L-1MB在30 min内的降解率达到99.1%.催化剂重复使用后仍然具有较好的催化活性,说明Fe3O4在MWCNTs表面负载比较牢固,催化剂具有反复使用的能力.催化反应机理是催化剂催化H2O2产生羟基自由基,高活性的羟基自由基氧化MB.

In order to enhance the catalytic activity of the heterogeneous Fenton-like reaction,the catalyst of Fe3O4/MWCNTs composites was synthesized based upon previous findings of our research group. The Fe3O4/MWCNTs was used as catalyst of the heterogeneous Fenton-like reaction to degrade methylene blue( MB) in aqueous solution. The influencing factors,possible mechanism of the reaction,and the reusability of the catalyst were investigated. The results showed that the MB was effectively degraded at pH 3 ~ 8. The maximum degradation was at pH 3. 5. The removal efficiency of MB increased with the increase of the initial H2O2concentration and reached maximum when the H2O2concentration was 10 mmol·L-1. The degradation efficiency of MB increased with the catalyst concentration and reached maximum when the catalyst concentration was 500 mg·L-1. The coexisted anions decreased the degradation efficiency of MB. Under the optimized conditions which were,500 mg·L-1composite catalyst,pH = 3. 5,10. 0 mmol·L-1of H2O2and 25 ℃,the degradation efficiency of MB( 0. 20 mmol·L-1) reached99.1% within30 min reaction. Repeated uses of catalyst did not decreaseobviously the degradation efficiency of MB. The catalytic mechanism was that Fe3O4/MWCNTs could catalytically decompose H2O2to produce hydroxyl free radical to oxidized MB.