碳纳米管修饰电极电催化还原去除废水中的氯霉素

为发展废水中抗生素的处理技术、保护水环境质量,采用表面活性剂辅助分散碳纳米管,制备碳纳米管修饰电极,研究了修饰电极对氯霉素的电催化还原能力和动力学特征,初步探讨了氯霉素的还原去除机制.结果表明,双十六烷基磷酸(DHP)可以有效分散碳纳米管,通过优化碳纳米管和DHP的配比、分散液修饰量,制备的碳纳米管修饰电极还原2 mg·L~(-1)氯霉素24 h时的去除率达到97.21%;电催化还原氯霉素的动力学过程符合一级反应动力学模型,去除速率常数为0.157 4 h~(-1),半衰期为4.40 h.采用液相色谱-串联质谱分析法(LC-MS/MS)鉴定了氯霉素的还原产物,分析了氯霉素还原的可能途径,电催化不仅还原了氯霉素中的硝基,还可以进一步还原羰基和脱氯,显著降低氯霉素的毒性.

Removal of Chloramphenicol in Wastewater by Electrocatalytic Reduction with Carbon Nanotubes-Modified Electrode

In order to develop treatment technique for antibiotics and protect water environmental quality, the carbon nanotubes (CNTs) modified electrode was prepared with surfactant-assisted dispersion, the electrocatalytic reduction ability and kinetic characteristics of chloramphenicol were studied using the modified electrode, and the reduction mechanism was investigated preliminarily. The results showed that CNTs could be effectively dispersed by dihexadecyl phosphate (DHP), and the removal rate of 2 mg·L^-1 chloramphenicol reached 97.21% after 24 h reduction using the modified electrode under the optimal ratio of CNTs to DHP and the modified amount of CNTs dispersion. The kinetic process of the electrocatalytic reduction could be well described by the first-order reaction kinetic model, and the removal rate constant and half-time were 0.1574 h^-1 and 4.40 h, respectively. The reduction products were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to reveal the possible reduction pathway, which indicated that the electrocatalysis could not only reduce nitro-group in chloramphenicol, but also further reduce carboxyl group and dechlorination, and thus significantly decrease its toxicity.