铁-三乙醇胺(Fe-TEA)可作为媒质用于间接电化学法还原靛蓝.本工作采用循环伏安法研究了靛蓝在Fe-TEA媒质中的电化学行为,比较了石墨、银、镍、不锈钢四种阴极材料的电催化性能,探讨了靛蓝间接电还原的机理.此外,还进行了一组L9(3^4)正交电解实验,通过正交实验分析了各因素对电流效率的影响.实验结果表明:在Fe(III)-TEA媒质中,以不锈钢网为阴极可实现靛蓝的间接电化学还原,最高电流效率可达44.7%.在实验所设计因素水平范围内,对电流效率影响最大的因素为Fe(III)-TEA媒质浓度.在靛蓝的间接电还原过程中存在一种靛蓝自由基,该自由基能起到靛蓝电还原的媒质作用,在一定实验条件下,该靛蓝自由基的媒质作用可以大于Fe(III)-TEA.
Fe-triethonolamine (Fe-TEA) complexes as mediator are well suitable for the indirect reduction of indigo.In our work,the reduction of indigo was investigated in a Fe-TEA system by cyclic voltammetry (CV).The electrocatalytic performance of four kinds of cathode materials (graphite,silver,nickel,and stainless steel) for the reduction of Fe(III)TEA was compared.Further experiments were carried out to compare the effects of operating parameters including temperature,current,concentrations of NaOH and Fe(III)-TEA.Experimental results showed that this new route was feasible for the production of water-soluble indigo.A high current efficiency (44.7%) was achieved using optimized conditions and the concentration of the Fe(III)-TEA mediator was found to be the main influence.A new indigo radical mediator was formed during electrolysis and under certain condition,the effect of this indigo radical on the current efficiency was larger than that of Fe(III)-TEA.