靛蓝的媒质间接电化学还原及其动力学

Mediator Indirect Eelectrochemical Reduction of Indigo and Its Kinetics

研究了以 Fe_2(SO_4)_3/三乙醇胺(TEA)/NaOH 为媒质体系间接电化学还原靛蓝的工艺条件及动力学。采用循环伏安法(CV)确定络合体系的还原电位为-0.9 V(相对氧化汞电极)。采用恒流法还原靛蓝,以在线光谱仪监测反应过程中靛蓝转化率随时间的变化来考察反应条件对还原的影响。结果表明,当还原靛蓝浓度为0.02 g/L 时,合适的反应条件为电流密度3 mA/cm^2,Fe_2(SO_4)_3浓度0.0040 mol/L,50℃,pH 值14.0,TEA 浓度0.150 mol/L。当满足一定的电流密度和媒质浓度时,靛蓝还原由其颗粒表面溶解速率决定,其活化能为26.1 kJ/mol。

The conditions and kinetics of indigo reduced by indirect electrochemical reduction using Fe2 （SO4）3/triethanolamine （TEA）/NaOH as mediator were investigated. The reduction potential of the mediator was determined by cyclic voltammetry （CV） and it was found that the reduction potential was -0.9 V. The effects of reaction conditions on the reduction of indigo by Chronopotentiometry were studied by monitoring using spectrometer on-line for quantitative analysis. The results showed that the optimum conditions were current density 3 mA/cm^2, concentration of Fe2（SO4）3 0. 004 0 mol/L, 50 ℃, pH14.0, TEA 0. 150 mol/L. The reduction of indigo was determined by surface dissolution rate when the current density and concentration of mediator reached some certain values and the activation energy was 26.1 kJ/mol.