阴离子交换膜辅助电解还原法处理含镉废水:原理及优化

Anion exchange membrane-assisting electrochemical reduction treatment on Cd-containing wastewater:Principle and optimization

本文研究了阴离子交换膜(AEM)辅助电解还原法处理含镉废水.通过对比电解还原过程中是否采用AEM膜对溶液pH、电解电压、除镉率和能耗变化的影响,阐明电解还原法除镉的化学原理,找出限制除镉效率的原因,提出了优化方案.研究发现,H+的扩散是除镉效率的主要限制因素,研究中进一步采用阴离子交换膜,利用其对离子的选择透过性,限制了阳极室生成的H+向阴极室的扩散,抑制了含镉废液pH的下降,减弱了析氢效应及对电解生成金属镉的酸腐蚀,明显提高了电解还原除镉的效率.废液中Cd^(2+)浓度从33.6 g·L^(−1)降低到1.06 mg·L^(−1),镉去除率达99.99%,电荷效率98%,消耗电能为270 Wh·L^(−1).

This article studies the treatment on cadmium-containing wastewater by anion exchange membrane(AEM)-assisting electrolytic reduction.By comparing the influence of AEM membrane on the changing trends of the solution pH,voltage,cadmium removal rate and energy consumption during the electrolysis,the chemical principle for the electrolysis was revealed,the reasons of limiting cadmium removal efficiency were found,the electrolysis reduction process was optimized.The research found that the diffusion of H+is the main limiting factor for the cadmium removal efficiency.In the research,the anion exchange membrane was further used,by utilizing its selective permeability to ions to limit the diffusion of H+generated in the anode compartment to the cathode compartment.The reduction of pH of cadmium waste liquid was inhibited,the hydrogen evolution reaction and acid etching of the electrolytic metal cadmium were weakened,significantly improve the efficiency of electrolytic reduction to remove cadmium.The residual Cd^(2+)concentration after treatment is reduced from 200 mg·L^(−1) to 1.06 mg·L^(−1),the cadmium removal rate reaches to 99.99%,the charge efficiency 98%,and the power consumption is 270 Wh·L^(−1).