脉冲电压强化类芬顿氧化Cu-EDTA破络与Cu阴极回收研究

Enhanced decomplexation of Cu-EDTA and cathode recovery of Cu by the Fenton-like oxidation using pulsed potential

工业废水中的重金属常与共存有机配体结合形成重金属-有机络合物,其化学稳定性高,传统水处理技术难以实现重金属络合物的有效去除.电化学技术可以通过电氧化与电还原同步实现重金属络合物破络与阴极回收金属.本研究针对单阴极无法同步产H_(2)O_(2)与回收重金属的问题,构建了碳气凝胶(CA)和Ti组成的双阴极类芬顿体系,研究了阴极脉冲电压方式对典型重金属络合物Cu-EDTA破络合与定向回收Cu的影响机制.同时,分别比较了在CA阴极和Ti阴极上施加方波脉冲、三角脉冲和差分脉冲电压对双阴极体系原位电产H_(2)O_(2)、Cu-EDTA氧化破络合和Cu定向回收的影响.结果表明,在CA阴极施加方波脉冲电压效果最优,脉冲宽度为5 s时H_(2)O_(2)的产量在反应60 min达到22.5 mg·L^(-1),相比恒定电位提升了80.57%,Cu-EDTA去除率在180 min达到88.63%,提升了16.83%.Ti阴极施加三角脉冲电压效果最佳,脉冲宽度为10 s时Ti和CA阴极回收Cu的比值为7.91,相比恒定电位提升了68.54%.CA阴极施加方波脉冲电压可以降低46.34%的能耗,Ti阴极施加三角脉冲电压可以降低21.95%的能耗.研究结果可为电化学强化废水中重金属络合物去除和重金属定向回收提供科学依据.

Heavy metals in industrial wastewater are often complexed with co-existing organic ligands to form heavy metal-organic complexes,which are highly chemically stable and are difficult to be removed by the traditional water treatment technologies.The electrochemical technology can realize the decomplexation of heavy metal complexes and cathodic metal recovery simultaneously through electrooxidation and electroreduction.In this study,a dual-cathode Fenton-like system composed of carbon aerogels(CA)and Ti plate was established,aiming to solve the problem that single cathode can not simultaneously produce H_(2)O_(2) and recover heavy metals.The mechanism of different cathodic pulse voltage mode on decomplexation of typical heavy metal complex Cu-EDTA and directional recovery of Cu was investigated.The effect of square wave pulse,triangular pulse,and differential pulse voltage applied to CA and Ti cathode on the production of H_(2)O_(2),oxidative decomplexation of Cu-EDTA,and directional recovery of Cu were compared,respectively.The results indicated that the application of square wave pulse voltage to CA cathode had the best efficiency.When the pulse width was 5 s,the yield of H_(2)O_(2) reached 22.5 mg·L^(-1) in 60 min,and the removal rate of Cu-EDTA reached 88.63%in 180 min,which were increased by 80.57%and 16.83%compared with those at the constant potential,respectively.For the Ti cathode,the triangular pulse voltage had the best efficiency.When the pulse width was 10 s,the ratio of Cu recovery on Ti to that on CA was 7.91,which was increases by 68.54%compared with the constant potential.The energy consumption can be reduced by 46.34%when the square wave pulse voltage was applied to CA cathode,and reduced by 21.95%when the triangle pulse voltage was applied to Ti cathode.These results can provide a scientific basis for the enhanced removal of heavy metal complexes and directed recovery of heavy metals in wastewater by electrochemical method.