不同的增强试剂对重金属污染场地土壤的电动修复影响

Electrokinetic remediation of an electroplating contaminated soil with different enhancing electrolytes

选择重金属污染场地土壤为修复对象,研究了添加络合剂EDTA?有机酸乳酸和柠檬酸以及无机酸硝酸对电动修复该污染土壤的影响.结果表明,增强试剂的加入,显著促进了铜?铅?镍和六价铬在电场中的迁移和去除,电动过程促进了土壤重金属向有效态(醋酸铵提取)转化.其中,在阴极加入乳酸并控制p H3.5的处理,土壤中铜的去除率最高,达78.7%.在阴?阳极都加入EDTA的处理中,土壤中重金属的去除率在30%左右,重金属在靠近阴极的部分发生聚集.在阴极加入柠檬酸的处理中,土壤中铜?镍和六价铬的去除率均较高,分别为68.5%?53.3%和52.9%.阴极加入硝酸控制p H3.5对土壤中六价铬的去除率最高,达93.3%.

Effect of addition of complex, organic and inorganic acid （EDTA, lactic acid, citric acid and nitric acid） in catholyte on the electrokinetic remediation （EK） of an electroplating contaminated soil with heavy metals was studied in laboratory-scale experiments. The addition of enhancement agents significantly enhanced the migration and removal of Cu, Pb, Ni and Cr^6＋ in soil and EK process favored the heavy metals transferring into exchangeable species. The addition of lactic acid in the catholyte resulted in the highest Cu removal as high as 78.7%. Adding EDTA in the anolyte/catholyte during the electrokinetic treatment, the removal efficiency of heavy metals was about 30% and most of heavy metals were accumulated in the soil column section near the cathode. Citric acid was effective for the removal of Cu, Ni and Cr^6＋ from soil and in which the removal rates were 68.5%, 53.3% and 52.9%, respectively. Nitrate was the most effective reagent for Cr^6＋ with a removal rate of 93.3%.