电镀厂污染土壤重金属形态及淋洗去除效果

摘要

Soil samples were collected from a heavily polluted area of an electroplating plant site for analysis of totals of the heavy metals therein and contents of their various forms separately in the soil. Furthermore, researches and screening were done to develop high-efficiency soil washing agents, of which comparison was made in effect of heavy mental removal rate. Results show that chromium ( Cr) and nickel (Ni) were the most abundant heavy metals in the soil, reaching 1 564. 00 and 679. 00 mg ? Kg respectively in total, and copper ( Cu) , zinc ( Zn) , and lead ( Pb) was found to be 297.00, 276.00 and 51. 40 mg- kg-1, respectively, of which 13. 16%, 28.08%, 41.77%, 21.50% and 31. 18% was in available form, respectively. Among the six washing agents, I. E. Deionized water, hydrochloric acid, acetic acid, oxalic acid, citric acid and EDTA, deionized water was less effective in removing the 5 heavy metals while oxalic acid was more effective in removing Cu, Cr, Ni and Zn, reaching 55. 1% , 24. 8% , 47. 5% and 29. 3% in removing rate, citric acid was better at removing Cu, Cr, Ni and Zn, reaching 26. 3% , 25. 7% , 33. 0% and 21. 6% ;and EDTA showed better performance on Cu, Ni, Zn and Pb, with removal rate being 31. 5% , 28. 9% , 21. 4% and 30. 6% , respectively. Taking into account comprehensively extraction effectiveness, water-solubility, easiness in operation and cost of the agents, it is suggested that citric acid be used with the optimal liquid to soil ratio being 10 : 1 and the optimal duration of washing being 6 hours.%以某电镀厂污染场地重污染区域土壤为研究对象,对土壤中重金属全量和各形态含量进行分析,并研究筛选高效土壤淋洗剂,比较其淋洗去除效果.结果表明,该土壤以铬和镍污染最为严重,土壤铬和镍含量分别达1 564.00和679.00 mg·kg -1,土壤铜、锌和铅含量分别为297.00、276.00和51.40mg·kg-1,铜、铬、镍、锌和铅的有效态比例分别为41.77％、13.6％、28.08％、21.50％和31.18％.去离子水、盐酸、乙酸、草酸、柠檬酸和EDTA 6种淋洗剂中,去离子水对5种重金属提取量均较少；草酸对铜、铬、镍和锌去除效果较好,去除率分别为55.1％、24.8％、47.5％和29.3％；柠檬酸对铜、铬、镍和锌去除效果较好,去除率分别为26.3％、25.7％、33.0％和21.6％；EDTA对铜、镍、锌和铅去除效果较好,去除率分别为31.5％、28.9％、21.4％和30.6％.综合考虑淋洗剂的提取效果、水溶性以及操作难度和成本,建议采用柠檬酸作为淋洗剂,最佳液土比[V(液)∶m(土)]为10∶1,最佳淋洗时间为6h.