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研究报告

Dissolution kinetics of heavy metals in electroplating sludge and their fate in soil

摘要：电镀污泥是电镀工业中重金属的"汇"，在降水的作用下可能向环境释放大量的重金属.本文通过连续浸出实验和动力学拟合探究了电镀污泥中重金属的溶出特性，并分析了重金属在土壤中的吸附、迁移转化及淋出行为.结果表明，在淋溶初期，重金属从电镀污泥中大量释放，且土壤中Cr （Ⅵ）、Ni的淋出浓度分别高达0.102、0.222 mg·L^-1.淋溶后，表层土壤中Ni、Cu的总量及可交换态/碳酸盐结合态含量均显著增加；由于专性吸附作用，Cu的铁锰氧化物结合态含量也大量增加，Cu在土壤中的吸附率高达89.32%~97.67%，降低了其从土壤中的淋出风险.Cr、Ni、Cu更易在红壤中发生吸附并转化为稳定的有机结合态，降低了重金属的潜在迁移性；相应地，电镀污泥中释放的Cr、Ni、Cu在栗钙土中具有较高的淋出风险.

Abstract：Electroplating sludge is the sink of heavy metals from the electroplating industry, which might be the source of heavy metals to the environment due to the inadequate disposal process of the sludge, and thus causing the secondary contamination to the soils and ground water. Leaching experiment were conducted to study the dynamic characteristics of heavy metals from electroplating sludge, and their adsorption, migration, transformation of heavy metals in soils were discussed. The results obtained showed that large quantities of heavy metals were released from the electroplating sludge at the initial leaching stage, the leaching concentrations of Cr(Ⅵ) and Ni from the soil reached as high as 0.102 mg·L^-1 and 0.222 mg·L^-1. The total amount and the exchangeable/carbonate fraction of Ni and Cu increased significantly in the surface soil after leaching. The reducible fraction of Cu increased greatly as well due to the specific adsorption, with the adsorption rate of Cu in the soil reached 89.32%~97.67%, which might reduce the leaching risk of Cu from the soil. Cr, Ni and Cu were better adsorbed and converted into oxidizable fraction in red soil, which could reduce the potential migration of heavy metals, indicating a higher leaching risk of Cr, Ni, and Cu in chestnut soil.