化学淋洗联合电动技术修复重金属污染土壤的效果及其机制

采用化学淋洗与电动技术联合修复重金属污染土壤,以明确其效果及其机制.试验选择了5种化学淋洗剂FeCl₃、 Fe(NO₃)₃、 KCl、 KNO₃和HCl溶液,分析比较Fe³⁺、 K⁺、 H⁺和Cl^-对土壤中4种重金属(Cd、 Pb、 Cu和Zn)的去除效果,其后,对化学淋洗后的土壤进行垂直电动修复,研究化学淋洗对重金属污染土壤电动修复去除效率的影响.结果表明,Fe³⁺、 K⁺、 H⁺和Cl^-对土壤中4种重金属的淋洗效果不同,对于Cd和Zn, H⁺去除效果最好,对于Pb和Cu, Fe³⁺去除效果最好.整体上比较,对于土壤中Cd、 Pb和Cu的去除,化学淋洗剂FeCl₃和Fe(NO₃)₃去除效果最好.对于土壤中Zn的去除,...

Effectiveness and Mechanisms of Chemical Leaching Combined with Electrokinetic Technology on the Remediation of Heavy Metal Contaminated Soil

In this study, chemical leaching and electrokinetic technology were used to remediate heavy metal contaminated soil to elucidate its effectiveness and mechanisms. Chemical leaching agents of FeCl₃, Fe(NO₃)₃, KCl, KNO₃, and HCl solutions were selected, and the effects of Fe³⁺, K⁺, H⁺, and Cl^- on four heavy metal (Cd, Pb, Cu, and Zn) removals were compared and analyzed. Then, the influence of the speciation of heavy metals in soil after chemical leaching on the electrokinetic remediation efficiency was studied. The results showed that Fe³⁺, K⁺, H⁺, and Cl^- had different effects on the four heavy metal removals; for Cd and Zn, the removal effect of H⁺was the most effective, but for Pb and Cu, the effect of Fe³⁺ was the most obvious. On the whole, FeCl₃ and Fe(NO₃)₃ showed the best removal effect for Cd, Pb, and Cu. For the removal of Zn from the soil, the difference in the removal effect of the five leaching agents was not obvious. In comparison with that of FeCl₃ and Fe(NO₃)₃, the HCl solution had a moderate removal effect on the four heavy metals in the soil, and the neutral salts KCl and KNO₃ had little removal effect on the four heavy metals. Especially for Cd and Cu, KCl and KNO₃ addition significantly increased the removal of heavy metals through the subsequent electrokinetic remediation. After the chemical leaching, electrokinetic remediation could make heavy metals in the topsoil (0-10 cm) migrate downward and enrich the 10-20 cm and 20-30 cm soil layers, which requires further studies to resolve.