School of Environmental and Materials Engineering, Shanghai Polytechnic University, Shanghai, 201209, China.
Shanghai Collaborative Innovation Centre for WEEE Recycling, Shanghai Polytechnic University, Shanghai, 201209, China.
Chemosphere. 2020 May;247:125963. doi: 10.1016/j.chemosphere.2020.125963. Epub 2020 Jan 20.
Lead (Pb) pollution in the soil is becoming more and more serious, and lead poisoning incidents also constantly occur. Therefore, the remediation of lead pollution in the soil has attracted widespread attention. In this study, heavy metal lead in soil was remediated by mechanochemical methods. The effects of different ball milling conditions on the toxic leaching concentration and morphological distribution (BCR sequential extraction procedure) of lead in contaminated soil were analyzed, including the addition of calcium dihydrogen phosphate (Ca(HPO)), ball milling time, and ball milling speed. The reaction mechanism was analyzed by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and a laser particle size analyzer. The results show that the optimal conditions for mechanochemical immobilization were 10% additive (Ca(HPO)), milling speed of 550 rpm, and ball milling time for 2 h. Under this condition, the toxic leaching concentration of lead from contaminated soil was 4.36 mg L, and in the BCR sequential extraction procedure, Pb was mainly present in the residual fraction (54.96%). The mechanism of mechanochemical solidification of heavy metal lead in soil is that, during the ball milling process, the lead precipitates with Ca(HPO) to produce dense agglomerates (Pb(PO) and PbCa(PO)(OH)), which fixes the lead in the soil and hampers its leaching.
土壤中的铅污染越来越严重，铅中毒事件也时有发生。因此，土壤中铅污染的修复引起了广泛关注。本研究采用机械化学方法修复土壤中的重金属铅。分析了不同球磨条件对污染土壤中铅的毒性浸出浓度和形态分布（BCR 顺序提取程序）的影响，包括添加磷酸二氢钙（Ca(HPO)）、球磨时间和球磨速度。通过 X 射线衍射（XRD）、扫描电子显微镜（SEM）和激光粒度分析仪分析了反应机理。结果表明，机械化学固定化的最佳条件为 10%添加剂（Ca(HPO)）、研磨速度 550 rpm 和研磨时间 2 h。在此条件下，污染土壤中铅的毒性浸出浓度为 4.36 mg/L，在 BCR 顺序提取程序中，Pb 主要存在于残渣（54.96%）中。土壤中重金属铅的机械化学固化机制是，在球磨过程中，铅与 Ca(HPO)沉淀生成致密的团聚体（Pb(PO)和 PbCa(PO)(OH)），从而固定土壤中的铅，阻止其浸出。
