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(H2PO4)2), 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(H2PO4)2), 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-1, 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(H2PO4)2 to produce dense agglomerates (Pb3(PO4)2 and PbxCa10-x(PO4)6(OH)2), which fixes the lead in the soil and hampers its leaching.

中文翻译：

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用Ca（H2PO4）2的球磨机对铅污染的土壤进行机械化学固定。

土壤中的铅（Pb）污染越来越严重，铅中毒事件也不断发生。因此，土壤中铅污染的修复引起了广泛关注。在这项研究中，通过机械化学方法修复了土壤中的重金属铅。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（H2PO4）2），球磨时间和球铣削速度。通过X射线衍射法（XRD），扫描电子显微镜（SEM）和激光粒度分析仪分析反应机理。结果表明，机械化学固定的最佳条件是添加10％的添加剂（Ca（H2PO4）2），铣削速度为550 rpm，球磨时间为2 h。在这种条件下，从污染土壤中铅的有毒浸出浓度为4.36 mg L-1，在BCR连续萃取过程中，残留部分中主要存在Pb（54.96％）。重金属铅在土壤中的机械化学固化机理是，在球磨过程中，铅与Ca（H2PO4）2沉淀，产生致密的附聚物（Pb3（PO4）2和PbxCa10-x（PO4）6（OH） 2），将铅固定在土壤中并阻碍其浸出。