磷酸二氢钙淋洗修复矿区周边镉污染土壤

以磷酸二氢钙（Ca(H2PO4)2）为原料配制淋洗剂，对某矿区周边镉（Cd）污染土壤进行淋洗修复。分析了不同配制条件下淋洗剂中Ca2+、总磷含量及其对Cd污染土壤的淋洗效果，并在此基础上进一步分析了液固比、淋洗时间对修复效果的影响。对淋洗过程进行动力学分析，分析了淋洗前后土壤Cd形态分布。结果表明：淋洗剂中Ca2+、总磷含量与Ca(H2PO4)2投加量呈正相关，且未加热条件下配制的淋洗剂中Ca2+、总磷含量、pH更高。采用投加量为0.07 mol的Ca(H2PO4)2与去离子水混合加热配制的淋洗剂，在液固比5、淋洗时间3 h的条件下，淋洗效果最优，土壤Cd去除率高达70.83%。Elovich方程可以较好地拟合淋洗过程，解吸过程为非均相扩散过程。淋洗后，弱酸提取态及可还原态Cd得到有效去除。淋洗修复方法可行，为去除土壤中的Cd提供新思路。

Study on Remediation of Cadmium Contaminated Soil Around Mining Area by Elution with Monocalcium Phosphate

Elution experiment of Cd contaminated soil around a mine was carried out using Ca(H2PO4)2 as raw material to prepare leaching agent. The contents of Ca2+ and total phosphorus in eluant and elution effect under different preparation conditions were analyzed. Based on that, the effects of L/S and washing time on remediation effect were further analyzed. The washing process was fitted dynamically, and the morphological distributions of Cd in soil before and after elution were analyzed. The results show that contents of Ca2+ and total phosphorus in eluant are positively correlated with dosage of Ca(H2PO4)2, and the contents of Ca2+ and total phosphorus and pH value of eluantt prepared without heating are higher. The elution effect is the best when the eluant prepared by mixing 0.07mol of Ca(H2PO4)2 with deionized water for heating, tL/S is 5, and elution time is 3 hours. The removal rate of Cd in soil can reach 70.83%. Elovich equation fits the kinetic process well, and the desorption process is heterogeneous diffusion process. After elution, the extracted form of weak acid and reducible Cd can be effectively removed. Elution remediation method is feasible and can provide a new idea for removing Cd from soil