磁性黏土颗粒对污染土壤中镉去除作用的初步研究

农田土壤中镉（Cd）污染备受关注，亟需开发出可以在土壤中快速去除Cd的修复材料与方法。磁性黏土矿物吸附材料因具有重金属吸附容量高和便于回收再利用等特点已成为当前土壤修复净化方面的研究热点。本研究使用了一种毫米级磁性黏土颗粒吸附材料测试其对土壤Cd的去除性能，材料记为巯基改性凹凸棒@沸石（MSAZ）。通过对不同类型人工模拟Cd污染土实验表明，材料最佳施用量为MSAZ:土壤质量比1:5，此时在人工模拟污染红壤中0.43 mol/L HNO3提取态Cd的单次材料施用去除率高达95%，在人工模拟的棕壤和黑土也可达75%-80%。通过对实际的Cd高背景旱地土壤和Cd污染水稻土的去除实验表明，MSAZ对这两种土壤中0.43 mol/L HNO3提取态Cd的首次施用去除率均约40%；经过五次重复利用后，MSZA对污染水稻土中0.43 mol/L HNO3提取态Cd的累积去除率可达98%，并且该材料依然保持着85%的吸附能力，回收率仍高于80%。本研究的磁性黏土颗粒具有较强的土壤Cd去除性能和应用潜力，可为农田土壤Cd污染的原位修复提供材料及技术支持。

Preliminary Study on Removal of Cadmium from Contaminated Soil by Magnetic Clay Particles

Cadmium (Cd) pollution in farmland soil has attracted much attention. It is urgent to develop functional remediation materials and repair methods that can quickly remove Cd from the soil. Magnetic clay mineral adsorbent has become a research hotspot because of its high heavy metal adsorption capacity and easy recycling. This study used a millimeter-level magnetic clay particle adsorption material recorded as MSAZ to test its soil Cd removal efficiency. For different types of artificially simulated Cd contaminated soils, the results show that the optimal mass ratio of MSAZ:soil is 1:5. With this application ratio, the removal rate of 0.43 mol/L HNO3 extracted Cd in the artificially simulated red soil is as high as 95% in a single application, and the removal rates can also reach 75%-80% in the brown soil and black soil. For dryland soils with high Cd background values and Cd contaminated paddy soils, the results show that the removal rate of 0.43 mol/L HNO3 extracted Cd by MSAZ from the two soils is about 40% in a single application. After five times of repeated use, the cumulative removal rate of 0.43 mol/L HNO3 extracted Cd on the MSAZ reach 98% from the actual Cd-contaminated paddy soil. The MSAZ still maintains 85% adsorption capacity, and its recovery rate is higher than 80% after five reusing cycles. The magnetic clay particles tested in this study has excellent soil Cd removal performance and show potential application prospect, providing materials and technical supports for subsequent in-situ treatment of Cd pollution in farmland soil.