磁性黏土颗粒对污染土壤中镉去除作用的初步研究

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

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污染土试验表明,材料最佳施用量为MSAZ与土壤质量比1︰5,此时在人工模拟污染红壤中0.43 mol/L HNO_(3)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污染水稻土的去除试验表明,MSAZ对这两种土壤中0.43 mol/L HNO_(3)提取态Cd的首次施用去除率均约40%;经过5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。

A millimeter-level magnetic clay particle adsorption material recorded as MSAZ was used to test its soil Cd removal efficiency.For different simulated Cd-contaminated soils,the results showed that the optimal mass ratio of MSAZ:soil was 1︰5.With this application ratio,the removal rate of 0.43 mol/L HNO_(3) extracted Cd in the simulated red soil was as high as 95% in a single application,and the removal rates could also reach 75%—80% in the brown and black soils.For dryland soils with high Cd background values and Cd-contaminated paddy soils,the results showed that the removal rate of 0.43 mol/L HNO_(3) extracted Cd by MSAZ was about 40% from the two soils in a single application.After five times of repeated use,the cumulative removal rate of 0.43 mol/L HNO_(3) extracted Cd on MSAZ reached 98% from the actual Cd-contaminated paddy soil.The MSAZ still maintained 85% adsorption capacity,and its recovery rate was higher than 80% after five reusing cycles.The magnetic clay particles tested in this study has excellent soil Cd removal performance and showed potential application prospect,which can provide materials and technical supports for subsequent in-situ treatment of Cd pollution in farmland soil.