MgO/PAL活化过一硫酸盐联合修复草甘膦镉共污染农田土壤

Remediation of Glyphosate-Cd Co-Contaminated Farmland Soil by Modified Palygorskite Combined with Peroxymonosulfate(PMS)

利用坡缕石(RPAL)并采用共沉淀法制备了MgO/PAL复合材料,该材料活化过一硫酸盐(PMS)可对草甘膦和镉(Cd)共污染的土壤进行有效修复.考察了不同镁盐剂量对MgO/PAL复合材料吸附Cd性能的影响,揭示了MgO/PAL复合材料结构形貌与吸附性能之间的构效关系.结果表明:当镁盐剂量为30 mL时,MgO在RPAL纳米棒表面均匀分布,比表面积为28.838 m^2·g^-1,MgO/PAL对Cd2+的吸附量为187.05 mg·g^-1.Zeta结果表明,随着镁盐剂量的增加,坡缕石表面由负电势向正电势转变,原位生成Cd(OH)2沉淀是MgO/PAL复合材料钝化Cd的主要机制.经MgO/PAL和PMS处理后,初始质量分数为10 mg·kg^-1 Cd污染土壤中Cd的浸出质量分数为0.93 mg·kg^-1,达到TCLP国际标准,草甘膦的去除率为73.81%.

The MgO/PAL composite material was prepared by co-precipitation method using palygorskite(RPAL),which can activate persulfate(PMS)to jointly repair glyphosate and cadmium(Cd)contaminated soil.The effects of different magnesium salt dosages on the Cd adsorption performance of MgO/PAL composites were studied,and the structure-effect mechanism relationship between morphology structure and adsorption performance of MgO/PAL composites was revealed.The experimental results suggest that when the magnesium salt was 30 mL,the adsorption capacity of MgO/PAL for Cd2+was 187.05 mg·g^-1.MgO was evenly distributed on the surface of RPAL Nanorods with the specific surface area of 28.838 m^2·g^-1.With the increase of the amount of magnesium salt,the surface of the attapulgite changed from negative potential to positive potential,thus the in situ Cd(OH)2 precipitation was the critical mechanism of passivation of Cd on the surface of MgO/PAL composite materials.After the 10 mg·kg^-1 Cd contaminated soil was treated by MgO/PAL+PMS,the leaching concentration of Cd was 0.93 mg·kg^-1,which reached the TCLP international standard and the removal rate of glyphosate was 73.81%.