FeAl-LDHs/生物炭修复镉污染土壤及作用机制  

Remediation of Cadmium Contaminated Soils by FeAl-LDHs/Biochar and Its Mechanism

作　　者：曹青青 宋敏[1] 孟凡跃 赵炎 宋兵 CAO Qingqing;SONG Min;MENG Fanyue;ZHAO Yan;SONG Bing(School of Energy and Environment,Southeast University,Nanjing 210096,China)

机构地区：[1]东南大学能源与环境学院,江苏南京210096

出　　处：《生态环境学报》2020年第4期834-841,共8页Ecology and Environmental Sciences

基　　金：江苏省自然科学基金项目(BK20181142)。

摘　　要：通过考察生物炭、FeAl-LDHs和FeAl-LDHs/生物炭复合材料对土壤中镉的钝化效果,筛选出最佳的钝化材料并分析其钝化机理,为土壤中镉钝化剂的筛选提供理论依据。采用水热法制备了FeAl-LDHs和FeAl-LDHs/生物炭复合材料,分别添加0.4 g FeAl-LDHs、FeAl-LDHs/生物炭复合材料及生物炭于10 g 5、10、20 mg·kg-1人工模拟镉污染土壤,采用二乙烯三胺五乙酸(DTPA)浸取法、毒性特征浸出实验(TCLP)以及改进的BCR连续提取法评价不同材料对土壤中镉的钝化效果,同时考察了FeAl-LDHs/生物炭复合材料钝化镉的稳定性。采用SEM、N2吸附、FTIR、XRD等手段分析所制备材料的形貌结构和理化特性,揭示复合材料钝化镉的作用机制。结果表明,与FeAl-LDHs和生物炭相比,FeAl-LDHs/生物炭复合材料对DTPA-Cd和镉浸出毒性有较好的钝化效果,其中添加复合材料后5 mg·kg^-1镉污染土壤DTPA-Cd含量降低90.08%,浸出毒性降至0.044 mg·L^-1,反应达到56 d时,镉污染土壤中DTPA-Cd和浸出毒性没有明显增加,5 mg·kg^-1土样浸出毒性维持在0.039mg·L^-1,FeAl-LDHs/生物炭修复效果稳定性较好。这主要归因于生物炭大的比表面积和孔结构有利于表面LDH的负载和分散,为镉的钝化提供了更多的附着位点。同时,FeAl-LDHs/生物炭复合材料表面丰富的含氧官能团和金属-氧键能够与Cd^2+发生配位反应,可以促进土壤中镉由弱酸提取态向残渣态转化,降低Cd的生物有效性和迁移性。By examining the passivation effect of biochar,FeAl-LDHs and FeAl-LDHs/biochar composites on cadmium in soil,the best passivation material was selected and its passivation mechanism was analyzed,which provided theoretical basis for the selection of cadmium passivation agents in soil.In this study,FeAl-LDHs and FeAl-LDHs/biochar composites were prepared by hydrothermal method.0.4 g of FeAl-LDHs,biochar and FeAl-LDHs/biochar composites were added at 10 g 5,10,20 mg·kg^-1 artificially simulated cadmium contaminated soils.Diethylenetriaminepentaacetic acid(DTPA),toxicity characteristic leaching procedure(TCLP)and modified european communities bureau of reference(BCR)sequential extraction procedure were used to evaluate the passivation effect of different materials on cadmium.The stability of FeAl-LDHs/biochar composites to passivating cadmium was also investigated.The morphology and physicochemical properties of the prepared materials were analyzed by scanning electron microscopy(SEM),N2 adsorption,fourier transform infrared spectroscopy(FTIR)and X-ray diffraction(XRD).Meanwhile,the mechanism of cadmium passivation was proposed.The results showed that compared with FeAl-LDHs and biochar,FeAl-LDHs/biochar had a better passivation effect on DTPA-Cd and cadmium leaching toxicity.After adding composite materials,the content of DTPA-Cd in 5 mg·kg^-1 cadmium contaminated soil decreased by 90.08%and the leaching toxicity reduced to 0.044 mg·L^-1.When the reaction time reached 56 d,there were no significant increase in DTPA-Cd and leaching toxicity in cadmium-contaminated soil,and the leaching toxicity of 5 mg·kg^-1 soil samples was maintained at 0.039 mg·L^-1.Fe Al-LDHs/biochar had better stability to the passivation of cadmium.This is mainly due to the large specific surface area and pore structure of biochar,which are beneficial to the load and dispersion of LDH on the surface,and provide more attachment sites for the passivation of cadmium.At the same time,the abundant oxygen-containing functional groups and metal-o

关 键 词：FeAl-LDHs 生物炭 镉 配位反应 

分 类 号：X705[环境科学与工程—环境工程]