Peng Cheng, Gong Kailin, Li Qiannan, Liang Weiyu, Song Huihui, Liu Fang, Yang Jie, Zhang Wei
State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Chemosphere. 2023 Feb;313:137453. doi: 10.1016/j.chemosphere.2022.137453. Epub 2022 Dec 1.
Magnesium-aluminum modified biochar (MABs) has an outstanding effect on the simultaneous immobilization of arsenic (As), lead (Pb), and cadmium (Cd) in soil, but the stability of remediation effect of MAB under various natural conditions is still unknown. In this study, we investigated the effects of organic acids, dry-wet cycles (DW), freeze-thaw cycles (FT), and rainfall (pH 4, 7, and 8) on the immobilization of As, Pb, and Cd by MAB. The results showed that oxalic acid decreased the immobilization efficiencies of As, Pb, and Cd by 15.5%-38.5%; meanwhile, humic acid reduced the immobilization efficiency of Pb by 89.7%, but elevated that of Cd by 19.5%. The immobilization mechanisms of MAB-5 on three metals were mainly involved in ion exchange and surface-complexation. Compared with the 7th round, the immobilization efficiencies of As, Pb, and Cd by MAB in the 28th round was decreased by 17%-28% in DW, but was increased by 11%-18% in FT. In addition, MAB was transformed into hydrotalcite after FT and DW. After experiencing simulated rainfall, MAB caused more As, Pb, and Cd to be retained in the upper soil layer, and the immobilization effect of MBA was more significant under the stimulated rainfall with higher pH. The study provides a more theoretical basis for the application of MAB in the actual site remediation.
镁铝改性生物炭（MABs）对土壤中砷（As）、铅（Pb）和镉（Cd）的同步固定具有显著效果，但MAB在各种自然条件下修复效果的稳定性仍不清楚。在本研究中，我们研究了有机酸、干湿循环（DW）、冻融循环（FT）和降雨（pH值为4、7和8）对MAB固定As、Pb和Cd的影响。结果表明，草酸使As、Pb和Cd的固定效率降低了15.5%-38.5%；同时，腐殖酸使Pb的固定效率降低了89.7%，但使Cd的固定效率提高了19.5%。MAB-5对三种金属的固定机制主要涉及离子交换和表面络合。与第7轮相比，MAB在第28轮对As、Pb和Cd的固定效率在DW中降低了17%-28%，但在FT中提高了11%-18%。此外，FT和DW后MAB转变为水滑石。经历模拟降雨后，MAB使更多的As、Pb和Cd保留在上层土壤中，且在较高pH值的模拟降雨下MAB的固定效果更显著。该研究为MAB在实际场地修复中的应用提供了更多理论依据。
