Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
J Environ Manage. 2021 Oct 15;296:113174. doi: 10.1016/j.jenvman.2021.113174. Epub 2021 Jul 5.
Chemical washing has been carried out to remediate soil contaminated with heavy metals. In this study, the appropriate washing conditions for N,N-bis(carboxymethyl)-L-glutamic acid (GLDA) combined with ascorbic acid were determined to remove As, Cd, and Pb in the soil from the smelting site. The mechanism of heavy metal removal by the washing agent was also clarified. The results showed that heavy metals in the soil from the smelting site can be effectively removed. The removal percentages of As, Cd, and Pb in the soil from the smelting site were found to be 34.49%, 63.26%, and 62.93%, respectively, under optimal conditions (GLDA and ascorbic acid concentration ratio of 5:20, pH of 3, washing for 60 min, and the liquid-to-solid ratio of 10). GLDA combined with ascorbic acid efficiently removes As, Cd, and Pb from the soil through synergistic proton obstruction, chelation, and reduction. GLDA can chelate with iron and aluminum oxides while directly chelate with Cd and Pb. Ascorbic acid can reduce both Fe(III) to Fe(II) and As(III) to As. The dissolution of As was promoted by indirectly preempting the binding sites of iron and aluminum in the soil while those of Cd and Pb were improved by directly interrupting the binding sites. This study suggested that GLDA combined with ascorbic acid is an effective cleanup technology to remove As, Cd, and Pb simultaneously from contaminated smelting site soils.
化学淋洗已被用于修复受重金属污染的土壤。在这项研究中，确定了 N,N-双（羧甲基）-L-谷氨酸（GLDA）与抗坏血酸联合使用的合适洗涤条件，以去除来自冶炼厂的土壤中的砷、镉和铅。还阐明了洗涤剂去除重金属的机制。结果表明，来自冶炼厂的土壤中的重金属可以被有效去除。在最佳条件下（GLDA 和抗坏血酸浓度比为 5:20、pH 值为 3、洗涤 60 分钟、液固比为 10），来自冶炼厂的土壤中砷、镉和铅的去除率分别为 34.49%、63.26%和 62.93%。GLDA 与抗坏血酸通过协同质子阻塞、螯合和还原作用从土壤中有效去除砷、镉和铅。GLDA 可以与铁和铝氧化物螯合，同时直接与 Cd 和 Pb 螯合。抗坏血酸可以将 Fe(III)还原为 Fe(II)，将 As(III)还原为 As。通过间接抢占土壤中铁和铝的结合位点，促进了砷的溶解，而通过直接中断 Cd 和 Pb 的结合位点，提高了 Cd 和 Pb 的溶解。本研究表明，GLDA 与抗坏血酸联合使用是一种从受污染的冶炼厂土壤中同时去除砷、镉和铅的有效修复技术。
