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Remediation of Cr(VI)-Contaminated Soils by Washing with Low-Molecular-Weight Organic Acids Based on the Distribution of Heavy Metal Species
Environmental Engineering Science ( IF 1.8 ) Pub Date : 2022-01-20 , DOI: 10.1089/ees.2021.0018
Shaolin Tan 1 , Yi Xin 2 , Kun Liu 3 , Enzhi Zhang 1 , Shijie Li 1 , Manqing Zhao 1 , Huanfang Gao 1
Affiliation  

In this article, low-molecular-weight organic acids were applied to remediate the hexavalent chromium [Cr(VI)]-contaminated soil. The influence of different parameters (washing concentration, solid–liquid ratio, time, and pH value) on the repair effect was explored, and the form distribution and desorption kinetic experiments of the soil were performed. The results show that the pH of eluents can significantly affect the form distribution of chromium, with the exchangeable form increasing considerably at a lower pH. The kinetics of Cr(VI) desorption can be described by the pseudo-second-order kinetics equation. The best washing scheme was determined to be the citric acid as the eluent at a concentration of 0.3 mol/L, a solid to liquid ratio of 1:10, pH 4, and a washing time of 6 h. The removal rate can be as high as 73.52%. After washing, the leaching concentration of Cr(VI) in the soil was reduced from 23.76 to 1.05 mg/L, well below the regulatory constraint of 5 mg/L. Additionally, the characterizations of X-ray diffractometer and scanning electron microscope showed little effect of adopting citric acid as a washing agent on soil structure and surface morphology. This study can provide a theoretical basis for the remediation of Cr(VI)-contaminated soil at industrial sites.

中文翻译:

基于重金属分布的低分子有机酸洗涤修复Cr(VI)污染土壤

本文采用低分子有机酸修复六价铬[Cr(VI)]污染土壤。探讨了不同参数(洗涤浓度、固液比、时间、pH值)对修复效果的影响,并进行了土壤形态分布和解吸动力学实验。结果表明,洗脱液的pH对铬的形态分布有显着影响,在较低的pH下可交换形态显着增加。Cr(VI)解吸的动力学可以用准二级动力学方程来描述。确定最佳洗涤方案为柠檬酸作为洗脱液,浓度为 0.3 mol/L,固液比为 1:10,pH 为 4,洗涤时间为 6 h。去除率可高达73.52%。洗完后,土壤中 Cr(VI) 的淋溶浓度从 23.76 降至 1.05 mg/L,远低于 5 mg/L 的监管限制。此外,X射线衍射仪和扫描电镜的表征表明,采用柠檬酸作为清洗剂对土壤结构和表面形态影响不大。该研究可为工业场地Cr(VI)污染土壤的修复提供理论依据。
更新日期:2022-01-20
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