An environmentally friendly strategy for reducing the environmental risks of heavy metals adsorbed by kaolinite

• Published in: Journal of environmental management 2024-03, Vol.355, p.120506-120506, Article 120506
• Main Authors: Shang, Zhongbo, Wang, Tianming, Ye, Quanyun, Wu, Pingxiao, Wu, Jiayan, Sun, Leiye, Zhu, Nengwu
• Format: Article
• Language: English
• Subjects: Aging; Cadmium; Calcium silicate and magnesium silicate; Environmental Pollution; Kaolin; Kaolinite; Lead; Metals, Heavy - analysis; Oxalic acid; Pb2+ and Cd2; Soil; Soil Pollutants - analysis
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2024.120506

Plenty of heavy metals (HMs) that are adsorbed on clay minerals (such as kaolinite), in addition to low molecular-weight organic acids (such as oxalic acid (OA)) with high activities, are widespread in the natural environment. In the present study, the effects of OA on the environmental behaviors of Pb2+/Cd2+ adsorbed by kaolinite have been investigated. The effectiveness and mechanisms of calcium silicate (CS) and magnesium silicate (MS) in reducing the environmental risks of the HMs have also been studied. The results showed that the releases of Pb2+/Cd2+ increased with an increasing concentration of OA. When different dosages of CS/MS were added to the aging system, a redistribution of HMs took place and the free form of Pb2+/Cd2+ decreased to very low levels. Also, the unextractable Pb2+/Cd2+ increased to high levels. Furthermore, a series of characterizations showed that the released HMs were re-captured by the CS/MS. In addition, the CS immobilized the OA in the solution during the aging process, which also facilitated an immobilization of the carbon element in the environment. In general, the present study has contributed to a further understanding of the transport behaviors of the HMs in natural environments, and of the interactions between CS (or MS), the environmental media, and the heavy metal contaminants. In addition, this study has also provided an eco-friendly strategy for an effective remediation of heavy metal pollution. [Display omitted] •Oxalic acid promoted the release of heavy metals fixed by kaolinite.•The silicate materials can effectively inhibit the migration of heavy metals.•The silicate materials can obviously change the form distribution of heavy metals.•The release of all metal cations and Si element during the aging process was studied.