Layered double hydroxides as versatile materials for detoxification of hexavalent chromium: Mechanism, kinetics, and environmental factors

• Published in: Journal of environmental chemical engineering 2024-12, Vol.12 (6), p.114742, Article 114742
• Main Authors: Nemati, Seyed Saman, Dehghan, Gholamreza, Khataee, Alireza, Alidokht, Leila, Kudaibergenov, Nurbolat
• Format: Article
• Language: English
• Subjects: Hexavalent chromium; Layered double hydroxides; LDH modifications; Pollutant removal; Trivalent chromium
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.114742

Hexavalent Cr (CrVI) compounds are a common environmental pollutant that causes carcinogenesis and interferes with the normal process of the cells. Layered double hydroxides (LDHs) as a class of ionic solids with hydroxylated metals in two layers and an intermediate layer containing water molecules and anions, e.g., CO32−, SO42−, Cl−, can be used for wastewater treatment, controlled drug delivery, pharmaceuticals, cosmetics, and electrochemical sensors. The use of LDHs to remove CrVI from aqueous environments has been considered because they have advantages such as biocompatibility and high efficiency. CrVI is converted to the less dangerous trivalent Cr (CrIII) by some of the LDHs, e.g., MgFe LDH, MgAl LDH, and NiFe LDH. In this review, after a summary of the LDHs principle, the main mechanisms of CrVI removal, including adsorption, interlayer ion exchange, and redox process, and the kinetics of CrVI removal have been described. The influential factors in CrVI removal efficiency by LDHs, including modification of LDHs, pH, and the effect of LDH interlayer anions, were reviewed in depth. The appropriate selection of interlayer anion, using intercalated LDHs, LDHs composite developing, as well as divalent and trivalent metals of LDHs, is effective in its performance; Also, modifying LDHs and preparing LDH-composites can improve the efficiency of removing CrVI. [Display omitted] •LDH development in CrVI removal, as a hazardous pollutant, from solution was reviewed.•The mechanism of CrVI removal by LDHs is mainly based on sorption and reduction.•LDHs, with their high efficiency, remove an extensive percentage of CrVI, providing a reassuring level of effectiveness.•Intercalated LDHs are recommended to increase adsorption efficiency.•LDH-based composites using synergistic and multifunctional abilities in removing CrVI are recommended.