Structural transformation and performances of green rust for water decontamination: A review

In recent years, green rust (GR) has received considerable attention for its role in the structural transformation of iron minerals and environmental remediation. However, understanding GR's redox transformations under hydrological fluctuations remains unclear. This paper reviews the sources, structures, and properties of GR in natural environments. It summarizes the redox transformations of GR under various environmental conditions and comprehensively evaluates the remediation of inorganic and organic pollutants. Changes in the interlayer components of GR regulate its physicochemical properties (such as interlayer spacing, redox potential, and thermal stability). Besides the well-known oxidation-driven transformations of GR into secondary minerals (e.g., ferrihydrite, lepidocrocite, goethite, and magnetite), this review also outlines the complex transformations driven by biotic and abiotic factors under anoxic conditions. It summarizes the diverse remediation performances of GR on water pollutants through adsorption, reduction reactions, and oxidation reactions. Furthermore, the paper analyzes the relationship between the structural transformation of GR and its reactivity. It identifies gaps and challenges in understanding GR's structural transformations and pollutant remediation, providing valuable research directions for future studies.