Remediation of hexavalent chromium from aqueous solution using clay mineral Fe(II)–montmorillonite: Encompassing anion exclusion impact

Abstract

We have explored the highly efficient and environmentally benign clay mineral, Fe(II)–montmorillonite, for the reduction of Cr(VI) in aqueous solution. Fe(II)–Mt was treated with K2Cr2O7 solution at different pH, temperature and solid-to-liquid ratio. The [Cr2O7]2− was estimated by UV–vis spectra with a correction for anion exclusion impact. In general, the Cr(VI) reduction was rapid at acidic pH and increased with temperature up to 50°C. A complete reduction occurred in about 5min at pH 3–5. The time taken for complete reduction at 0°C, RT (30°C) and 40°C are 12min, 8min and 5min, respectively. The reduction followed by immobilization of Cr(III) on the spent clay mineral was well characterized by EDX and chemical extraction analysis. This remediation process could be easily scaled-up for real system applications.