Recovery of Hexavalent Chromium Ion from Methanol with Ion Exchange Resin

Recovery of hexavalent chromium ion from methanol was investigated with commercially available nine ion exchange resins including weak anion, strong anion, weak cation, and strong cation exchangers. The effects of water concentration in water-methanol mixture on the adsorption capacity of resins were investigated. The strong and weak anion exchange resins showed high adsorption capacity for chromium both in methanol and water. The strong cation exchange resins gave relatively high adsorption capacity in methanol, but the capacity drastically decreased as the water concentration in methanol increased. Dowex SBR had the best adsorption capacity both in aqueous and methanol solutions. The adsorption equilibrium was attained within about 30 min at an initial Cr concentration of 10 mg/L with Dowex SBR. The desorption of Cr from the resin was found to be easily carried out with NaCl solution. The adsorption and desorption equilibria predicted that the concentration of Cr from methanol into NaCl eluent was possible. Furthermore, five successive adsorption-desorption cycles were successfully carried out without any decline in adorption nor desorption efficiencies.