Integration of ion exchange and electrodeionization as a new approach for the continuous treatment of hexavalent chromium wastewater

Mining and electroplating wastewaters contain many harmful ions, which are discharged into waterways and water bodies and cause significant environmental damage. Hexavalent chromium (Cr(VI)) is an ion that is commonly present in these effluents, which has been proven as toxic to humans. In the present work, continuous ion exchange and electrodeionization are proposed as a new hybrid technology for the effective treatment of Cr(VI) wastewater as well as the recovery of chromium ions. We have systemically studied a strong basic macroreticular anion exchange resin (Amberlite® IRA900) for the removal of Cr(VI). The ion exchange isotherm and kinetics of the resin were determined, showing that the IRA900 anionic ion exchange resin has a high capacity for ion exchange with hexavalent chromium (116 mg Cr(VI) per gram of resin). When the anionic resin was combined with a strong acidic macroreticular cation exchange resin (Amberlite® 200C) and employed in continuous electrodeionization, over 98.5% of Cr(VI) was continuously removed from the dilute compartment with an energy consumption of less than 0.07 kW h/m3, while Cr(VI) was recovered in the concentrate compartment.

► <0.01 ppm of Cr(VI) was reached by continuous ion exchange from 100 ppm. ► Over 98.5% of Cr(VI) was continuously removed by the continuous electrodeionization process. ► Integration of ion exchange and electrodeionization. ► Energy consumption was less than 0.07 kW h/m3.