Removal of chromium(VI) from the leachate of electronic scrap using non-ionic Amberlite XAD-7HP resin

Background In order to recover the valuable metals from the leach liquor of electronic scrap, it is necessary to remove/recover chromium(VI) due to its high toxicity. The non-ionic ion exchange resin, Amberlite XAD-7HP has been employed in the present research to remove Cr(VI) as it possesses large surface area and porosity to adsorb chromium selectively from complex leach solutions in the presence of other ionic species. Results Amberlite XAD-7HP resin effectively adsorbed chromium in the range of acidity from 0.3 to 2.0 mol L1. The sorption capacity was found to be 16.9 mg Cr g1 resin in 30 min under the experimental conditions used. Studies carried out with actual leach solution containing Cu, Zn, Ni, Sn, Pb, Au, Cd and Cr showed the selective adsorption of both Cr and Au as they are present in the solution in an anionic form. Cr was then selectively eluted with water/dilute sodium hydroxide from the loaded resin. Subsequently, Au could be eluted with mixed solution of hydrochloric acid and acetone to regenerate the resin for recycle. Conclusion Amberlite XAD-7HP resin is suitable and effective for the removal of Cr(VI) from complex leachate of electronic scrap. The other associated metals in the leach solution could be recovered in subsequent steps generating a final solution which could be discharged to the environment.