The journey traversed in the remediation of hexavalent chromium and the road ahead toward greener alternatives-A perspective

The discharge of heavy metals from industrial wastewater beyond the permissible limit causes serious pollution to the environment. In this regard, chromium that is discharged from electroplating, tannery and dye industrial effluents poses a major health hazard in view of the carcinogenic and genotoxic nature of hexavalent chromium. It is imperative to devise effective remediation strategies to detoxify chromium keeping in view the USEPA regulatory limit. This review deals with the environmental occurrence, remediation methods and future perspectives in the sequestration of hexavalent chromium [Cr(VI)] from wastewater. Remediation methods such as solvent extraction, adsorption using polymeric resins, clays, biopolymers, biomass, activated carbon and graphene oxide are discussed with respect to their removal efficiency, regenerability, adsorption capacities and other characteristics. Considerable emphasis is laid on the utility of chelating adsorbents and ionic liquid impregnated adsorbents for the remediation of chromium from tannery and electroplating wastewater. The review examines published data in last few years concerning the removal of toxic Cr(VI) with a critical evaluation on the merits and demerits of each of the processes and the road ahead towards formulating more effective strategies. (C) 2016 Elsevier B.V. All rights reserved.