Chromium(III) Removal from Wastewaters by a Weakly Acidic Resin Containing Carboxylic Groups

Abstract

As a conservative technology, ion exchange allows the removal and recycling of metals from liquid effluents. A process was applied for the removal of chromium(III) from wastewaters by ion exchange. This process was based on a weakly acidic cation-exchange resin (Amberlite IRC 86) capable of removing chromium(III) from the effluent, followed by selective separation and recovery during a regeneration procedure.Because of the difficult regeneration behaviour of the metal form of the carboxylate resin, special emphasis was given to the regeneration step of the resin where most of the practical problems were found. Five different regeneration procedures were adopted: elution with 1 M NaOH; elution with 1 M H2SO4; elution with 1 M NaOH followed by 1 M H2SO4 or vice versa; elution with NaOH followed by 1 M H2SO4/Na2SO4 solution; and elution with alkaline H2O2/NaOH solutions followed by 1 M H2SO4. A non-conventional regenerant solution such as hydrogen peroxide in an alkaline medium seemed very promising. The ani...