Removal of chromium(III) by cation exchange resin, Indion 790 for tannery waste treatment

Extraction of chromium(III) from a model solution and from a tannery waste solution was studied by ion exchange using Indion 790 resin which is a macro-porous strongly acidic cation exchange resin of sulfonated polystyrene group. The resin was found to be selective for the sorption of chromium(III) in the pH range 0.5–3.5 from a model solution containing 500 ppm Cr(III). Beyond pH 3.5 extraction of chromium(III) drastically decreased from 92% to 76%. Sorption of chromium(III) on Indion 790 followed the Freundlich isotherm with a high Freundlich constant value (Kf = 8.57) confirming strong chemical interaction of the metal ion with the resin. Desorption of chromium(III) from the loaded resin increased with the increase in concentration of eluant (5–20% H2SO4). With 20% sulfuric acid solution 89% Cr(III) was eluted in two stages. The bench scale results were also validated in continuous mode in a fixed bed column and for the recovery of chromium(III) from a tannery solution.