A comparative performance of two resins based on polysterene for removal of chromium(III) from tannery solution

Extraction of chromium(III) from a model tanning waste solution was compared by ion exchange using two sulfonated polysterene based resins viz. Indion 790 and Amberlite IR 120. These resins showed similar extraction behaviour towards chromium(III) from a model solution containing 500 ppm chromium(III). In the acidic region pH had no effect on the extraction of chromium(III). Beyond pH 3.5 extraction of chromium(III) with Indion 790 drastically decreased from 92 % to 76 % whereas, Amberlite IR – 120 was effective even up to 4.5 pH. Sorption of chromium(III) on Indion 790 and Amberlite IR 120 followed Freundlich and Langmuir isotherms. However, higher Freundlich constant values indicate strong chemical interaction of the metal ion with the resins. Desorption of chromium(III) from the loaded resins increased with the increase in concentration of eluant (5-20% H2SO4). With 20% sulfuric acid solution 89% chromium(III) was eluted from loaded Indion 790 in two stages, and from loaded Amberlite IR 120, 94% chromium(III) was eluted in three stages.