Efficient removal of hexavalent chromium ions from simulated wastewater by functionalized anion exchange resin: Process optimization, isotherm and kinetic studies

In the present study, hazardous heavy metal ion hexavalent chromium (Cr(VI)) was removed from aqueous solution by using Indion GS-300 (IGS-300), strong base anion exchange resin. The process parameters for the removal of Cr(VI) were optimized using response surface methodology (RSM) approach. Procured resin was analyzed by various techniques like FTIR, and FESEM associated with elemental analysis which provided functional groups and surface structure of the adsorbents. Various batch adsorption experiments were conducted by varying parameters such as Cr(VI) concentrations from 5 mg/L to 45 mg/L, 2 to 10 pH, IGS-300 resin dosage between 0.38 and 1.88 g/L, and temperature of 20–40 °C with 90 min fixed contact time. Fixed time was determined from preliminary study of the present work. The maximum adsorption capacity of IGS-300 resin was found 294.11 mg/g and 98.20% of removal achieved with optimum conditions of 4 pH, 1.50 g/L adsorbent dosage, 15 mg/L Cr(VI) concentration and 35 °C temperature. The experimental data was found with best fitted Freundlich Isotherm and pseudo second order kinetic model. Regeneration study was also done on the adsorbed resins using different solution includes water, 0.1 M HCl, and 0.1 M NaOH. Up to 3 cycles of 0.1 M NaOH treatment, resin showed >50% Cr(VI) removal in aqueous solution whereas water and HCl were found less effective on third cycle. Therefore, this study found that IGS-300 resin is more efficient adsorbent for the removal of Cr(VI) from aqueous solutions and possessing highly significant regeneration capacity.