Use of ion exchanger for removal and recovery of chromium (VI) from water

Hexavalent chromium [Cr (VI)], a significant heavy metal pollutant in industrial wastewater, poses serious environmental and health risks due to its toxicity and genetic alteration potential. In this study, the removal of Cr (VI) ions was investigated using the strong basic anion exchange resin Amberlite IRA 402. Batch experiments were conducted to evaluate the effects of contact time, pH, and adsorbent concentration on Cr (VI) removal. Under optimal conditions, the equilibrium time for an initial concentration of 100 mg/L Cr (VI) and an adsorbent concentration of 0.15 g/100 mL was determined to be 12 minutes, with a Lagergren rate constant of 0.250 min⁻¹. It was observed that pH significantly influenced Cr (VI) removal, with the maximum adsorption capacity recorded as 132.63 mg/g at pH 3.50. However, the removal efficiency decreased as the pH increased to 7.50. Regeneration experiments using NaCl solution demonstrated that increasing the concentration and volume of NaCl enhanced the chromium removal efficiency. Experiments conducted with synthetic groundwater revealed that the presence of competing ions reduced the Cr (VI) removal capacity to 33.22 mg/g. Furthermore, comparative experiments with granular activated carbon showed that the Cr (VI) removal capacity of Amberlite IRA 402 ion exchange resin was superior to that of granular activated carbon. Keywords: Hexavalent Chromium, Adsorption, Amberlite IRA 402, Anion Exchange Resin, Industrial Wastewater, Granular Activated Carbon