Removal of carcinogenic chromium(VI) from effluent of electroplating industry using adsorptive separation

The wastewater from an electroplating industry contains chromium VI which is highly carcinogenic at a typical level of 21.5 to 47 mg L⁻¹ which should be reduced to acceptable value of 0.05 mg L⁻¹ for the water to be suitable for drinking purpose. In this study, Tulsion A23 resin was applied as an adsorbent for successful removal of Cr(VI), also dealing with understanding the effect of various parameters on extent of removal of the contaminant. It was elucidated that contact time of 120 min is required for the equilibrium and the optimum pH value was 5 and the optimum resin loading was 4 g L⁻¹ at which 97% Cr(VI) removal was observed. Different adsorption isotherm models were applied and it was elucidated that Langmuir model was the best fit with R² as 0.99. In the case of kinetic study, pseudo-second order model was best fitted with higher R² value. The regeneration of the resin was performed using 3 M NaOH and it was shown that after the three cycles of regeneration, the resin showed 82% Cr(VI) removal. Overall, successful application of Tulsion A23 resin was demonstrated for the removal of Cr(VI) from real effluent for the first time.