Equilibrium and kinetic study of chromium sorption on resins with quaternary ammonium and N-methyl-d-glucamine groups

• Faster chromium adsorption using copolymer resin than commercial IEX resins.
• Sulfate and chloride do not interfere significantly on chromium sorption.
• Copolymer does not loss sorption capacity after three adsorption/desorption cycles.

The equilibrium and kinetics of chromium (VI) adsorption on a new synthesized resin containing both N-methyl-d-glucamine and quaternary ammonium functional groups P(VbNMDG-co-ClVBTA) have been presented. The results obtained for the new copolymer were compared with those for two commercial resins, namely Amberlite IRA-743 and IRA-400, containing only N-methyl-d-glucamine and quaternary ammonium functional groups, respectively. The effect of adsorbent dose, pH, temperature, and interfering ions on chromium removal was studied. The maximum chromium uptake for the copolymer was 677.9 mg gresin−1 at pH 4-5, while those for IRA-400 and IRA-743 were 893.4 and 316.6 mg gresin−1, respectively. Chloride and sulfate anions did not exhibit an effect on chromium sorption for the copolymer and IRA-400; however, sorption on the IRA-743 resin was affected. The adsorption kinetics and isotherms as well as thermodynamic parameters were evaluated. Increasing temperature decreased the chromium adsorption for both commercial and synthesized resins, revealing the exothermic nature of the process. The Freundlich and Langmuir isotherm models were used to describe the adsorption of Cr(VI) onto resins. Kinetic studies revealed that Cr(VI) reached over 99% removal at 10, 30, and 240 min for the copolymer, IRA-400, and IRA-743, respectively. Chromium adsorption/desorption cycles were performed to estimate the adsorbent lifetime, where the copolymer resin exhibited a better performance than IRA-400, and IRA-743, achieving a high efficiency after 3 cycles.

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