Hybrid Properties of Alginate‐PEI Adsorbent for Chromium (VI) Removal from Aqueous Solutions

Abstract

An adsorbent consisting of polyethyleneimine (PEI) immobilized in calcium alginate gel beads was synthesized and evaluated for Cr⁶⁺ removal. An evaluation of the synthesis process showed the importance of the PEI molecular weight on the immobilization efficiency. Polyethyleneimine of 70,000 Da molecular weight displayed the highest immobilization percentage at 52%. Batch kinetics and equilibrium tests showed that alginate‐PEI (APEI) resin displayed considerable affinity for negatively charged Cr⁶⁺ complexes at low pH conditions ranging from pH 1.5‐pH 3. The results also indicated the reduction of Cr⁶⁺ to less toxic Cr³⁺ species by the APEI adsorbent. The column adsorption experiments showed the ability of APEI resin to treat a 10 mg/L Cr⁶⁺ solution with pH influent adjustment from pH 1.5 to pH 3 to concentrations that satisfy effluent standards for Cr⁶⁺ (<0.1 mg/L) and total Cr (<0.5 mg/L). Finally, comparisons with a highly aminated commercial resin Chitopearl CS‐03 highlighted the unique ability of the hybrid APEI beads with its amine and carboxylic groups for the adsorption of Cr⁶⁺ as well as the retention of generated Cr³⁺ ions.

Keywords:

• Adsorption
• alginate
• polyethyleneimine
• immobilization
• chromium (VI)
• wastewater treatment

Acknowledgement

This research was supported by The New Energy and Industrial Technology Development Organization of Japan.