Boosted Cr(VI) sorption coupled reduction from aqueous solution using quaternized algal/alginate@PEI beads

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Hexavalent chromium (Cr(VI)) poses significant environmental and health risks.
• Effective and stable sorbent materials are crucial for Cr(VI) remediation.
• Algal/alginate-PEI (APEI) beads offer a potential platform for heavy metal removal.

Purpose of the Study:

• To develop and characterize quaternized APEI (Q-APEI) beads for enhanced Cr(VI) removal.
• To investigate the combined sorption and reduction mechanisms of Cr(VI) by Q-APEI.
• To evaluate the performance of Q-APEI in batch and fixed-bed systems.

Main Methods:

• Quaternization of APEI beads to create Q-APEI.
• Batch sorption experiments to determine optimal pH and sorption capacity.
• Kinetic and isotherm studies using pseudo-second-order and Sips models.
• Fixed-bed column experiments to assess performance in dynamic systems.
• Characterization using FTIR, XPS, SEM, and EDS to elucidate the removal mechanism.

Main Results:

• Q-APEI exhibited optimal Cr(VI) sorption and reduction near pH 2.
• Maximum sorption capacity reached 334 mg Cr(VI)/g, with ~25% reduction to Cr(III).
• Sips and pseudo-second-order models accurately described sorption isotherms and kinetics, respectively.
• The Yan model effectively predicted breakthrough curves in fixed-bed systems.
• Q-APEI demonstrated remarkable stability over three sorption-desorption cycles.

Conclusions:

• Reduction-assisted sorption significantly enhances overall Cr(VI) removal by Q-APEI.
• Q-APEI is a stable and highly effective sorbent for Cr(VI) remediation.
• The developed material shows promise for practical applications in wastewater treatment.