Chitosan Biocomposites with Variable Cross-Linking and Copper-Doping for Enhanced Phosphate Removal

Area of Science:

• Materials Science
• Environmental Science
• Chemistry

Background:

• Chitosan (CH) is a sustainable polysaccharide with potential for water remediation.
• Copper (Cu²⁺) doping can enhance the adsorption properties of chitosan materials.
• Phosphate removal is crucial for mitigating eutrophication in aquatic environments.

Purpose of the Study:

• To fabricate chitosan biocomposite beads with controlled copper ion doping using different methods.
• To investigate the impact of cross-linking and copper doping on bead properties and phosphate adsorption.
• To evaluate the efficiency and reusability of copper-doped chitosan beads for phosphate removal.

Main Methods:

• Fabrication of chitosan beads with variable copper doping via three distinct methods, with and without glutaraldehyde cross-linker (CL).
• Characterization using spectroscopy (FTIR, ¹³C NMR, XPS), SEM, TGA, solvent swelling, and phosphate adsorption isotherms.
• Adsorption and regeneration studies at pH 8.5 and 295 K to determine adsorption capacity and reusability.

Main Results:

• Variable cross-linking and copper doping were achieved, influencing bead structure and properties.
• Non-cross-linked copper-imbibed beads (CH-b-Cu) exhibited the highest phosphate affinity (Q = 133 ± 45 mg/g) due to higher copper loading and swelling.
• Copper-imbibed chitosan beads demonstrated over 80% regenerability, indicating cost-effectiveness and sustainability.

Conclusions:

• A facile synthetic approach for controlled copper doping onto chitosan beads was established.
• Chitosan-based biocomposites offer tailored phosphate oxyanion uptake for water remediation.
• This study presents a sustainable polysaccharide adsorbent for mitigating eutrophication.