Synthesis of Cellulose Nanofiber-Enhanced Hydrogels for Efficient Cu²⁺ Ion Adsorption

The contamination of water sources with heavy metal ions, especially Cu²⁺, has been on the rise, and hence, there is a need to develop efficient and sustainable adsorbent materials. This study aims at synthesizing cellulose nanofiber (CNF)-enhanced hydrogels for Cu²⁺ ion adsorption to improve adsorption capacity, mechanical stability, and reusability. Hydrogels were synthesized through free radical polymerization, incorporating CNFs to enhance structural integrity and surface area. The characterization by FTIR, SEM, and swelling studies proved that hydrogels were successfully synthesized with improved porosity. The batch adsorption experiments revealed high Cu²⁺ removal efficiency for CNF-enhanced hydrogels and attained rapid equilibrium of adsorption under optimized pH and contact time conditions. Adsorption was based on the Langmuir isotherm and pseudo-second-order kinetics, with evidence of monolayer adsorption and a strong binding affinity. Regeneration studies confirmed multiple cycles of adsorption, indicating the sustainability potential of the hydrogel. These findings highlight the potential application of CNF-enhanced hydrogels in wastewater treatment, providing an eco-friendly and cost-effective solution for heavy metal remediation.