Efficient fabrication of cellulose-based hydrogels for effective heavy metal ion adsorption from oral medical wastewater.

Heavy metal contamination in oral medical wastewater poses increasing environmental concerns, while the practical application of cellulose-based adsorbents is often limited by insufficient structural stability and complicated fabrication procedures. In this work, a mechanically robust cellulose-based composite hydrogel (MCC@MF) was fabricated through a facile dip-gelation and solvent-exchange strategy using commercially available melamine foam (MF) as a supporting scaffold. The interconnected porous framework facilitated solution infiltration and ion transport, while regenerated cellulose provided abundant adsorption sites for heavy metal ions. The MCC@MF hydrogel exhibited effective adsorption performance for Co2+, Cd2+, Cu2+, and Ni2+ ions, with a maximum adsorption capacity of 136.2 mg g-1 for Co2+. Adsorption kinetics and intraparticle diffusion analysis suggested that the adsorption process involved combined diffusion and chemisorption contributions. In addition, the hydrogel maintained stable framework integrity and adsorption performance after repeated adsorption-desorption cycles, and retained approximately 79% of its initial adsorption capacity after five adsorption-desorption cycles. Real oral medical wastewater experiments further demonstrated the applicability of the MCC@MF hydrogel in complex multi-ion systems. This work provides a simple and robust strategy for preparing cellulose-based composite hydrogels for heavy-metal-containing wastewater treatment.