Facile fabrication of carboxymethyl cellulose film via crosslinking approach for decolorization of cationic dyes.

Carboxymethyl cellulose (CMC), an economical and eco-friendly anionic polymer, exhibits strong adsorption capacity toward cationic metals and dyes. Nevertheless, due to weak intermolecular interactions within the biopolymer chains, the practical application of these materials is frequently constrained by their poor mechanical strength and high aqueous solubility. Here, an efficient film adsorbent, primarily composed of CMC, was readily fabricated via a crosslinking strategy employing ethylene glycol diglycidyl ether (EGDE) as a non-toxic crosslinking agent, effectively addressing these challenges simultaneously. The crosslinked film possessed excellent swelling ability and integrity in neutral, in acidic and in alkaline media. Furthermore, when the molar feed ratio of EGDE to CMC was 2.2, the tensile strength was 80.40 MPa, and elongation at break was 7.01%. Building on this, methylene blue (MB) was selected as the target adsorbate to evaluate the decolorization performance of the crosslinked film. The adsorption data manifested that the adsorption process agreed with the Langmuir model and pseudo-second-order kinetic model, and theoretical maximum adsorption capacity was 1724.1 mg/g. Additionally, the crosslinked film also exhibited high selectivity for cationic dyes and could be efficiently regenerated through hydrochloric acid/ethanol treatment, achieving nearly complete desorption. This work fully leverages the potential of hydroxyl- and carboxy-rich CMC, advancing the development and practical application of sustainable polymeric materials.