Cellulose-based thermosensitive supramolecular hydrogel for phenol removal from polluted water

Pollution of phenolic effluent from spice and plastics factories has become increasingly serious. Thus, developing a green and highly efficient adsorbent to remove phenolic compounds from wastewater is of urgent need. In this study, cellulose graft copolymer was synthesized through grafting 4-vinylpyridine monomer and polyethylene glycol methacrylate to a molecular skeleton of cellulose by free radical polymerization. The supramolecular hydrogel was successfully synthesized by physical cross-linking of cellulose graft copolymer and α-cyclodextrin. These supramolecular hydrogels were thoroughly characterized and the adsorption performance (adsorption isotherms and adsorption kinetics) of phenol on the supramolecular hydrogel were investigated in batch operation. The supramolecular hydrogel not only exhibited excellent adsorption of phenol, but also demonstrated increased mechanical strength due to the introduction of a modified cellulose base material. The adsorption kinetics of phenol on the supramolecular hydrogel followed a quasi-second-order reaction, with a correlation coefficient of 0.9909. The adsorption isotherm conformed to the Langmuir adsorption isotherm, and the maximum adsorption capacity of phenol can reach 80.71 mg g^-1, which was 2-3 times higher than traditional carbon-based materials. The results demonstrate the great promise of the waste-derived supramolecular hydrogel to be used as an efficient adsorbent in wastewater treatment.