Chemical crosslinking reinforced flexible cellulose nanofiber-supported cryogel

A robust and flexible cellulose nanofiber (CNF)-supported cryogel was prepared by chemical crosslinking method using gamma-glycidoxypropyltrimethoxysilane (GPTMS) and branched polyethylenimine (PEI). FT-IR, elemental analysis, EDS and solid state C-13 NMR analysis revealed that the PEI had been successfully modified on cellulose via reacting with GPTMS. The obtained flexible cryogel displayed a three-dimensional structure composed of thin sheet. The maximal shape recovery of the CNF-supported cryogel from a 50% compression strain was up to 93% of its original thickness. The cryogel contained abundant amino groups and proved to be efficient in removing Cu2+ from solution with a maximum Cu2+ uptake of 138 mg/g. The adsorption kinetics curve fitted the pseudo-second-order model and the equilibrium absorption capacity fitted the Langmuir model. Moreover, adsorption capacity of the cryogel was up to 75% after four adsorption-desorption cycles (15 days).