Hydrogels from dextran/carboxymethyl cellulose exhibiting high post-drying swelling ratios and recovery

Abstract

Hydrogels were prepared from enzymatically synthesized (1 → 6)-α-D-glucan (dextran) and carboxymethyl cellulose (CMC) by crosslinking with ethylene glycol diglycidyl ether. The resulting dextran/CMC hydrogel was transparent, highly swellable, and self-standing. Analyses revealed that the swelling ratio of the hydrogels increased as the CMC content increased. Further, the CMC hydrogel was hard but brittle, with a relatively high elastic modulus (15.8 kPa) and low fracture strain (10.5%). With increasing dextran content, the dextran/CMC hydrogels became softer and more flexible, the elastic modulus decreased, and the fracture strain increased. The oven-dried samples of the dextran/CMC hydrogel exhibited the ability to restore their shape and size when immersed in deionized water. The adsorption of heavy metal Cu²⁺ ions and methylene blue dye on the dextran/CMC hydrogel was well described by pseudo-second-order kinetics and Freundlich isotherm models. The reusability test showed that the dextran/CMC hydrogel is a potential adsorbent that can be reused multiple times.