Preparation and Release Properties of a pH-Tunable Carboxymethyl Cellulose Hydrogel/Methylene Blue Host/Guest Model

pH-sensitive carboxymethyl cellulose hydrogel beads were prepared in spherical form by a suspension-crosslinking technique with epichlorohydrin as a crosslinking agent and fluid wax as the suspending solvent. The hydrogel beads are spherical in shape with a diameter of about 4mm, which exhibits reversible pH-sensitive behavior. The hydrogel beads have good behavior for adsorption and release. The ability of the hydrogel beads to uptake and release a positively charged cationic guest molecule, such as methylene blue, could be tuned by controlling the extent of carboxylate ionization via pH. At 25 degrees C, the maximum loading amount for methylene blue exceeded 1350.6g/g with 56.27% adsorption ratio.