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 4 mm, 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°C, the maximum loading amount for methylene blue exceeded 1350.6 g/g with 56.27% adsorption ratio.