Adsorption of Methylene Blue on Hemicellulose-Based Stimuli-Responsive Porous Hydrogel

A stimuli-responsive porous hydrogel was synthesized from wheat straw hemicellulose using CaCO3 as the porogen, and its application for the removal of methylene blue was studied. The porous structure of the prepared hydrogel was confirmed by SEM analysis. The effects of pH and polyelectrolyte on the swelling of the hydrogels were discussed, and the porous hydrogels showed excellent sensitivity to pH and salt. The deswelling kinetic study indicated that the hydrogels exhibited rapid shrinking in NaCl aqueous solutions. The methylene blue adsorption on the hydrogels was investigated, and the obtained adsorption data was fitted to the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics models, and the pseudo-first-order kinetic model could describe the adsorption process, and the adsorption process of methylene blue on the hydrogels was controlled by external film diffusion. This study reported that the hemicellulose-based porous hydrogel is promising for water treatment. (C) 2014 Wiley Periodicals, Inc.