A pH-responsive carboxymethyl cellulose/chitosan hydrogel for adsorption and desorption of anionic and cationic dyes

A carboxymethyl cellulose/chitosan interpenetrating network hydrogel was prepared to adsorb and desorb anionic and cationic dyes applying different pH conditions. The three-dimensional network structure of the hydrogel was investigated using Scanning Electron Microscopy (SEM). Fourier Transform Infrared (FT–IR) was used to analyze the bonding mechanism of the hydrogel. The compression modulus of the hydrogel under neutral conditions exhibited an increase in parallel with the increase of carboxymethyl cellulose content. Under alkaline conditions, the swelling properties of hydrogels in water were enhanced with the increase of the carboxymethyl cellulose content. On the other hand, under acidic conditions, the swelling performance of hydrogels in water was decreased with the increase of carboxymethyl cellulose content. The adsorption capacity and desorption ratio of carboxymethyl cellulose/chitosan hydrogel for Acid Orange II were higher than 100 mg/g and 90%, respectively, while for Methylene Blue were higher than 110 mg/g and 95% even after five adsorption/desorption cycles. This study suggests that the carboxymethyl cellulose/chitosan interpenetrating network hydrogel showed different swelling behaviors under different pH values, which could present great potential as carrier materials in the controllable release-based applications.