Cationic cellulose hydrogels cross-linked by poly(ethylene glycol): Preparation, molecular dynamics, and adsorption of anionic dyes

• Hydrogels composed of poly(ethylene glycol) and quaternized cellulose were prepared.
• The hydrogels exhibited water-swelling behavior in solutions with a wide range of pH.
• The prepared hydrogels exhibit high adsorption ability towards anionic dyes.
• The dynamics of the hydrogels was investigated by the solid relaxation analyses.
• The hydrogels could be regenerated and proved to be recyclable adsorbents.

Cationic cellulose hydrogels (CCGs) were prepared from quaternized celluloses with degrees of substitution (DS) of 0.56, 0.84, and 1.33, by the cross-linking reaction with poly(ethylene glycol) diglycidyl ether as a cross-linker. The CCGs exhibited swelling behavior in aqueous solutions, which was not affected by pH and temperature of the solution because of the presence of quaternary ammonium groups in their structures. The CCGs showed adsorption ability toward anionic dyes in aqueous solution, which increased with increasing DS. The dye adsorption was found to follow the pseudo-second order kinetic model and the equilibrium isotherm data can be described by the Langmuir adsorption model. In addition, the CCGs could be regenerated and proved to be recyclable adsorbents for wastewater treatment.