Chitosan-g-poly (styrene sulfonate) hydrogel with crosslinked polymeric for the efficient remediation of cationic dyeing wastewater

Adsorbents with high adsorption capacities, environmental sustainability, and reusability are increasingly in demand for wastewater treatment applications. This study outlines the synthesis of a sulfonated hydrogel composed of poly (styrene sulfonate)-grafted chitosan (CS), fabricated through free radical polymerization, for the efficient adsorption of cationic dyes. The prepared hydrogel was characterized in terms of its chemical composition, morphological features, and thermal stability. The adsorption performance was tested under various experimental conditions. The optimal adsorption was achieved with a sulfonated hydrogel using a CS/styrene sulfonate mass ratio of 1:2, resulting in a maximum adsorption capacity of 394 mg/g under alkaline conditions. Kinetic and isotherm analyses indicated that the adsorption behavior follows the pseudo-second-order and Langmuir models, respectively. Additionally, the sulfonated CS hydrogel exhibited selective adsorption for cationic dyes and maintained consistent adsorption capacities across eight adsorption-desorption cycles after regeneration. These findings position the sulfonated CS hydrogel as a promising candidate for wastewater treatment and advanced separation technologies.