Effective removal of hazardous cationic dye from polluted water using sulfonated copolymer hydrogel: Synthesis, nonlinear isotherm, and kinetics investigation

In this study, a novel copolymer hydrogel according to poly (acrylonitrile-co-sodium styrene sulfonate) (ASD) as an effective adsorbent was prepared via free radical polymerization of the solution at a ratio of 1:1 to remove cationic crystal violet dye (CV) from wastewater. The prepared hydrogel was thoroughly characterized using FTIR, TGA, SEM and EDX analysis. The hydrogel that was produced has a notable capacity for adsorbing cationic dye uptake over a wide pH range as well as easily separated without the need for filtration and centrifugation. Under optimal conditions using 1 g/L of hydrogel, 400 mg/L dye concentration and contact time of 5 h, the prepared hydrogel showed high dye removal efficiency approaching 100 %. The sulfonated copolymer hydrogel has a maximum adsorption capacity of 518.49 mg/g, which is six times larger than pristine PAN. The Langmuir model properly represented the isotherm adsorption data, however the kinetics data was better described by the pseudo-second-order model. Based on the calculated thermodynamic characteristics, the process of CV dye adsorption on sulfonated copolymer hydrogel surface was spontaneous and exothermic.