Gamma radiation-assisted synthesis and characterization of CdS-doped bio-hydrogel for ethyl violet dye removal from aqueous solution: isotherm, kinetic, and thermodynamic studies

This paper investigates the intricate synthesis methods of radiation-induced hydrogels, focusing on their structural characteristics and functional benefits. Specifically, Pectin/PVP/CdS nanocomposite hydrogels were prepared by gamma-radiation copolymerization of Pectin and Poly (vinyl pyrrolidone) (PVP) in the presence of cadmium sulphide nanoparticles (CdS NPs). The study systematically examined how the irradiation dose, the incorporation of CdS NPs, and varying Pectin/PVP ratios affect the resulting gel content and swelling properties. Comprehensive structural characterization was performed using FTIR, UV/vis, XRD, SEM, EDX, and TEM. Significantly, the prepared nanocomposite was then employed as an efficient adsorbent for removing ethyl violet (EV) dye from aqueous solutions. Results indicated that the Pectin/PVP/CdS nanocomposite exhibited a substantially higher adsorption capacity than the Pectin/PVP control, achieving up to 90 % removal efficiency under optimal conditions. Adsorption kinetics confirmed a best fit with the pseudo-second-order model, indicating that a chemical interaction is the rate-limiting step, while the process itself is exothermic and follows the Freundlich isotherm model.