Adsorption property of Rhodamine 6G onto chitosan-g-(N-vinyl pyrrolidone)/montmorillonite composite

A series of chitosan-g-(N-vinyl pyrrolidone)/montmorillonite hydrogel composites were synthesized by in situ intercalative polymerization. The properties of the composites were investigated by FTIR, XRD, scanning electron microscopy and differential scanning calorimetry. The morphologies of the hydrogel composites were sponge like with a homogeneous structure. The effects of clay on the swelling, morphology, glass transition (Tg), and water structure were studied. The swelling of the hydrogel composites formed was found to be affected by the pH of the medium and the electrolyte. Maximum swelling was observed in the hydrogel containing low percentage of clay (H-0.2) and was used to investigate the adsorption of a water soluble cationic dye Rhodamine 6G (Rh6G). The results show that the adsorption capacity for the dye increased with increase in dose, contact time but there was no change observed with respect to increase in temperature. The adsorption kinetics of Rh6G followed Pseudo second order model and the equilibrium data was found to fit Freundlich model.