Synthesis of an efficient adsorbent hydrogel based on biodegradable polymers for removing crystal violet dye from aqueous solution

Water pollution with toxic dyes threatens human health world-wide. Herein, we prepared an effective adsorbent hydrogel for removing toxic cationic crystal violet (CV) dye from its aqueous solutions using biodegradable polymers such as; xanthan gum (XG) and poly (N-vinyl imidazole) (PVI). The structure and morphology of the prepared XG/PVI hydrogel and CV loaded hydrogel were characterized by FTIR, FE-SEM and XRD, while thermal stability of investigated hydrogel was characterized by TGA. Adsorption experiments were carried out as functions of initial concentration of CV dye, the adsorbent dose, pH of solution, temperature, and contact time. Results were analyzed using Langmuir and Freundlich isotherm models. It is found that the data were well fitted by Langmuir model. The maximum adsorption capacity achieved was found to be 453mgg(-1) due to electrostatic, H-bonding and dipole-dipole interactions between adsorbent surface and CV molecules. The adsorption kinetic studies showed that the adsorption followed pseudo-first order and intraparticle diffusion kinetic models. Regeneration (desorption) studies showed that XG/PVI hydrogel is an interesting adsorbent for removing toxic dyes from waste water.