Facile synthesis of XGX-based hydrogel and its application for the removal of heavy metal ions from aqueous solutions

The present study focuses on the use of Xanthan Gum xanthate-based hydrogel (XGX-g-PAM) obtained via free radical polymerisation of poly(acrylamide) on the surface of Xanthate of Xanthan Gum as a novel adsorbent for the efficient removal of heavy metal ions from synthetic wastewater. Four grades of hydrogel have been synthesized in all viz. XGX-g-PAM G-1, XGX-g-PAM G-2, XGX-g-PAM G-3, and XGX-g-PAM G-4 hydrogel. The hydrogel was characterized using various techniques like UV, FT-IR, SEM, XRD, GPC, TGA and ΔpH_PZC analysis. The maximum swelling ratios (SR) of the prepared XGX-g-PAM G-3 hydrogel has been found to be 303.8, 275.35 and, 258.455 g/g in 1215 min for distilled water, tap water and grey wastewater. Furthermore, the water retention ratio (% WRR) for XGX-g-PAM G-3 is found to be 78.62%, 79.19% and, 80.95% for distilled water, tap water and, grey wastewater respectively after 1800 min. This shows that the hydrogel has an excellent swelling and water retention capacity. The concentration of Cu²⁺ and Co²⁺ ions in aqueous solutions has been determined spectrophotometrically with the help of a UV–visible spectrophotometer. The highest removal of 94.85% and 93.25% and maximum adsorption capacities of 312.5 mg/g and 281.69 mg/g were observed with the XGX-g-PAM G-3 hydrogel for Cu²⁺ and Co²⁺ ions, respectively. Further experiments were performed at varying adsorbent dosage, pH, time of contact, temperature, and concentration. Experimental findings suggest that the newly synthesized XGX-g-PAM hydrogel acts as an effective adsorbent for the removal of Cu²⁺ and Co²⁺ ions from aqueous solutions. Hence, the developed adsorbent has an excellent potential for the treatment of industrial wastewater containing toxic metal ions.