Poly(acrylic acid)-grafted xanthan gum xanthate as reusable adsorbent for the removal of Cu(II) and Co(II) ions from aqueous solutions

Abstract

This article focuses on the development of a xanthan gum xanthate-based hydrogel (XGX-g-PAA hydrogel) by grafting poly(acrylic acid) onto XGX using free radical polymerization technique. The synthesized hydrogel has been used for the removal of potentially toxic elements from synthetic wastewater. The hydrogel has been characterized by UV, FTIR, XRD, SEM-EDS, TGA, GPC, and PZC techniques. The pore size, pore volume, and surface area of the hydrogel were analyzed via BET analysis. The hydrogel showed % maximum swelling of 26375.5%, 25,733%, and 24731.54% in distilled water, tap water, and gray wastewater for 42 h. Highest removal efficiencies of 93.31% (for Cu(II) ions) and 91.51% (for Co(II) ions) with maximum adsorption capacities (q_m) of 373.13 mg/g (for Cu(II) ions) and 299.401 mg/g (for Co(II) ions) were observed for the synthesized XGX-g-PAA hydrogel for an optimum time duration of 150 min. The pseudo-second-order kinetics and Langmuir adsorption isotherm models have been found to fit adequately with the experimental data. The XGX-g-PAA hydrogel can be reused up to five consecutive adsorption–desorption cycles. Hence, the synthesized hydrogel has been found to be an effective adsorbent that can be utilized for the treatment of real wastewater like lignin-enriched paper industry wastewater (LEPIW).