Synthesis of Xanthan/Itaconic Acid/Clay Composite and Its Structural Analysis and Performance on Copper (II) Ions Adsorption from Aqueous Solution

In this study, novel xanthan-graft-itaconic acid (XG-g-IA/clay) composites hydrogels were synthesized by the incorporation of three types of clay (montmorillonite, bentonite, and kaolinite) for adsorption of Cu2+ from aqueous solution. The results of the spectroscopy of the infrared Fourier transform before and after the adsorption process proved the contribution of clay and monomer of itaconic acid to the composite hydrogel. It also showed that carboxylate groups play a significant role in absorbing copper cations from aqueous solutions. The results of SEM results showed that the nonuniform structure of the adsorbent surface became smoother after the absorption of copper cations. The Intercalation of the nanoparticles in the polymer matrix and increasing the surface area were determined by X-ray diffraction and BET tests, respectively. The isotherm results showed that the equilibrium data followed Langmuir isotherm with the maximum adsorption capacity of 133.62, 131.96 and 125.68mg/g for XG-g-IA/BT, XG-g-IA/MMT and XG-g-IA/KT hydrogel composites at 45°C and pH=5, respectively. The experimental data of all three synthesized hydrogels were fitted well with the second-order kinetic model. The negative values of standard Gibbs free energy and the positive values of standard entropy confirmed that the adsorption process is spontaneous and feasible, respectively.