LAUSR

Abstract A dual network Poly(Acrylamide-co-Acrylic Acid)/Xanthan Gum (XG) hydrogel incorporated with graphene oxide (GAMAAX) was synthesized through free radical polymerization method for the removal of heavy metal ions. The GAMAAX hydrogel was characterized by Fourier transform infrared spectrum (FTIR), environmental scanning electron microscope (ESEM), energy dispersive X-ray spectroscopy (EDS) and rheology tests. The adsorption capacity and electrical conductivity of GAMAAX hydrogel was investigated for varying pH range and adsorption dosage by central composite design (CCD) method. The results indicated that the heavy metal ion adsorption followed the pseudo-second-order kinetic model, and conformed Freundlich adsorption model with substantial adsorption capacities of 312.15 mg/g and 185.0 mg/g for Cd2+ and Ni2+, respectively. In addition to a great single-ion affinity for Cd2+ and Ni2+ ions, it also proved a remarkable dual-ion adsorption capability with the adsorption of 259.25 mg/g and 80.75 mg/g Cd2+ and Ni2+, respectively. Moreover, less than 20% reduction in the adsorption capacity after four adsorption–desorption cycles, verified the reusability of the GAMAAX hydrogel for the practical and large-scale wastewater treatment applications.