Adsorption of Cu2+ and Ni2+ from Aqueous Solution by Arabinoxylan Hydrogel: Equilibrium, Kinetic, Competitive Adsorption

In this work, arabinoxylan-graft-acrylic acid (AX-g-AA) hydrogel was prepared and used as an adsorbent to remove and recover Cu2+ and Ni2+ from aqueous solutions. The influences of pH, ligand content on the adsorption capacity of the hydrogel, adsorption equilibrium, and kinetic were studied in detail. The competitive adsorption and recovery of heavy metal ions, regeneration and reusability of the hydrogel were present. Furthermore, the relationship between the physiochemical properties of the adsorbent and its adsorption performance was also studied. The results showed that a more expanded network favored the diffusion and adsorption of metal ions. Cu2+ and Ni2+ uptake by this hydrogel was pH and concentration dependent with the maximum loading of 330.1mg/g for Cu2+ and 248.7mg/g for Ni2+. The pseudo-second-order kinetics suggested that the ion exchange process was chemisorption-controlled. The Langmuir equation could well describe the isotherm data. Cu2+ and Ni2+ adsorbed on the hydrogel could be effectively recovered in a diluted HNO3 solution (0.01M) in 30min. AX-g-AA hydrogel also exhibited highly efficient reusability, and thus could be used repeatedly.