Effect of ternary polymer composites of macroporous adsorbents on adsorption properties for heavy metal removal from aqueous solution.

This research is focused on the preparation of macroporous poly(vinyl alcohol) (PVA)/chitosan (CS)/AlO adsorbents for removal of residual metal ions from wastewater. The PVA/CS/AlO adsorbents were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and energy dispersive X-ray (EDX) techniques to confirm that all compositions were incorporated into the PVA/CS/AlO adsorbents without chemical modification. Furthermore, a comparison of the properties of the PVA/CS/AlO adsorbents suggested that PVA/CS/0.50AlO was the most suitable sample for adsorption study. The adsorption properties of PVA/CS/0.50AlO for the removal of metal ions such as Pb, Cu, Zn, and Ni in aqueous solution adsorbents in both single and quaternary systems were investigated. The results show that the adsorption selectivity of the PVA/CS/0.50AlO adsorbent for these metal ions was provided in the following order: Pb  > Cu  > Zn  > Ni. The adsorption isotherm was studied by equilibrium data obtained from batch experiments. It was found that the Freundlich isotherm model was suitable for explaining the adsorption process. Adsorption kinetics were studied, which indicated that the adsorption of Pb, Cu, and Zn followed a pseudo-second-order kinetic model, while the adsorption of Ni followed a pseudo-first-order kinetic model. In addition, adsorption-desorption cycles were studied to prove the reusability of PVA/CS/0.50AlO adsorbents. The PVA/CS/0.50AlO adsorbents were able to be regenerated and reused. In a continuous adsorption process, a column experiment was simulated in laboratory. The results showed that Cu was the most selective for a fixed-bed column. Thus, PVA/CS/0.50AlO adsorbents could be potential used for toxic metal ion removal from wastewater, in both batch and fixed-bed continuous-flow columns.