Adsorption of Cd2+ and Ni2+ from Aqueous Single-Metal Solutions on Graphene Oxide-Chitosan-Poly(vinyl alcohol) Hydrogels.

ABSTRACT

The applications of graphene-based adsorbents were limited because of their complicated manufacturing technology and hi cost, thus it is very important to prepare new inexpensive and easily manufactured graphene-based adsorbents. Herein, novel GCP hydrogels with different graphene oxide (GO), chitosan (CS), and poly(vinyl alcohol) (PVA) ratios were facilely prepared through a method of freeze-thaw physical cross-linking, which was green and low-cost, and the structural characterization and adsorptive property of the optimum GCP124 hydrogel toward Cd2+ and Ni2+ in wastewater was evaluated. It was found that the GCP124 hydrogel had good mechanical strength and a special 3D interconnection porous structure. The isotherms of adsorption used the Langmuir model, and the kinetics of adsorption following the pseudo-second-order model were confirmed. Moreover, the adsorption property with respect to Cd2+ and Ni2+ in wastewater has been largely effected by the pH and was less influenced by the ionic strength and humic acid, and the GCP124 hydrogel possessed excellent adsorptive and recyclable properties. These results demonstrated that the GCP124 hydrogel could serve as a desirable adsorbent to get rid of heavy metal ions in sewage.