[Preparation and Pb²⁺ Electrosorption Characteristics of Graphene Hydrogels Electrode]

Electrosorption has the advantage of high adsorption capacity and electrode regeneration in the removal of heavy metal ions in water. In this study, graphene hydrogels (GS) were prepared by hydrothermal reduction of graphene oxide (GO) suspensions and the electrode was obtained via compression of GS. Various electrochemical properties of GS were tested. The kinetics and thermodynamics of the electrosorption of Pb²⁺ on GS electrode and GS electrode reusability were investigated. The results showed excellent capacitive behavior (200.4 F·g^-1 at 1 A·g^-1) of GS. The electrosorption performance of GS indicated that high voltage was favored for the removal of Pb²⁺ and the highest removal efficiency reached 96.4% when the voltage value was -1.2 V. The electrosorption capacity for Pb²⁺ removal was found to be 461.20 mg·g^-1, which was twice as high as the saturated adsorption capacity of GS. The GS electrode could regenerate after electrosorption when the voltage value was+1.2 V and the removal efficiency of Pb²⁺ was still maintained above 95% after electrosorption-desorption for 15 cycles.