Removal of Vanadium(IV) Ions from Aqueous Solution by Graphene Oxide

摘要

Vanadium is a long-confined contaminant. In this study, graphene oxide (GO) was synthesized by the modified Hummers' method and used to remove vanadium(IV). The adsorption isotherms and kinetics of vanadium(IV) on GO at pH 2.5 and three temperatures are measured in batch experiments. The influences of ionic strength is investigated and the regeneration of GO is evaluated by washing with HCl. The results show that the adsorption isotherm corresponds to Temkin model with an adsorption capacity of 70.56 mg/g at 298 K, while the kinetic process coincides with pseudo-second-order model and approaches to equilibrium in 6 h. The adsorption capacity of GO is not influenced by Na~+ ionic strength, but sharply inhibited by Ca~(2+). The superior adsorption is dominated by electrostatic interaction, coordination bonding, and hydrogen bonding. Moreover, the GO is reusable, as shown by maintaining 53.4% of the initial efficacy after five sequential adsorption-desorption cycles.