PEI grafted amino-functionalized graphene oxide nanosheets for ultrafast and high selectivity removal of Cr(VI) from aqueous solutions by adsorption combined with reduction: Behaviors and mechanisms

We herein developed a facile method to prepare PEI grafted amino-functionalized graphene oxide nanosheets, which exhibit a high selectivity in capturing Cr(VI) contaminants from aqueous solutions with an ultrahigh adsorption capacity of 1185 mg/g and fast kinetics to reduce trace Cr(VI) concentrations below the allowed safe levels for drinking water defined by the WHO (0.05 mg/L) within 15 min in the presence of other coexistent ions. To the best of our knowledge, the adsorption capacity of the composites is highest among all PEI functional adsorbents reported so far. Furthermore, the cycle experiments indicated that the composites still exhibited excellent adsorption performance after 40 cycles. The adsorption-reduction mechanism of Cr(VI) on composites was further confirmed. Moreover, the separation performance of the composites was further improved by introducing magnetic nanoparticles on the surface of the composites. Finally, the composites were successfully utilized in dealing with the actual industrial effluent.