Adsorption-reduction synergistic effect for rapid removal of Cr (VI) ions on superelastic NH2-graphene sponge

Eliminating the environmental risks of Hexavalent Chromium (Cr (VI)) in aqueous environment was of great importance. Herein, we developed a flexible one-pot approach to synthesize novel amino-functional graphene sponge adsorbents (AFGS), in which graphene nanosheets assembled into 3D network on melamine sponge skeletons with the assistance of ethylene diamine. Benefiting from the functionalization of amino groups, AFGS showed outstanding adsorption capacity (166.46 mg g-1) because of the strong affinity with Cr (VI). Moreover, AFGS could reduce Cr (VI) into less toxic Cr (III) in low pH. The adsorption-reduction mechanism of Cr (VI) on AFGS was investigated in-depth via L-edge X-ray adsorption spectra and XPS spectra. The excellent mechanical strength, structural stability and cycling performance verified the potential of AFGS adsorbents in treating chromium containing wastewater.