Adsorption-reduction behavior of hexavalent chromium on Fe3O4-graphene oxide surface with special implication on environmental remediation

Magnetic graphene hybrid has encouraging application in environmental remediation. Herein, adsorption-reduction behavior of Cr (Ⅵ) on Fe3O4-graphene oxide (Fe3O4-GO) surface was inspected via both theoretical and experimental methods. In the theoretical level, acidity impact on Cr (Ⅵ) species evolution and Cr (Ⅵ)→Cr (Ⅲ) reduction was investigated with the methodology of equilibrium thermodynamics. In the experimental level, adsorption fittings and spectroscopic tests (FTIR, UV–Vis, XPS) were performed to clarify the adsorbent-adsorbate interaction. Results indicate: (1) Under acidic condition, Cr (Ⅵ) is adsorbed by Fe3O4-GO in the form of H2CrO4. Afterwards, over three-fifths of H2CrO4 is reduced to Cr (Ⅲ), reaching adsorption percent and quantity 95.53 % and 382.10 mg g−1 in 10 min (2) Under basic condition, Cr (Ⅵ) is adsorbed in the form of CrO42− without reduction. In the context of environmental remediation, two special implications are thereby procured. (1) Under acidic condition, Cr (Ⅵ) removal efficiency at the first cycle is maximized, while magnetic recovery is deteriorated, resulting in unsatisfactory cyclic performance. (2) Under basic condition, Cr (Ⅵ) removal efficiency is inferior to that under acidic condition, while magnetic recovery is guaranteed, leading to satisfactory cyclic performance. Exploration of this work provides reference especially for developing Fe3O4-GO architecture towards efficient sequestering of hexavalent chromium.