Ammonium thiocyanate functionalized graphene oxide-supported nanoscale zero-valent iron for adsorption and reduction of Cr(VI)

In this study, ammonium thiocyanate functionalized graphene oxide (ATGO)-supported nanoscale zerovalent iron composite (ATGO-nZVI) employed to extract Cr(VI) from aqueous solution, was successfully synthesized by chemical oxidative polymerization and sodium borohydride reduction method. Characteristics of X-ray diffraction and high-resolution transmission electron microscopy confirmed the high disperse and activity of nZVI after supported by ATGO. Batch experiments showed that the removal efficiency of ATGO-nZVI was higher than that of bared nZVI and ATGO. Furthermore, the stability of ATGO-nZVI composite was higher than that of nZVI, which was proved by the Tafel polarization curves. Dynamic experiments suggested that the removal process was confirmed to be in agreement with not only the pseudo-second-order model for adsorption but also Langmuir-Hinshelwood first-order model for reduction process, which revealed that the removal of Cr(VI) by ATGO-nZVI composite was dominated by chemical surface-limiting step. Considering the experiments and characterization, the removal mechanism containing rapid adsorption of Cr(VI) onto the ATGO-nZVI surface and reduction by nZVI was clarified. The above results suggested that ATGO-nZVI would become a promising remediation material for Cr (VI) pollution cleanup. (C) 2020 Elsevier Inc. All rights reserved.