Nano zero valent iron encapsulated in graphene oxide for reducing uranium.

Nano zero-valent iron (Fe) has been widely used to remove Uranium (U(VI)). In order to enhance the performance of Fe toward U(VI) removal, the Fe was assembled into graphene oxide (GO) sheets via 3-aminopropyl triethoxysilane (APTES) as Fe/APTES-GO composites. The Fe/APTES-GO composites were triumphantly prepared, characterized and analyzed by means of Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) together with Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). SEM and TEM-EDS results manifested that Fe particles were encapsulated into rolled-up GO, which greatly improved the stability of Fe. Batch experiment showed that only a small amount of Fe was leached in the first two leaching cycles of Fe/APTES-GO composites. The removal capacity of Fe/APTES-GO composites was up to 1357.99 mg/g at pH = 4.1 and T = 50 °C, which was mainly attributed to the reducing activity of Fe and an abundance of functional groups (i.e., -COOH, C-OH and -OH) on the Fe/APTES-GO composites. The electrostatic potential (ESP) from the calculation also supported that U(VI) tended to be reduced at the back side of the GO-Fe cluster.