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

Nano zero-valent iron (Fe0) has been widely used to remove Uranium (U(VI)). In order to enhance the performance of Fe0 toward U(VI) removal, the Fe0 was assembled into graphene oxide (GO) sheets via 3-aminopropyl triethoxysilane (APTES) as Fe0/APTES-GO composites. The Fe0/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 Fe0 particles were encapsulated into rolled-up GO, which greatly improved the stability of Fe0. Batch experiment showed that only a small amount of Fe2+ was leached in the first two leaching cycles of Fe0/APTES-GO composites. The removal capacity of Fe0/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 Fe0 and an abundance of functional groups (i.e., -COOH, C-OH and -OH) on the Fe0/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-Fe0 cluster.