# Facile Preparation of Graphene Oxide-MIL-101(Fe) Composite for the Efficient Capture of Uranium
## 4 Conclusions  
To conclude, the GO-MIL-101(Fe) sandwich composite was synthesized through a facile in situ growth method. By changing the amount of GO precursors, the size and distribution density of MIL-101(Fe) in the composites were easily tuned. Notably, batch adsorption experiments showed that GO-15-MIL-101(Fe) possessed superior adsorption performance with enhanced adsorption efficiency and improved adsorption capacity (106.89 mg g\({}^{-1}\) at pH = 5.5, T= 298 K) compared with raw MIL-101(Fe) (68.93 mg g\({}^{-1}\) at same condition). The uptake of U(VI) by GO15-MIL-101(Fe) was realized through the inner-sphere surface complexation as well as electrostatic interaction. FT-IR and XPS analysis illustrated the importance of the synergistic effect between GO nanosheets and MIL-101(Fe) octahedrons on the resultant adsorption performance. Moreover, the good reusing capability of GO15-MIL-101(Fe) indicated the application potential of such a composite material. Therefore, this work provided an effective route to design advanced composite adsorbents with satisfying radionuclide uptake ability by giving play to the functionality of individual components.  
**Supplementary Materials:** The following are available online at [[http://www.mdpi.com/2076-3417/8/11/2270/s1](http://www.mdpi.com/2076-3417/8/11/2270/s1)]([http://www.mdpi.com/2076-3417/8/11/2270/s1](http://www.mdpi.com/2076-3417/8/11/2270/s1)), Table S1: Composition of groundwater and surface water used to eValuate the adsorption of U(VI) on GO15-MIL-101(Fe), Figure S1: XRD pattern of as-prepared MIL-101(Fe) and GO-MIL-101(Fe) composite, Figure S2: Nitrogen adsorption-desorption isotherm and pore size distribution of (a) and (b) MIL-101(Fe), (c) and (d) GO15-MIL-101(Fe), Table S2: Summary of surface area and pore volume obtained from N\({}_{2}\) adsorption isotherms, Figure S3: The adsorption efficiency of GO15-MIL-101(Fe) towards U(VI) at different initial U(VI) concentrations (0.035 mg L\({}^{-1}\), 1.3 mg L\({}^{-1}\), 3 mg L\({}^{-1}\) and 10 mg L\({}^{-1}\)). The inset numbers represent the adsorbent dosage, Figure S4: U(VI) speciation based on Visual MINTEQ program in the experimental adsorption solution ([U(VI)] = 10 mg L\({}^{-1}\), I = 0.01 mol L\({}^{-1}\) (NaNO\({}_{3}\)), and T = 25 \({}^{\circ}\)C), Table S3. Comparison of the adsorption efficiency of GO15-MIL-101(Fe) and MIL-101(Fe) under different coexisted ions with that in the absence of these ions, Figure S5: The adsorption efficiency of GO15-MIL-101(Fe) towards U(VI) in deionized water (pH = 5.5), simulated surface water (pH = 7.9) and simulated groundwater (pH = 8.0) at T = 298 K, and C\({}_{0}\) = 10 mg L\({}^{-1}\), adsorbent concentration = 0.2 g L\({}^{-1}\), Table S4: Comparison of the adsorption capacity of GO-MIL-101(Fe) composite towards U(VI) with other adsorbents, Figure S6: The plot of lnK\({}_{0}\) to 1/T of U(VI)adsorption onto GO15-MIL-101(Fe). Figure S7: The morphology of regenerated composite sample after 4 cycles, scale bar = 1 \(\upmu\)m.  
[PERSON] conceived the project. [PERSON] conducted the experiment and performed the measurements with help from [PERSON] and [PERSON]. Data analysis were carried out by [PERSON] and [PERSON]. All the authors discussed the results and commented on the manuscript.  
This research was funded by the National Natural Science Foundation of China (21703064) and the Fundamental Research Funds for the Central Universities (2017 MS046).  
The authors wish to thank the National Natural Science Foundation of China and Ministry of Education of the People's Republic of China for the funding support.  
The authors declare no conflict of interest.