Journal
RSC ADVANCES
Volume 4, Issue 106, Pages 61919-61926Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c4ra09541c
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Funding
- National Natural Science Foundation of China [21207135, 21207136, 91126020]
- National 863 Plan [2011AA10A10401]
- Hefei Center for Physical Science and Technology [2012FXZY005]
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Graphene oxide-supported chitosan (GO-Ch) composites were synthesized using a covalent method for U(VI) adsorption and were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA) and extended X-ray absorption fine structure (EXAFS). The characteristic results indicated that Ch was successfully grafted onto GO. The adsorption of U(VI) on GO-Ch was investigated under different environmental conditions. The adsorption kinetics showed that the adsorption of U(VI) on GO-Ch followed the pseudo-second-order equation. The maximum adsorption capacity of U(VI) on GO-Ch at pH 4.0 and T = 303 K calculated from the Langmuir model was 225.78 mg g(-1). Thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that U(VI) adsorption on GO-Ch was an endothermic and spontaneous process. The batch desorption indicated U(VI) cannot be completely desorbed from GO-Ch without intervention, suggesting the irreversible adsorption of U(VI) on GO-Ch. The analysis of FT-IR spectra suggested that the interaction mechanism of U(VI) on GO-Ch was mainly chemical adsorption by -NH2 and -COOH groups. According to EXAFS analysis, the peaks at similar to 2.9 angstrom can be satisfactorily fitted by the U-C/N shell, revealing the formation of inner-sphere surface complexes. It is demonstrated that the GO-Ch nanocomposite can be a promising material for the preconcentration and solidification of U(VI) from large volumes of aqueous solution.
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