Synthesis of amidoximated graphene oxide nanoribbons from unzipping of multiwalled carbon nanotubes for selective separation of uranium(vi)

Abstract

A kind of uranium-selective sorbent has been studied using graphene oxide nanoribbons (GONRs) from the unzipping of multiwalled carbon nanotubes as a solid matrix and amidoxime (AO) as a functional group. Amidoxime-functionalized GONRs (AOGONRs) were successfully prepared by chemical grafting technology and characterized by scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis and X-ray photoelectron spectroscopy. The as-prepared AOGONRs were applied to adsorb U(VI) from aqueous solutions and exhibited a high sorption capacity towards U(VI) due to the strong chelation of AO to U(VI). It can be noted that the uranium sorption on the AOGONRs was pH-dependent, ionic strength-independent, fast, endothermic, spontaneous and a pseudo-second order process. The U(VI) sorption amount reached up to 2.112 mmol g⁻¹ (502.6 mg g⁻¹) at pH = 4.5 and T = 298 K. The sorption study performed in a simulated nuclear industry effluent demonstrated that the new sorbent had a desirable selectivity towards U(VI) ions over a range of competing metal ions. The results suggest that AOGONRs may be a potential and suitable candidate for the separation of U(VI) from various uranium-containing water samples.