A new family of actinide sorbents with more open porous structure: Fibrous functionalized silica microspheres

No one could have failed to notice the fact that the basic research on the separation of nuclear fuel associated radionuclides is currently a hot topic as a result of the universality of nuclear industry. Herein, a kind of fibrous mesoporous silica microspheres and its derivatives tailored by amine (APS-F-SiO2), carboxyl (COOH-F-SiO2), phosphate (DPTS-F-SiO2) and amidoxime (AD-F-SiO2), respectively, were successfully fabricated for high efficient U(VI) capture from aqueous solution. The synthesized sorbents were well characterized by SEM, FT-IR, N-2 sorption-desorption measurement and TGA, which confirms achievement of the functionalization. The U(VI) sorption onto these microsphere sorbents was then explored in detail. The results clearly show that these microsphere materials especially APS-F-SiO2 and COOH-F-SiO2 are indeed effective U(VI) sorbents, in terms of considerable sorption capacity of similar to 200 mg/g, the short equilibrium time of less than 30 min, the ionic strength-independent nature, and desirable selectivity towards U(VI) over a range of competing ions. Moreover, the sorbed U(VI) ions can be easily desorbed from the sorbents by controlling a lower pH, e.g. pH 1.0, and the reclaimed sorbent can be reused without obvious reduction of U(VI) uptake even after 4 sorption-desorption cycles, implying an excellent stability and reusability of the sorbents. These sorbents also keep high performance in U(VI) sorption even following 400 kGy gamma irradiation in water, which further highlights the opportunity for this kind of materials in radionuclide separation. The finding of the present work offers new platform for developing actinide sorbents applied in various practical cases.