Amidoxime Functionalized Mesoporous SBA-15 with Various Mesostructures for Highly Efficient Concentration of U(VI)

Many current sorbents are limited for U(VI) concentration from aqueous solutions due to their inappropriate structures and surface chemistry. Herein, we report the rapid sorption of U(VI) with high capacities and selectivity by amidoxime modified ordered mesoporous SBA-15 with two typical morphologies (i.e., rods and plates) via a post-grafting method. Variables of the geochemical conditions (contact time, pH value, initial concentration, temperature and coexisting metal ions) are investigated. The results show that the mesostructures including morphologies and pore length of SBA-15 perform the dominant function for the fast sorption kinetics (10 min for plates, 20 min for rods), while the modified amidoxime groups make the excellent U(VI) sorption capacities (646.2 mg . g (-1) for plates, 499.8 mg . g (-1) for rods at pH 5.0 and T 298.15 K) and high selectivity possible. U(VI) adsorbed amidoxime-functionalized SBA can also be effectively regenerated by HCl solutions and reused well after six cycles.