Preparation of amidoxime functionalized SBA-15 with platelet shape and adsorption property of U(VI)

A novel amidoxime (AO) functionalized SBA-15 (AO@SBA-15) with platelet shape and short channels, was prepared by the amidoximation reaction of hydroxylamine with cyanoethyl (CN) functionalized SBA-15 (CN@SBA-15) under N2 atmosphere. The precursor CN@SBA-15 was initially synthesized by co-condensation of tetraethoxysilane with 2-cyanoethyltriethoxysilane (CTES) using a triblock copolymer (P123) as a structural directing agent in acid medium or via the post-grafting of CTES onto SBA-15 with short channels. The AO@SBA-15 with platelet shape and short channels was employed as an adsorbent to remove U(VI) from an aqueous solution. The g-AO@SBA-15 (precursor prepared by post-grafting method) has higher adsorption capacity (625 mg g−1) than that of c-AO@SBA-15 (precursor prepared by co-condensation method) (516 mg g−1) at an optimum pH of 6, but with one more preparation step. Results indicated that both the adsorbents showed fast adsorption rate, high selectivity to Na+, K+, Mg2+, and Ca2+, and reusability for uranium extraction. Therefore, AO-functionalized SBA-15 with short channels is a promising adsorbent to remove uranium ion from an aqueous solution.