Novel amidoxime-functionalized SBA-15-incorporated polymer membrane-type adsorbent for uranium extraction from wastewater

The reusability of adsorbents is vital in practical applications for U(VI) wastewater treatment. Herein, a precursor membrane-type adsorbent PAN/AO-SBA-15 was fabricated by blending powdered AO-SBA-15 into PAN membrane by a phase-inversion process, and a poly(amidoxime) membrane-type adsorbent (PAO/AO-SBA-15) was prepared by modifying the PAN/AO-SBA-15 membrane by an amidoximation process. The adsorption capacity of PAO/AO-SBA-15 was 4532 mg center dot m(2) at pH 6.0, which is far higher than that of PAN/AO-SBA-15 (3058 mg center dot m(2)) because PAO can provide additional adsorption sites. The pseudo-second-order and Langmuir models best describe the adsorption process. Moreover, PAO/AO-SBA-15 has better recyclability over eight regeneration cycles than PAN/AO-SBA-15. Additionally, PAO/AO-SBA-15 exhibits excellent adsorption selectivity for U(VI) in artificial wastewater containing multiple coexisting ions (Na+, K+, Mg2+, Ca2+, Mn2+, Cu2+, and Zn2+). This study suggests that blending powdered AO-SBA-15 into the membrane is an effective approach to simplify the regeneration process, and the amidoximation process of PAN/AO-SBA-15 is beneficial for improving its adsorption properties.