High-Performance\nPolyamidoxime Porous Membrane Prepared\nby the In Situ Modification/Nonsolvent-Induced Phase Separation Strategy\nfor Uranium Extraction from Seawater

The abundance of uranium (U(VI)) reserves in seawater\nmakes it\ncrucial to develop economically efficient methods for uranium extraction\nfrom seawater. In this work, an enhanced polyamidoxime porous membrane\n(PAOM) was fabricated by pre-in situ amidoxime modification combined\nwith nonsolvent-induced phase separation (NIPS). The strategy of in\nsitu modification of the polyacrylonitrile (PAN) solution served to\nenhance the homogeneity of the reaction and avoid the destruction\nof the membrane matrix and pore structure. Compared with the control\nsample (AOPM), PAOM possessed better mechanical strength and hydrophilicity.\nThe introduction of polyvinylpyrrolidone (PVP) formed a porous structure\nin PAOM, improving spatial accessibility and facilitating the diffusion\ntransport and capture of UO<sub>2</sub><sup>2+</sup> inside the membrane.\nThe more uniform and abundant distribution of amidoxime groups in\nPAOM gave it ultrahigh adsorption capacity and selectivity. The equilibrium\nadsorption capacity and <i>K</i><sub>d</sub> value of PAOM\nwere 1.72 and 5.51 times higher than those of AOPM. Meanwhile, PAOM\nalso demonstrated good recyclability, with only a 6.15% decrease in\nadsorption capacity after seven cycles. Additionally, PAOM exhibited\nexcellent dynamic adsorption performance, and after 14 days of continuous\nfiltration and adsorption, PAOM could extract 2.03 mg·g<sup>–1</sup> U(VI) from natural seawater.