Quaternized polyethyleneimine-polyacrylonitrile crosslinked membrane with excellent performance synthetized by homogeneous strategy for efficient uranium extraction from seawater

The efficient extraction of uranium (U(VI)) from seawater has been a significant challenge for the nuclear industry. In this study, we prepared a robust quaternized polyethyleneimine-polyacrylonitrile crosslinked membrane (QPEI-PAN) using homogeneous cross-linking reaction and quaternary ammonium salt functionalization. PEI was uniformly dispersed inside the membrane by cross-linking with PAN molecular chains, providing QPEI-PAN with a robust structure and abundant active sites for U(VI) capture. The batch adsorption data obtained for QPEI-PAN modelled well using the Langmuir adsorption isotherm, and the maximum theoretical adsorption capacity was determined as 8198.2 mg·m⁻². Particularly, QPEI-PAN reached a maximum dynamic adsorption capacity of 6823.1 mg·m⁻² within 90 min. The robust membrane structure allowed for efficient regeneration, with a U(VI) recovery rate of 88 % over seven adsorption-desorption cycles. Quaternary ammonium salt functionalization not only gave the QPEI-PAN membrane an excellent anti-biofouling ability but also modified its surface charge, making it more suitable for the marine environment, where its adsorption capacity in unfiltered seawater (containing bacteria and microorganisms) was only 5.6 % lower than that of the filtered seawater. These findings suggest that this novel, anti-biofouling membrane-type adsorbent has significant potential for application in the field of uranium extraction from seawater (UES).