Co-irradiation induced graft polymerization of pre-swollen polyacrylonitrile nanofiber membranes for uranium extraction from seawater

Abstract

A widely adopted approach in the field of adsorbent preparation for uranium extraction involves grafting acrylonitrile onto inert polymer substrates, followed by amidoximation. However, the low utilization ratio of the monomer acrylonitrile results in elevated synthesis costs and complications during post-processing, limiting the industrial application of graft polymerization techniques for developing high-capacity uranium extraction materials from seawater. In this study, a high molecular weight polyacrylonitrile (HMWPAN) nanofiber membrane was utilized to prepare an economically efficient and high-performance material for uranium extraction via a pre-swollen and co-irradiation-induced graft polymerization technique. Research demonstrates that after 24 hours of adsorption in a uranyl ion(VI) solution, the material achieves an adsorption capacity of 483.82 mg_U g_ads⁻¹. In natural seawater, following 50 days of exposure, the uranium adsorption capacity reaches 8.32 mg_U g_ads⁻¹. Meanwhile, by utilizing the pre-swollen simultaneous co-irradiation-induced grafting technique, the monomer utilization ratio of the HMWPAN nanofiber membrane reached 83.02%, significantly outperforming conventional methods. The method offers several advantages, including high monomer utilization, simplified post-processing, excellent material performance, and minimal homopolymer formation, all of which contribute to reduced production costs. Moreover, the high level of automation in the pre-swollen and co-irradiation-induced graft polymerization process makes it well suited for continuous production. The synthesis and preparation methods employed in this study provide new perspectives for advancing the industrialization of uranium extraction from seawater.