Enhanced and selective uranium extraction onto electrospun nanofibers by regulating the functional groups and photothermal conversion performance

Abstract

Uranium extraction from natural seawater is critical to addressing the shortage of uranium resources, but it is a giant challenge. The amidoxime-based adsorbent is regarded as one of the most promising materials for uranium capture, whereas still suffers from low adsorption site utilization and poor selectivity toward U(VI) against V(V). Herein, hyperbranched amidoxime group grafted photothermal electrospun fibers (AOPEI-C-PAN fibers) were reported for highly efficient uranium extraction from seawater. Carbon nanotubes (CNTs) were blended into the electrospun fibers to introduce the photothermal character. Hyperbranched grafting could improve the content of the amidoxime group and bring an assistant group (the amine group). Owing to the large content of functional groups, synergetic coordination interaction and photothermal conversion ability, the novel fiber adsorbents realized a fast adsorption rate (shortening the equilibrium time to 36 h from 60 h compared with the dark condition), high uranium uptake (1738.5 mg g−1 from the Langmuir model) from the uranium spiked seawater and excellent selectivity in U/V binary system (selectivity coefficient = 85.8). Furthermore, Ag nanoparticles could also be loaded onto the CNTs to endow the fibers with antibacterial activity, thereby preventing biofouling. As a result, the uranium extraction capacity of the fiber adsorbent reached 9.54 mg g−1 after 28 days’ simulated sunlight irradiation of contact with circular seawater, which is 62.0 % higher than that under dark condition. This study reveals that AOPEI-C-PAN fiber adsorbent holds great potential in practical uranium extraction applications.