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Capacitive deionization (CDI) technology holds great potential for rapid and efficient uranyl ion removal from wastewater. However, the related electrode materials still have much room for research. Herein, chitosan/phytic acid complexes were anchored on polypyrrole nanotubes (CS/PA-PPy) to fabricate the electrode for the electrosorption of uranyl ions (UO 2 2+). In this system, polypyrrole nanotubes provided specific channels for ion and electron diffusion, and chitosan/phytic acid complexes offered selective sites for UO 2 2+ binding. The results demonstrated that CS/PA-PPy via electrosorption showed faster kinetics and higher uranium uptake than those via physicochemical adsorption. The maximum adsorption capacity toward UO 2 2+ via electrosorption (1.2 V) could reach 799.3 mg g−1, which was higher than most of the reported CDI electrodes. Electrochemical measurements and experimental characterizations showed that the electrosorption of UO 2 2+ by CS/PA-PPy was a synergistic effect of capacitive process and physicochemical adsorption, in which the capacitive mechanism involved the formation of an electric double layer from hollow polypyrrole nanotubes, whereas the coordination of phosphate, amino and hydroxyl groups with UO 2 2+ was attributed to physicochemical adsorption. With the rational design of material, along with its excellent uranium removal performance, this work exhibited a novel and potential composite electrode for uranium capture via CDI from wastewater. Chitosan/phytic acid complexes were anchored on polypyrrole nanotubes to fabricate capacitive deionization electrode for the removal of uranyl ions from wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Functionalized electrospun nanofibers were applied for the uranium extraction. • Hyperbranched amidoxime groups with assistant groups were grafted. • Photothermal conversion ability was also introduced into the fibers. • The nanofiber adsorbents showed good antibacterial activity. • The uranium extraction capacity reached 9.54 mg g−1 from natural seawater. 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. [ABSTRACT FROM AUTHOR]