Preparation of Ag-Loaded Amidoxime-Functionalized Wool Fibers via Thiol-ene Click Reaction for Uranium(VI) Adsorption with Good Antibiofouling Properties

Abstract

The recovery of uranium from seawater by adsorption is strategically important for the sustainability of nuclear energy. However, marine biofouling reduces the adsorption efficiency in adsorbents of uranium(VI) ions. To develop biomass adsorbents with good adsorption capacity and antibiofouling properties, we propose a strategy to release free thiol groups by cleaving the disulfide bonds in wools and then via thiol-ene click reaction and in situ coprecipitation, preparing Ag-loaded amidoxime-functionalized wool fibers (Ag@Wool-AO) for selective adsorption of U(VI) ions. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The adsorption properties, selectivity, antibacterial properties, and reusability of Ag@Wool-AO as an adsorbent of U(VI) ions were also studied. The results showed that while the adsorption process was at 25 °C and pH 6.0 with the initial concentration of uranium ions at 50 mg/L, the adsorption capacity of Ag@Wool-AO can reach 92.49 mg/g. The adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Using the Langmuir model, we found the adsorption capacity of Ag@Wool-AO for U(VI) ions to be 172.71 mg/g. Under simulated seawater conditions, the removal rate of the U(VI) ion by Ag@Wool-AO is 33.30%. Furthermore, the loaded Ag nanoparticles imparted good antibiofouling properties to the adsorbent by providing hot electrons for the reduction of U(VI) under the action of photoactivity. The cooperation between the injected hot electrons and the U(VI) binding site directly promotes the remarkable U