Uranium extraction performance in uranium-spiked simulated seawater and natural seawater. (A) Structural diagram of uranium extraction unit for evaluating uranium adsorption performance. SWTC-PAO sponge is fixed inside the uranium extraction unit by placing it onto the porous support plate. (B) Uranium extraction capacity of SWTC-PAO sponge under different pH. (C) Uranium adsorption kinetics of SWTC-PAO sponge under different initial uranium concentrations in simulated seawater. (D) Morphology of SWTC-PAO sponge after being used for uranium adsorption in simulated seawater. (E) Reusability of SWTC-PAO sponge. (F) Extraction kinetics of SWTC-PAO sponge for uranium in filtered natural seawater.