Marangoni-driven hierarchically self-assembled PAO/PVA membrane for uranium extraction from seawater. (a) Scanning electron microscopy (SEM) images of SSP and SSPP membranes. The air contact surface, cross-section and water contact surface are shown. (b) Photograph images of SSP and SSPP before and after uranium adsorption, as well as mechanism diagrams of salt shrinkage resistance of SSP and SSPP membranes. (c) Stress-strain curves of SSPP membranes with different PVA contents. (d) Uranium adsorption kinetics of the SSPP₁₀ membrane. (e) Uranium desorption kinetics of the SSPP₁₀ membrane. (f) Reusability of the SSPP₁₀ membrane. (g) Adsorption kinetics of SSP membrane and SSPP membrane for uranium in natural seawater. (h) Adsorption selectivity of SSPP membrane in natural seawater.