Dual-active-site PDA@PW₁₂ microspheres for high-efficiency uranium extraction via synergistic complexation and reduction

In this study, polydopamine@phosphotungstic acid composite microspheres for efficient uranium adsorption were successfully prepared through the in situ copolymerization of dopamine and phosphotungstic acid. Characterization results showed that the incorporation of phosphotungstic acid inhibited the agglomeration of polydopamine and increased the specific surface area to 48.07 m²/g while simultaneously generating W⁵⁺ active species through electron transfer. The prepared material achieved a maximum uranium adsorption capacity of 720.1 mg/g at pH = 5 and 318 K, with the adsorption following the pseudo-second-order kinetic model and Langmuir isotherm model, indicating spontaneous monolayer chemisorption. Mechanistic investigations confirmed that uranium adsorption occurred through the synergistic effect of surface complexation with functional groups (–OH/–NH₂) and the reduction of U(VI) to U(IV) by W⁵⁺ species. The composite maintained 93.3% desorption efficiency after five adsorption–desorption cycles and exhibited excellent selectivity toward U(VI). Thus, this work provides a promising strategy for the development of high-performance uranium adsorbents.