Efficient removal of U(VI) by self-assembly organic-embedded mesoporous silica spheres

Abstract In this research, an in-situ encapsulation strategy for constructing two organic-embedded mesoporous silica spheres (OMSS-1 and OMSS-2) is presented, which achieves efficient U(VI) extraction from solution. By confining L-aspartic acid or citric acid within mesochannels (2.52 nm) during self-assembly, the composites attain exceptional U(VI) affinity. The OMSS-1 and OMSS-2 exhibit high U(VI) adsorption capacities of 172.4 and 188.3 mg/g. The adsorption isothermal and kinetic models are carried out to study the adsorption of U(VI) on the composites. The adsorption processes of U(VI) on OMSS-1 and OMSS-2 are in accordance with Langmuir model and the pseudo-second-order model. Crucially, aspartate-embedded spheres (OMSS-1) demonstrate excellent selectivity in multicomponent systems containing 13 competing ions. The confinement-stabilized ligands enable outstanding regenerability, retaining >93 % capacity over 5 adsorption-desorption cycles with minimal leaching (<0.8 wt%/cycle). This work provides a reference for the design and synthesis of advanced adsorption materials by reconciling the traditionally conflicting objectives of high capacity, specificity, and stability in radionuclide management.