Sorption of Uranium and Plutonium Species over Mn-Doped Fe ₃ O ₄ Nanoparticles Dispersed in KIT-6: A Thermodynamically Controlled Process

The sorption of UO22+ and PuO22+ ions over mesoporous magnetic nanoparticles (MNPs) has garnered quite a bit of importance lately. Apart from different sorption studies with higher concentrations of UO22+ and PuO22+ ions, limited studies are available for the sorption of both UO22+ and PuO22+ ions together at the ultratrace level. The effect of different thermodynamic and kinetic parameters owing to different structural attributions affecting sorption efficiency has always been the gray area. This present manuscript deals with the sorption of both UO22+ and PuO22+ ions over the MNPs, which were dispersed in a silica-based mesoporous material called KIT-6 (Korea Advanced Institute of Science and Technology). The sorption behavior in these materials was investigated in terms of different structural parameters using several characterization techniques like X-ray Photoelectron Spectroscopy (XPS), zeta potential, Mössbauer spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, Fourier Transform Infrared (FTIR) Spectroscopy, and High-Resolution Transmission Electron Microscopy (HRTEM). These provide deep insights for the different structural factors such as surface charge, surface hydroxyl groups, particle size, and magnetic properties governing their sorption mechanism and capabilities. These materials uniquely show very high Kd values for sorption of both UO22+ (8.34 × 103 mL/g) as well as PuO22+ ions (4.75 × 104 mL/g) under optimized conditions like pH, temperature, and analyte concentration. Isotherm modeling studies show highly comparable sorption capacity for UO22+ ions (66.31 mg/g) following Langmuir adsorption behavior. It was established that mainly the thermodynamic parameters govern the sorption efficacy and not the kinetic parameters. Selectivity for the materials toward UO22+ and PuO22+ ions individually was tested in the presence of different interfering ions.