Engineering Radiation-Tolerant Magnetic Bimetallic Spinel Interfaces for Selective U(VI)/Am(III) Sequestration via Hydroxyl-Mediated Actinide Coordination

The development of radiation-resistance adsorbents capable of stabilizing actinides metal ions under extreme radioactive condition and complex chemical environments remains a serious challenge in radioactive wastewater treatment. In this present study, magnetic CuFe2O4 nanostructures materials were engineered as a robust actinide-binding promising platform through a co-precipitation method, enabling efficient adsorb of chemically distinct U(VI) and Am(III) metal ions. The synthesized CuFe2O4 nanostructures materials showed excellent adsorption performance, showing maximum Langmuir capacities of 122 and 310 mg g−1 for U(VI) and Am(III), respectively. Adsorption kinetics and equilibrium experiments showed pseudo-second-order behavior and Langmuir-type monolayer adsorption, demonstrating the involvement of energetically favored surface coordination sites. Multiscale mechanistic studies using PXRD, FTIR, XPS, pH-dependent adsorption behavior, and surface charge analysis support the involvement of hydroxyl-mediated inner-sphere surface complexation in selective actinide adsorption onto the CuFe2O4 nanosurface. The hydroxyl-rich spinel interface offers abundant oxygen donor coordination sites, helping strong metal−oxygen interactions with uranyl and hydrated trivalent actinide species. Thermodynamic studies showed endothermic and spontaneous adsorption within the temperature range 298−328 K, with negative Gibbs free energy (ΔG° = −1.45 to −2.47 kJ mol−1 for U(VI) and −1.27 to −2.46 kJ mol−1 for Am(III)) metal ions, positive enthalpy changes (ΔH° = 8.75 and 10.60 kJ mol−1), and favorable entropy contributions (ΔS° = 34.20 and 39.80 J mol−1 K−1), demonstrating dehydration-assisted surface coordination along with structural rearrangement during actinide metal ion binding. Notably, CuFe2O4 materials maintained their surface oxygen functionality, crystal structure, and adsorption efficiency after γ-radiation exposure up to 300 kGy, retaining around 95% of their initial capacity. The intrinsic magnetic response facilitated facile adsorption, while regeneration studies revealed sustained performance over repeated five adsorption desorption cycles. This synergy of hydroxyl-mediated actinide metal ion coordination, magnetic recoverability, radiation resilience, and recyclability establishes CuFe2O4 nanomaterials as a robust promising platform for advanced environmentally friendly wastewater remediation.