Interfacial copper engineering in cobalt ferrite nanoadsorbents enables chemoselective sequestration of radioactive...

The selective sequestration of actinides from highly acidic nuclear waste remains a significant challenge because of their complex aqueous speciation, corrosive processing environments, and the stringent requirements for radiation stability and sorbent recyclability. Herein, a copper-engineered cobalt ferrite magnetic nanoadsorbent (Cu-CoFe₂O₄) was synthesized via a facile co-precipitation method and systematically evaluated for the selective removal of Pu(iv), Pu(vi), and Am(iii) from nitric acid media. The concentrations of the radionuclides before and after adsorption were quantified by radiometric analysis using α-spectrometry for plutonium isotopes and γ-spectrometry for americium, enabling reliable assessment of adsorption performance under simulated nuclear waste conditions. Copper incorporation into the cobalt ferrite spinel framework tailors the surface coordination environment and creates chemically active hydroxyl-rich nano-interfaces that promote strong inner-sphere interactions with actinide species. The engineered nanoadsorbent exhibits excellent affinity toward Pu(iv), Pu(vi), and Am(iii), following the selectivity sequence Pu(iv) > Pu(vi) > Am(iii), with distribution coefficients of 9500, 8400, and 7200 mL g^-1, respectively. Adsorption follows pseudo-second-order kinetics and is well described by the Langmuir isotherm, indicating an endothermic monolayer chemisorption process dominated by surface complexation. Mechanistic investigations based on PXRD, FTIR, XPS, and surface charge analysis reveal that the enhanced adsorption originates from cooperative coordination between surface hydroxyl groups and the engineered Cu-modified spinel interface. Furthermore, the magnetic nanoadsorbent demonstrates excellent γ-radiation resistance, rapid magnetic separation, and efficient regeneration with minimal loss of extraction efficiency over repeated adsorption-desorption cycles. Owing to its high selectivity, radiation tolerance, magnetic recoverability, and operational durability, Cu-CoFe₂O₄ represents a promising candidate for the treatment of low-level radioactive liquid waste and other acidic actinide-bearing streams. This study highlights interface engineering of magnetic spinel nanomaterials as an effective strategy for developing next-generation radiation-resistant adsorbents for sustainable nuclear waste management.