Synthesis of highly selective magnetic Fe3O4@SiO2–HOPO nanoparticles for efficient lutetium removal from wastewater

To remove lutetium from wastewater, superparamagnetic Fe 3 O 4 @SiO 2 –HOPO nanoparticles were successfully synthesized, containing approximately 460 μmol·g −1 of 3,2-HOPO. The material demonstrated high stability in 0.1 mol·L −1 HNO 3 and retained 97 % of its adsorption capacity after five cycles. The nanoparticles showed strong selectivity for lutetium, with minimal interference from coexisting ions in different matrices. This selective adsorption was primarily due to monodentate or multidentate chelation of 3,2-HOPO on the particle surface with lutetium. Adsorption equilibrium was achieved within 15 min, with a maximum capacity of 29 mg·g −1 , highlighting its potential for large-scale wastewater treatment.