In this work, an adsorbent was prepared based on the attachment of organophosphorus acid extractants, namely, D2EHPA, CYANEX 272, and CYANEX 301, to the surface of superparamagnetic magnetite (Fe3O4) nanoparticles. The synthesized nanoparticles were coated with oleic acid, first by a chemisorption mechanism and later by the respective extractant via physical adsorption. The obtained core–shell functionalized magnetite nanoparticle composites were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy, thermogravimetry, infrared absorption and vibrating sample magnetometry. All the prepared nanoparticles exhibited a high saturation magnetization capacity that varied between 72 and 46 emu g−1 and decreased as the magnetite nanoparticle was coated with oleic acid and functionalized. The scope of this study also included adsorption tests for lanthanum, cerium, praseodymium, and neodymium and the corresponding analysis of their results. Sorption tests ...

This work describes the development of a core–shell magnetic nanoadsorbent (Fe₃O₄@TiO₂) designed for the selective recovery of rare earth elements (REEs) from electronic waste. The synthesis involved the co-precipitation of magnetite coated with an anatase-phase TiO₂ layer, subsequently functionalized with organophosphorus groups using glycolic acid and phosphoric acid. This surface modification, verified via FT-IR spectroscopy and zeta potential analysis, provided the material with a high density of active sites. Adsorption studies with lanthanum revealed that the process follows pseudo-second-order kinetics, reaching equilibrium in only 15 min with a theoretical model-calculated capacity of 19.4 ± 0.8 mg/g at pH 5. The material demonstrated high stability and reusability, maintaining 75% of its adsorption capacity after five cycles with a corresponding H₂SO₄ desorption efficiency of 58–60%. Finally, the nanoadsorbent was validated on real LCD screen leachates following an upstream pH 5.0 pre-neutralization and filtration stage designed to remove massive baseline concentrations of iron and copper. Although residual copper and chromium acted as the primary competitors within the remaining complex matrix, the material effectively partitioned REEs (Gd, Y, Ce, Pr, Nd, and Sm) present at ultra-low trace levels (μg/L), demonstrating its potential for urban mining and the circular economy.