Facile Synthesis of Mesoporous La-Doped CuFe2O4 Nanoparticles as Magnetic Adsorbents for Phosphate Removal

Abstract

Herein, we aim to synthesize mesoporous La-doped copper ferrites (CuFe_2–xLa_xO₄, where x = 0.0, 0.05, 0.1, and 0.2) as recoverable phosphate adsorbents through a simple coprecipitation method. The impact of La-doping on the crystalline structure, phase composition, morphology, surface elemental composition, surface functional groups, specific surface area, total pore volume, and magnetic properties was thoroughly investigated. The results revealed that all La-doped CuFe₂O₄ samples exhibited enhanced maximum adsorption capacity and improved rate constants for phosphate adsorption at near-neutral pH. These improvements are attributed to the strong affinity of La for phosphate ions, coupled with an increase in specific surface area and pore volume due to La-doping. Adsorption isotherms and kinetics followed the Langmuir and pseudo-second-order models, respectively. However, the magnetic properties decreased with increasing La content. Among the samples, CuFe_1.9La_0.1O₄ emerged as the most promising phosphate adsorbent, demonstrating an impressive maximum adsorption capacity while retaining good magnetic properties, which enabled efficient magnetic separation and reuse over three cycles with over 80% adsorption efficiency. Although further research is required to optimize the material properties, these La-doped CuFe₂O₄ adsorbents demonstrate significant potential for treating phosphate in wastewater at near-neutral pH, with the added advantages of easy recovery and reusability.