Enhanced fluoride removal by nanosized lanthanum hydroxide loaded on magnetic resin

Fluoride contamination from industrial discharge poses severe threats to environmental and human health. This urges a requirement for development of adsorbents with higher efficiency and better selectivity. In this study, lanthanum (La) hydroxide was in-situ deposited onto a magnetic polyacrylic anionic resin (NDMP) to synthesize a novel nanocomposite adsorbent (La-NDMP). La-NDMP exhibited maximum fluoride adsorption capacity at pH 3.0, with negligible La leaching at higher pH levels. The adsorption process followed pseudo-first-order kinetics, and the equilibrium data were well described by the Langmuir isotherm model. Importantly, the incorporation of La enhanced fluoride selectivity by resisting interference from competing anions. The adsorption mechanism involves electrostatic interactions between quaternary ammonium groups on the magnetic resin and fluoride ions, as well as the formation of inner-sphere La-F complexes. Experiments using actual wastewater confirmed that La-NDMP exhibited facile solid-liquid separation, high adsorption efficiency, and stable performance, highlighting its potential for industrial applications.