Ligand-induced electronic and geometric modulation of zirconium-based adsorbents for efficient decontamination of fluoride and arsenite

Zirconium-based materials exhibit strong affinity for F⁻ and As(III), but their practical application is hindered by hydrolysis susceptibility and limited adsorption capacity for As(III). In this study, we employed a ligand modification strategy, incorporating five organic ligands (acetylacetone, malonic acid, acetic acid, citric acid, and tartaric acid) to synthesize structurally stabilized zirconium-based adsorbents (PZA) via the sol-gel method. The adsorption performance and underlying mechanisms for F⁻ and As(III) removal were systematically investigated. Our results demonstrate that ligand modification significantly optimizes the physicochemical properties of the materials, enhancing adsorption performance. The citric acid-modified adsorbent achieved a F⁻ adsorption capacity of 79 mg/g, a 1.4-fold increase over unmodified materials, whereas the acetylacetone-modified adsorbent reached an As(III) adsorption capacity of 258 mg/g, surpassing most reported materials. Density functional theory calculations reveal that ligands improve adsorption through dual mechanisms of “geometrical configuration regulation” and “electronic effect”: (1) Ligand modification alters the electrostatic potential distribution on the material surface, expanding positive and negative charge regions by 29–42 % and 20–26 %, respectively, thereby strengthening electrostatic interactions with pollutants; (2) Frontier orbital analysis indicates that ligands reduce the HOMO-LUMO energy gap (ΔE decreased by 3.0–24.6 %), enhancing electron transfer capability; (3) Binding energy calculations confirm the spontaneity of the adsorption process. This study provides a novel strategy for the rational design of high-performance environmental functional materials through precise ligand engineering.