Performance and Mechanism of Calcium Peroxide for Fluoride Removal and Site Energy Distribution

• • CaO2 exhibits a maximum adsorption capacity of 479.8 mg·g−1 (Sips model), surpassing many conventional adsorbents, enabling high-efficiency fluoride removal even at low adsorbent dosages. • • The material's total pore volume of 0.51 cm3·g−1 and mesoporous structure facilitate rapid intraparticle diffusion, which is the rate-limiting step, ensuring fast adsorption kinetics. • • Surface site energies follow a normal distribution with an average of 13.36 kJ·mol−1, indicating heterogeneous adsorption sites that enhance binding affinity across a range of fluoride concentrations. • • The removal mechanism involves surface precipitation, ligand exchange, and electrostatic attraction, providing multiple pathways for fluoride immobilization and ensuring robust performance under varying water chemistry conditions.