A novel Fe-Al-La trioxide composite: Synthesis, characterization, and application for fluoride ions removal from the water supply

A novel Fe-Al-La composite adsorbent was synthesized via the co-precipitation method for water defluorination. The adsorbent was characterized by XRD, BET, SEM/EDS, and FT-IR. Its adsorption behavior was thoroughly carried out to investigate the fluoride removal performance in synthetic and real groundwater samples. The Langmuir model was found to describe the adsorption isotherm, presenting a maximum adsorption capacity of 28.06 mg g−1 at 298 K and pH = 8.25. The adsorbent material's fluoride removal performance can be associated with the synergistic effect of some properties such as amorphous structure, porosity, and Fe-Al-La interactions in the surface material. The linear driving force model was successfully used for describing the adsorption capacity with a surface diffusion ranging from 3.52 to 5.928 × 10–9 cm2 s−1. Results showed that the new composite might be applied to remove fluoride from water aiming at human consumption, achieving the established permissible limit for Water Health Organization (< 1.5 mg L−1).