SYNTHESIS, PERFORMANCE, AND MECHANISM OF MAGNESIUM-IRON-ALUMINUM TRIMETAL COMPOSITE AS AN ADSORBENT FOR FLUORIDE REMOVAL IN WATER TREATMENT

In this study the Mg-Fe-Al trimetal composite was successfully synthesized by an easy co-precipitation method and used as the adsorbent for fluoride removal from aqueous solutions. Synthetic conditions such as Mg/Fe/Al molar ratio and calcination temperature were studied to optimize the adsorbent. The adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FTIR). Batch adsorption studies were conducted under various conditions, such as different fluoride concentration, contact time, temperature, initial solution pH, and coexisting anions. Results indicated that the adsorbent obtained the maximum adsorption capacity of 92.85 mg/g for fluoride with a Mg/Fe/Al molar ratio of 30:1:4, calcined at 500 degrees C, at near-neutral pH and room temperature (25 degrees C). The adsorption data were fitted well with the Langmuir isotherm model and the pseudo-first order kinetic model. The adsorption mechanism involved electrostatic interaction on the surface, ion exchange interaction, and reconstruction of original layered structure by rehydration of mixed metal oxides. All results indicated that the Mg-Fe-Al trimetal composite can be a very promising material, has potential application in the removal of fluoride in water treatment, and has positive effects on human health.