Enhancing Magnesium Phosphate Cement Paste for Efficient Fluoride Adsorption

Abstract

In the present study, we explore the synthesis and characterization of novel composite materials derived from magnesium phosphate cement by incorporating varying quantities of aluminum, iron oxide, or alumina. These composites demonstrate promising properties related to water resistance and significant specific surface areas. Furthermore, our investigations reveal that aluminum, iron oxide, and phosphate constituents exhibit an affinity for fluoride retention. Consequently, we apply these synthesized materials for fluoride adsorption. Our results indicate a noteworthy adsorption capacity, ranging from 2.35 mg/g for cement synthesized with 0.25 g of aluminum to 4.84 mg/g for materials synthesized with 1.5 g of aluminum. The influence of incorporating alumina or iron oxide into these matrices is thoroughly examined. Additionally, we investigated the optimal conditions utilizing a range of analytical techniques, including scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS), the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analyses (TGA). To further elucidate this process, we perform equilibrium modeling and present experimental data in accordance with the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms.