Removal of Fluoride from Drinking Water Using Novel Adsorbent Magnesia-Hydroxyapatite

In many parts of the world, fluoride in drinking water is responsible for notable public health issues. The present study is aimed to prepare a new adsorbent magnesia-hydroxyapatite (Mg-HAP) that can serve as a valuable defluoridating agent. Characterization of the synthesized adsorbent was done by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission electron microscope (TEM), and Scanning electron microscope (SEM)/Energy-dispersive X-ray spectroscopy (EDX) analysis to reveal the bonding patterns, phase characteristics, and microstructural and morphological details. The influences of pH, adsorbent dose, contact time, and initial fluoride concentration and the effect of interfering anions were studied. The defluoridation capacity was evaluated to be 1.4 mg/g, and the adsorbent showed very good capability to remove fluoride from contaminated water over a wide range of pH. Equilibrium modeling was done, and the experimental data was fitted into Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms. Study of the kinetic data for the adsorption process revealed that it follows pseudo-second-order reaction. It also indicated that the intraparticle diffusion contributes to the rate-determining step in the process. The quality of treated water was analyzed for total dissolved solids (TDS), turbidity, residual calcium, residual phosphorus content, electrical conductivity, hardness, and total alkalinity. The results obtained were very promising and confirmed the prospects of usage of Mg-HAP in defluoridation of drinking water.