Optimization of fluoride removal from aqueous solution by Al[2]O[3] nanoparticles

Abstract

According to World Health Organization (WHO), fluoride has a narrow prescribed concentration level in drinking water (< 1.5 mg L− 1) and defluoridation of water is necessary to remove elevated concentrations of fluoride from water. In the present work, aluminium acetylacetonate was used as a precursor which was dissolved in methanol to produce Al2O3 nanoparticles by flame spray pyrolysis (FSP) technique. Al2O3 nanoparticles were characterized by various techniques (e.g. Brunauer-Emmet-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier Transform Infrared (FTIR) to get an insight of their physicochemical properties. The effects of different variable parameters such as solution pH (3 − 11), contact time (5–180 min), initial fluoride concentration (0–30 mg L− 1), temperature (25, 35 and 45 °C) and competing anions (chloride, nitrate, carbonate, sulfate and phosphate) were investigated to study the adsorption of fluoride from water. Among different kinetic and isotherm models studied, the pseudo-second-order model best described the kinetics, while equilibrium data were well fitted by the Langmuir isotherm model. The competing anions on defluoridation from water followed the order: phosphate > carbonate > sulfate > nitrate > chloride. Results from this study revealed the potential utility of Al2O3 nanoparticles for defluoridation of water.