Removal of fluoride from aqueous media by magnesium oxide-coated nanoparticles

In the present study, magnesium oxide (MgO)-coated magnetite (Fe3O4) nanoparticles have been synthesized for analyzing the fluoride scavenging potential via modification of sol-gel method. The characterization of the nanoadsorbent was done by means of scanning electron microscopy, energy dispersive analysis of x-rays, and dynamic light scattering analyses. Batch adsorption experiments were carried out by varying the parameters adsorbent dose (0.75-3g/L), initial fluoride concentration (5.6-25mg/L), and pH (5.0-7.0). The maximum removal of fluoride was estimated as 98.6% for an initial fluoride concentration of 13.6mg/L at optimal conditions: pH 6.0, adsorbent dosage of 2g/L, and contact time of 120min. Results revealed that the adsorption was rapid and the fluoride affinity depends on the solution pH, adsorbent dosage, and contact time. The equilibrium was obtained in less than 180min. The adsorption kinetic data were fitted well to the pseudo-second-order kinetic model. The adsorption equilibrium data were best fitted to the Langmuir isotherm model. Based on the results observed, it was identified that the prepared adsorbent posses adequate adsorption potential to remove the fluoride ions from the aqueous solution.