Synthesis of pillar and microsphere-like magnesium oxide particles and their fluoride adsorption performance in aqueous solutions

We synthesized pillar and microsphere-like MgO particles and their fluoride removal performance. Samples of MgO were synthesized by calcination of precursors derived from MgCO3 center dot 3H(2)O and characterized using field emission scanning electron microscopy, X-ray diffraction, and N-2 adsorption-desorption isotherms. The fluoride removal performance of the MgO samples was investigated in terms of adsorption kinetics and adsorption equilibrium. The effects of pH and the presence of other anions on the fluoride adsorption were also considered. The adsorption capacities of pillar and microsphere-like MgO particles were 151.51 and 166.66 mg/g, respectively. The pH of the aqueous solutions did not significantly affect the fluoride adsorption at pH 9 or lower. Except for phosphate, the effect of co-existing anions on fluoride adsorption was not considerable. Fluoride removal occurred through the substitution of hydroxyl groups on the surface of MgO with fluorides.