Preparation and application of magnesium oxide nanoparticles for superiorly fluoride removal

An environmentally friendly and simple homogeneous precipitation method synthesized MgO nanoparticles with highly efficient fluorine removal. The prepared MgO nanoparticles have an average size of 53 nm, the composition and structure of MgO nanoparticles were analyzed by XRD, SEM, TEM, STEM and BET. The high specific surface area (242.6 m2/g) and abundant pores (1.18 cm3/g) of MgO nanoparticles contribute to the increase of adsorption sites. The adsorption properties of MgO nanoparticles for fluorine were investigated by discussing the adsorption kinetics, isotherms and thermodynamics, the outcomes demonstrated that the Pseudo-second-order kinetics, Langmuir isotherm model and Freundlich model could describe the adsorption behavior for fluorine, and the maximum adsorption capacity is 372.65 mg/g. The Gibbs free energy change G°< 0 at different temperatures proves that the adsorption for fluorine by MgO is endothermic and spontaneous. In addition, the findings from FT-IR, XRD, XPS and hydrochemical equilibrium analysis demonstrate that the substances that play an adsorption role in MgO nanoparticles, and analyzed the reason why MgO nanoparticles have better adsorption properties than commercial MgO. Moreover, the environmental factors such as pH (3−10) and coexisting ions (Cl-, NO32-, SO42-, HCO3-, CO32-, PO43-) that may affect adsorption property in practical applications are also explored. The separation percentage of the adsorbent from the aqueous solution after adsorption indicates that it can be easily separated from water by filtration. Hence, the MgO nanoparticles in this study can be considered as a fluorine adsorbent with great potential.