Removal and regeneration of As(V) in aqueous solutions by adsorption on calcined fluorapatite

Herein, Fluorapatite has been calcined and successfully applied for the removal of As(VI). The materials prepared have been characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermogravimetric analysis and point zero charge pH were also considered as part of these characterizations. Several parameters affecting the adsorption process were studied in this work, such as the mass, time, pH, and the initial concentration effect. The experimental data were modeled using kinetics (pseudo-first-order, PS1 and pseudo-second-order, PS2) and isotherm (Langmuir and Freundlich) models to understand the mechanism related to the uptake process. As(V) uptake was relatively rapid and was highly dependent on pH. The pseudo-second-order rate expression supported data best, while the Langmuir equation could satisfactorily describe isotherm data. Finally, Fluorapatite calcined has been successfully reused for more than 5 cycles without significant loss of its sorption capacity.