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چکیده
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The new nanocomposite of NaP-Hydroxyapatite (NaP:HAp) has been developed for removalof fluoride from aqueous solution. NaP:HAp nanocomposite has been characterized by usingdifferent method such as: X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR), scanning electron microscope (SEM), Energy Dispersive X-ray analysis (EDAX), sur-face area (BET) and thermal gravimetric analysis (TGA). Box–Behnken design with three-leveland four-factor has been employed for determination of effective process parameters suchas solution pH (4–11), temperature (25–55◦C), initial adsorbent dose (1–3 g) and initial fluo-ride concentration (5–25 mg/L) on removal of fluoride from aqueous solution. After 29 batchruns, Quadratic model was established by regression analysis of the experimental dataobtained from 29 batch runs. Quantity uptake of fluoride was evaluated using the Lang-muir, Freundlich and Dubinin–Radushkevich (DR) models. The rate of adsorption was rapidand followed pseudo-second-order kinetics for this adsorbent. Moreover, thermodynamicparameters (H◦, G◦, S◦) for fluoride sorption on NaP:HAp nanocomposite was also stud-ied from the temperature dependence. The significant novelty of this work is the simplepreparation of a new nanocomposite from Hydroxyapatite and zeolite that increased stabil-ity of HAp in different pH and temperature. Also, this nanocomposite shows high capacityfor adsorption of fluoride related of other sorbent and reusable for several times that makesthis method nearly green and friendly environmentally.
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