Low temperature synthesis and thermodynamic stability of fluorpyromorphite Pb5(PO4)3F at 5-65°C

• Autorzy: Dziura A. , Kwaśniak-Kominek M. , Manecki M. , Bajda T.
• Języki publikacji: EN

Abstrakty

EN

Fluorpyromorphite Pb5(PO4)3F belongs to the pyromorphite group of minerals which are isostructural with apatites. Their structure allows for variety of substitutions in both cationic and anionie positions. The purpose of this study is low temperature synthesis, mineralogical and thermodynamic characterization of fluorpyromorphite (FPY) and determination of its solubility product based on the results obtained from the dissolution experiment. FPY was synthesized by dropwise mixing of solutions containing Pb(NO3)2, K2HPO4 and NaF at 25°C. The only product of synthesis is FPY within the detection limits of X-ray diffraction. Calculated unit cell parameters are a = 9.1 ATI A, c = 7.3216 A. Homogeneous character of the precipitate was confirmed further with the use of scanning electron microscopy. Dissolution experiments were conducted in triplicates, open to the air, at 5, 25, 45°C and 65-C and at pH = 2.0. An aliquot of about 250 mg of FPY was placed in 250 mL of 0.05 M KNO3 with the pH adjusted using 0.1 M HNO3. Periodically taken samples were analyzed for [Pb] using atomic absorption spectrometry AAS as well as for [PO4] and [F] using colorimetry. Calculations of solubility products were performed with the aid of computer program PHREEQC with modified MINTEQ thermodynamic database. The activities of ionic species were calculated from measured concentrations of elements (assuming stoichiometric dissolution) with application of extended Debye-Huckel equation.

Słowa kluczowe

EN

Fluorpyromomorphite; FPY; low temperature; synthesis; thermodynamic stability

• Wydawca: Wydawnictwa AGH
• Czasopismo: Geology, Geophysics and Environment
• Rocznik: 2012
• Tom: Vol. 38, no. 4
• Strony: 465

Twórcy

autor

Dziura A.

• AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection; al. Mickiewicza 30, 30-059 Krakow, Poland

autor

Kwaśniak-Kominek M.

• AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection; al. Mickiewicza 30, 30-059 Krakow, Poland

autor

Manecki M.

• AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection; al. Mickiewicza 30, 30-059 Krakow, Poland

autor

Bajda T.

• AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection; al. Mickiewicza 30, 30-059 Krakow, Poland