 |
| Titel |
Synthesis and solubility of Pb-Ca and P-As hydroxylapatite solid solutions |
| VerfasserIn |
Bartosz Puzio, Maria Młynarska, Joanna Motyka, Joanna Oknińska, Agnieszka Mandelt, Patrycja Chlebowska, Monika Kwaśniak-Kominek, Maciej Manecki |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128425
|
| Publikation (Nr.) |
 EGU/EGU2016-8413.pdf |
|
|
|
|
|
| Zusammenfassung |
| The objective of the study are three solid solution series:
- HPY hydroxylpyromorphite Pb5(PO4)3OH – HAP hydroxylapatite Ca5(PO4)3OH
- HAP hydroxylapatite Ca5(PO4)3OH – JBM johnbaumite Ca5(AsO4)3OH
- JBM johnbaumite Ca5(AsO4)3OH – HMI hydroxylmimetite Pb5(AsO4)3OH
The phases were synthesized from aqueous solutions at high pH (over 8) at ambient
temperature by dropwise mixing of chemical reagents: Pb(NO3)2, Ca(NO3)2.4H2O,
(NH4)H2PO4, and Na2AsHO4.7H2O. The products of all syntheses are crystalline,
monomineral fine powders (crystal size less than 1 μm). Their chemical composition is close
to theoretical. Systematic shift of XRD peaks and FTIR or Raman bands is observed within
the solid solution series.
Dissolution experiments were run at 5oC, 25oC, 45oC, and 65oC. An aliquot
of 0.5g of each phase was dissolved in 250 mL of 0.05M NH4NO3 (pH between
3 and 5) for about 3 months. In all cases dissolution resulted in increase of pH
by about 1. The systems were considered in equilibrium when three consecutive
samplings (ca. two weeks apart) resulted in similar concentrations (within 3 standard
deviations).
The dissolution of all phases in question is incongruent. The amount of precipitating
secondary phases was too small for identification. The results of HPY – HAP dissolution
experiments are inconclusive due to strongly incongruent dissolution. This is partially in
contrary to recent report by Zhu et al. (2015). Systematic increase of solubility is observed in
HAP – JBM series. Also, the solubility of these phases increases with the increase of
temperature. This is more pronounced for HAP than for JBM. Systematic increase of
solubility is also observed in HMI – JBM series.
This work is partially funded by AGH research grant no 11.11.140.319 and partially by
Polish NCN grant No 2014/01/M/ST10/00355.
Zhu,Y., Zhu, Z., Zhao, X., Liang, Y., Huang, Y., 2015. Characterization, dissolution, and
solubility of lead hydroxypyromorphite Pb5(PO4)3OH at 25–45oC. Journal of Chemistry,
vol. 2015, article ID 269387 |
|
|
|
|
|
|