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Precipitation and phase transformation of dicalcium phosphate dihydrate in electrolyte solutions of simulated body fluids: Thermodynamic modeling and kinetic studies
Author(s) -
Rabadjieva Diana,
Sezanova Kostadinka,
Gergulova Rumyana,
Titorenkova Rositsa,
Tepavitcharova Stefka
Publication year - 2020
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.36929
Subject(s) - octacalcium phosphate , simulated body fluid , dissolution , materials science , precipitation , phase (matter) , electrolyte , thermodynamics , chemical engineering , phosphate , saturation (graph theory) , kinetic energy , metastability , mineralogy , inorganic chemistry , calcium , chemistry , scanning electron microscope , metallurgy , organic chemistry , physics , mathematics , electrode , combinatorics , quantum mechanics , meteorology , engineering , composite material
The metastable and stable equilibria of a precipitation in the biomimetic system Simulated Body Fluid (SBF)–CaCl 2 –K 2 HPO 4 –KOH–H 2 O were modeled in the pH region 3–7 at a Ca/P molar ratio of 1 using a thermodynamic approach. Saturation indices (SI) of the solid phases were calculated and used to prognose the salt precipitation/dissolution processes. At рН < 4, the solutions are undersaturated (SI < 0) in respect of all solid phases; co‐precipitation of dicalcium phosphate dihydrate (DCPD) and hydroxyapatite (HA) occurs at рН 4 while at рН > 4 the stable phase is DCPD but the number of other co‐precipitated solid phases increases. This result is associated with the increase in HPO 4 2− , CaHPO 4 0 , and KНРО 4 − species in the studied solution. The phase transformations of five model DCPD‐based calcium phosphate precursors in three simulated body fluids differing in their composition, to more stable octacalcium phosphate and hydroxyapatite was thermodynamically prognosed and experimentally confirmed by kinetic studies, as well as by chemical, XRD, SEM, and IR methods.