LAPSE:2020.1284
Published Article
LAPSE:2020.1284
Synthesis of Calcium Orthophosphates by Chemical Precipitation in Aqueous Solutions: The Effect of the Acidity, Ca/P Molar Ratio, and Temperature on the Phase Composition and Solubility of Precipitates
Mykola V. Nikolenko, Kateryna V. Vasylenko, Victoria D. Myrhorodska, Andrii Kostyniuk, Blaž Likozar
December 28, 2020
Studies on chemical precipitation of the calcium orthophosphates have shown that their phase compositions do not vary depending on molar ratio Ca/P but are sensitive to solutions acidity and temperature. These are two key factors that determine the phase transformation progress of metastable phases into less soluble precipitates of the phosphates. It was proposed to compare calcium orthophosphates solubility products with calcium cations quantities in their formulas. It was found that there was a linear correlation between calcium orthophosphates specific solubility products and their molar ratios Ca/P if hydroxyapatite and its Ca-deficient forms were excluded from consideration. It was concluded that the relatively large deviations of their solubility products from the found correlation should be thought of as erroneous data. That is why solubility products were changed in accordance with correlation dependence: pKS for hydroxyapatite was 155, pKS for Ca-deficient hydroxyapatites was 114−155. The solubility isotherms, which were calculated on the basis of the corrected pKS values, coincided with the experimental data on solid-phase titration by Pan and Darvell.
Keywords
Ca-deficient hydroxyapatite, hydroxyapatite, solubility isotherm, solubility product, wet chemical precipitation
Suggested Citation
Nikolenko MV, Vasylenko KV, Myrhorodska VD, Kostyniuk A, Likozar B. Synthesis of Calcium Orthophosphates by Chemical Precipitation in Aqueous Solutions: The Effect of the Acidity, Ca/P Molar Ratio, and Temperature on the Phase Composition and Solubility of Precipitates. (2020). LAPSE:2020.1284
Author Affiliations
Nikolenko MV: Faculty of Chemical Technologies and Ecology, Ukrainian State University of Chemical Technology, Gagarin Avenue 8, 49005 Dnipro, Ukraine [ORCID]
Vasylenko KV: Faculty of Chemical Technologies and Ecology, Ukrainian State University of Chemical Technology, Gagarin Avenue 8, 49005 Dnipro, Ukraine
Myrhorodska VD: Faculty of Chemical Technologies and Ecology, Ukrainian State University of Chemical Technology, Gagarin Avenue 8, 49005 Dnipro, Ukraine
Kostyniuk A: Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia [ORCID]
Likozar B: Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia; Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1001 Ljubljana, Slovenia [ORCID]
Journal Name
Processes
Volume
8
Issue
9
Article Number
E1009
Year
2020
Publication Date
2020-08-19
Published Version
ISSN
2227-9717
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Original Submission
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PII: pr8091009, Publication Type: Journal Article
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LAPSE:2020.1284
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doi:10.3390/pr8091009
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Dec 28, 2020
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Dec 28, 2020
 
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Calvin Tsay
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