Issue 6, 2017, Issue in Progress

Spontaneous supersaturation of calcium citrate from simultaneous isothermal dissolution of sodium citrate and sparingly soluble calcium hydroxycarboxylates in water

Abstract

Strongly supersaturated homogeneous calcium citrate solutions are formed spontaneously when solid sodium citrate and solid calcium hydroxycarboxylates are dissolved simultaneously in water or when solid sodium citrate is dissolved in an already saturated aqueous solution of the calcium hydroxycarboxylate at ambient conditions. Maximal supersaturation of calcium citrate was found to decrease for an increasing value of the stability constant for calcium binding: L-lactate < D-gluconate < citrate, indicating citrate assisted dissolution through competitive complex formation as a thermodynamic factor controlling spontaneous supersaturation for up to a factor of more than twenty. Time elapsing prior to initiation of precipitation of calcium citrate was found to be shorter for a higher degree of supersaturation and lasted between hours and days. During subsequent precipitation equilibrium solubility of calcium citrate was approached with a simultaneous increase in water activity. Both thermodynamic and kinetic factors are suggested to be important for the spontaneous supersaturation, which seems to explain the paradoxal but well-stablished high bioavailability of calcium from the sparingly soluble calcium citrate and the high mobility of calcium in the presence of citrate during biomineralization.

Graphical abstract: Spontaneous supersaturation of calcium citrate from simultaneous isothermal dissolution of sodium citrate and sparingly soluble calcium hydroxycarboxylates in water

Article information

Article type
Paper
Submitted
25 Oct 2016
Accepted
22 Dec 2016
First published
13 Jan 2017
This article is Open Access
Creative Commons BY license

RSC Adv., 2017,7, 3078-3088

Spontaneous supersaturation of calcium citrate from simultaneous isothermal dissolution of sodium citrate and sparingly soluble calcium hydroxycarboxylates in water

M. Vavrusova, A. C. Garcia, B. P. Danielsen and L. H. Skibsted, RSC Adv., 2017, 7, 3078 DOI: 10.1039/C6RA25807G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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