Phase relations in the calcium carbonate/ammonium phosphate system under aqueous conditions and 25°C

Abstract

A theoretical and experimental approach was applied to investigate phase relations in a system containing calcium carbonate and different ammonium phosphate solutions. Using laboratory experiments and thermodynamic modeling, this paper provides an insight into the formation of stable phase assemblages in the calcium carbonate and mono‐, di‐, triammonium phosphate aqueous system. Focus is placed on the morphological and mineralogical characterization and thermodynamic calculation of calcium phosphates precipitating due to the reaction between the calcium carbonate and ammonium phosphate solutions. Correlations between the formed stable calcium phosphate phases and the ammonium phosphate precursors are provided. Advantages and limitations of various analytical and modeling techniques used in this study such as geochemical equilibrium‐based modeling, X‐ray diffraction, scanning electron microscopy, and thermal analysis, are critically evaluated. Additionally, possible impacts of the ammonium phosphate solution type on the kinetics of phase transformations are discussed.

Development of a thermodynamic approach to assist the control of the precipitation of hydroxyapatites and associated calcium phosphates in open systems

“…[33][34][35] From an industrial point of view, the establishment of such interconnection between the experimental parameters and the properties of the synthesized materials is of the utmost interest. [36][37][38] The purpose of this study lies in the indepth analysis of the thermodynamic aspects of the competitive precipitation of CaPs, whereas the complementary kinetic aspects will be investigated in a forthcoming article. Synthesized CaP powders have been characterized by X-Ray diffraction (XRD), Raman spectroscopy, X-Ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM) and N 2 sorption.…”

Synthesis of High‐Purity Monocalcium Phosphate Monohydrate from Crab Shell Waste

“…Following MCPM production, calcium orthophosphates can be precipitated from calcium carbonate and ammonium phosphate solutions, resulting in morphological and mineralogical changes [26][27][28], with MCPM frequently crystallizing as elongated platelets. Monocalcium phosphates, the related calcium salts, may exist in hydrated and anhydrous crystalline phases.…”