The crystallization of hydroxyapatite and fluorapatite in the presence of magnesium ions

Amjad, Zahid; Koutsoukos, Petros G.; Nancollas, G.H.

doi:10.1016/0021-9797(84)90025-0

Cited by 100 publications

(53 citation statements)

References 32 publications

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“…This ratio is defined as the affinity constant 25 and may be calculated from the slope of the linear fit of the kinetics data according to eq 10. The value of the affinity constant, although it lacks physical meaning, may be considered as a measure for the affinity of the adsorbate for the adsorbent.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Citrate and Phosphocitrate On Struvite Spontaneous Precipitation

Kofina

Demadis

Koutsoukos

2007

Crystal Growth & Design

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ABSTRACT:The effect of citrate and phosphocitrate ions on the spontaneous precipitation of magnesium ammonium phosphate hexahydrate (MgNH 4 PO 4 · 6H 2 O, struvite) at pH 8.50 and 25°C was investigated at conditions of constant solution supersaturation. The supersaturated solutions were prepared in synthetic wastewater. The presence of citrate and phosphocitrate in the working solutions showed reduction of the initial rates of struvite precipitation when compared with solutions in their absence. The parabolic dependence of the rates of precipitation on the relative solution supersaturation suggested a surfacediffusion-controlled mechanism. Presence of citrate and phosphocitrate in the supersaturated solutions at concentration levels from 1 to 10 µM resulted in a drastic increase in induction times. The presence of citrate and phosphocitrate inhibited struvite precipitation up to 75-80%. The reduction of precipitation rates was related to additive concentration following an expression suggested by the kinetic Langmuir-type adsorption model. The affinity constant calculated for citrate (8.2 × 10 5 ) was considerably higher than the respective value for phosphocitrate (0.6 × 10 5 ). Finally, it should be noted that the morphology of the prismatic, elongated struvite crystals precipitated in the presence of citrate and in the presence of phosphocitrate showed differences only in size.

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Section: Resultsmentioning

confidence: 99%

The Effect of Citrate and Phosphocitrate On Struvite Spontaneous Precipitation

Kofina

Demadis

Koutsoukos

2007

Crystal Growth & Design

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“…The composition of the titrant solutions in the two burettes was CaCl 2 and NaCl in the first and in the second KH 2 PO 4 and KOH. The molar concentration ratio of the titrants corresponds to the stoichiometry of the precipitating HAP, Ca : P : OH = 5 : 3 : 1 (23). As a result, the HAP crystallization took place under conditions of constancy on the supersaturation and on the concentration of the reactants.…”

Section: Methodsmentioning

confidence: 99%

The Crystallization of Hydroxyapatite in the Presence of Lysine

Koutsopoulos

Dalas

2000

Journal of Colloid and Interface Science

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“…It is in agreement with literature data, for example in Refs. [7,[48][49][50][51] it is reported that magnesium affects the formation of HAP. The results obtained in this work suggest that this may also be the case for CA.…”

Section: Chemical Speciation Analysismentioning

confidence: 99%

Solid Phases Precipitating in Artificial Urine in the Absence and Presence of Bacteria Proteus mirabilis—A Contribution to the Understanding of Infectious Urinary Stone Formation

et al. 2018

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Magnesium ammonium phosphate hexahydrate, called struvite, is the dominant component of infectious urinary stones. In addition to struvite, infectious urinary stones include solid phases with poor crystallinity as well as amorphous matter. This article is devoted to the analysis of these solid phases, because they have not been characterized well until now. The solid phases tested were obtained from artificial urine in the absence and presence of Proteus mirabilis. The solid phases were characterized by different techniques (X-ray Diffraction, Energy Dispersive X-ray, Scanning Electron Microscopy, as well as Raman and Infrared Spectroscopies). According to the results these phases are carbonate apatite (CA), hydroxylapatite (HAP), amorphous calcium carbonate (ACC), amorphous calcium phosphate (ACP) and/or amorphous carbonated calcium phosphate (ACCP). Carbonate apatite and hydroxylapatite may occur in non-stoichiometric forms, i.e., various anions can be substituted for CO 3 2− , OH − , and PO 4 3− groups in them. The non-stoichiometry of carbonate apatite and hydroxylapatite also implies a deficiency of calcium ions, i.e., calcium ions may be partially replaced by other cations. Experimental techniques and chemical speciation analysis demonstrate that the presence of magnesium influences the formation of CA and HAP.

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The crystallization of hydroxyapatite and fluorapatite in the presence of magnesium ions

Cited by 100 publications

References 32 publications

The Effect of Citrate and Phosphocitrate On Struvite Spontaneous Precipitation

The Effect of Citrate and Phosphocitrate On Struvite Spontaneous Precipitation

The Crystallization of Hydroxyapatite in the Presence of Lysine

Solid Phases Precipitating in Artificial Urine in the Absence and Presence of Bacteria Proteus mirabilis—A Contribution to the Understanding of Infectious Urinary Stone Formation

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