Stabilitätskonstanten mononuclearer Phosphatokomplexe des Strontiums

Gnepf, H.; Gübeli, O.; Schwarzenbach, G.

doi:10.1002/hlca.19620450415

Cited by 5 publications

(2 citation statements)

References 7 publications

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“…The analytical collcentrations of the acidic buffer components (Ca2+ or S? ', phosphate, TEA, pH) and the stability constants of the species formed in solution' (26)(27)(28) allow the concentration of free CaIt or Sr" to be calculated (29). The major Ca" or Sr" species at pH 2.3 was M'kHP04'-and the free metal ion concentration was typically 3 x M for the total concentrations of metal ion typical of those encountered in the course of an experiment (1 to 2 x lo-' M).…”

Section: Transport Selectivitiesmentioning

confidence: 99%

Membrane transport systems. V. Coupled countertransport of alkaline earth cations and protons

Dulyea¹,

Fyles²,

Whitfield³

1984

Can. J. Chem.

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LYNN M. DULYEA, THOMAS M. FYLES, and DENNIS M. WHITFIELD. Can. J. Chem. 62, 498 (1984). The extraction and transport of alkaline earth cations from a basic to an acidic solution across an artificial membrane by crown ether carboxylic acids are reported. Monocarboxylate carriers achieve the transport via 2: 1 complexes or by ternary complexes in the presence of readily extractible anions, while dicarboxylate carriers transport cations as I : I complexes. Both types of carrier exhibit two regimes of kinetic behaviour depending on the relative concentrations of the carrier and the metal ion: a zero order regime in which the rate depends only on the carrier concentration, and a reversible consecutive first order regime in which the rate depends only on the metal ion concentration. In the former, the rate of adsorption of the carrier on the interface is presumed to be rate limiting while in the latter, the diffusion of metal ion to the interface is rate limiting. Carrier structure exerts a general influence over both the rate and selectivity of transport but this influence varies with the kinetic regime considered.LYNN M. DULYEA, THOMAS M. FYLES et DENNIS M: WHITFIELD. Can. J . Chem. 62, 498 (1984). On rapporte des extractions et des transports de cations d'alcalino-terreux de solutions basiques vers des solutions acides a travers une membrane artificielle effectuts par des Cthers couronnes d'acides carboxyliques. Les transporteurs monocarboxylCs permettent d'effectuer les transferts via des complexes 2: 1 ou par le biais de complexes ternaires en presence d'anions qui peuvent &tre extraits facilement; par ailleurs, les transporteurs dicarboxylts effectuent le transport des cations sous forme de complexes I : I . Les deux types de transporteurs presentent deux rtgimes de comportement cinCtique diffkrents suivant les concentrations relatives de transporteur et d'ion mCtallique: un rCgimc d'ordre zCro dans lequel la vitesse dtpend uniquement de la concentration de transporteur et un regime du premier ordre constcutif et rCversible dans lequel la vitesse dCpend uniquement de la concentration de l'ion mttallique. Dans le premier rCgime, on suppose que la vitesse d'adsorption du transporteur a I'interfacc est I'Ctape dkterminante alors que dans le dernier regime, la diffusion de l'ion mCtallique a I'interface serait I'ttape dtterminante. La structure du transporteur exerce une influence gCntrale i la fois sur la vitesse et sur la sClectivit6 du transport mais cette influence varie avec le regime cinCtique considtrC.[Traduit par le journal]

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Section: Transport Selectivitiesmentioning

confidence: 99%

Membrane transport systems. V. Coupled countertransport of alkaline earth cations and protons

Dulyea¹,

Fyles²,

Whitfield³

1984

Can. J. Chem.

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“…This would also explain the increase in &++ at low concentrations by the fact that the strontium is ousted from its relative immobile association with chondroitin to form a more mobile association with HP04--. 31 We can thus see that although the electrostatic model still gives a semiquantitative description of the behavior of the Sr++ diffusion coefficient in the presence of phosphate ions, as the theory now stands, this model does not specifically take into consideration phenomena such as the competition…”

Section: Adding Dibasic Sodium Phosphatementioning

confidence: 97%

Study of the self‐diffusion coefficients of cations in the presence of an acidic polysaccharide

Magdelénat¹,

Turq²,

Chemla³

1974

Biopolymers

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SynopsisSelf-diffusion coefficient measurements have been applied to the study of Na+, Ca++, and Sr++ in the presence of a linear acidic polysaccharide extracted from cartilage, i.e., chondroitin sulfate. A series of experimental determinations was made with and wit.hout supporting electrolytes, and an analysis of experiments involving the separat,ion of the electrostatic interaction terms by an extension of Manning's theory produced results showing the preponderant nature of these electrostatic terms. The specificity of each type of ion or the influence of the pH can be considered merely as higher order corrections with respect to the preceding interact,ions. Counterion concent,rat.iori ranges and pH ranges were determined, where either the alkaline-eart,h counterions become free and hence move with their normal diffusion rate, or these cations are associated with the polyelectrolyte molecule, thus giving a diffusion coefficient. similar to that of the macromolecule, or the apparent diffusion coefficient,s vary between these two ext.reme diffusion rates as a function of the association equilibria. This variation can be expressed as a function of the linear charge density parameter related to the structure of the polyelectrolyte, the value of which was determined and found in good agreement, with published values.

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Bibliography

Smith

Martell

1976

Critical Stability Constants

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Stabilitätskonstanten mononuclearer Phosphatokomplexe des Strontiums

Cited by 5 publications

References 7 publications

Membrane transport systems. V. Coupled countertransport of alkaline earth cations and protons

Membrane transport systems. V. Coupled countertransport of alkaline earth cations and protons

Study of the self‐diffusion coefficients of cations in the presence of an acidic polysaccharide

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