Search results for "Donnan potential"

showing 3 items of 3 documents

Donnan equilibrium of ionic drugs in pH-dependent fixed charge membranes: theoretical modeling.

2002

Abstract We have studied theoretically the partition equilibrium of a cationic drug between an electrolyte solution and a membrane with pH-dependent fixed charges using an extended Donnan formalism. The aqueous solution within the fixed charge membrane is assumed to be in equilibrium with an external aqueous solution containing six ionic species: the cationic drug (DH + ), the salt cations (Na + and Ca 2+ ), the salt anion (Cl − ), and the hydrogen and hydroxide ions. In addition to these mobile species, the membrane solution may also contain four fixed species attached to the membrane chains: strongly acid sulfonic groups (SO 3 − ), weakly acid carboxylic groups in dissociated (COO − ) a…

IonsDonnan potentialAqueous solutionStereochemistryChemistryInorganic chemistryMembranes ArtificialElectrolyteHydrogen-Ion ConcentrationModels TheoreticalPermeabilitySurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsBiomaterialsPartition coefficientHydrophobic effectsymbols.namesakeColloid and Surface ChemistryMembranePharmaceutical PreparationsPartition equilibriumsymbolsCalciumSaltsSemipermeable membraneJournal of colloid and interface science
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Donnan phenomena in membranes with charge due to ion adsorption. Effects of the interaction between adsorbed charged groups

1993

A physical model for the modified Donnan phenomenon associated with ion adsorption on localized membrane sites is presented. This model accounts for the dependence of the concentration of adsorbed ions on electrolyte concentration and pH as it is influenced by the electrostatic interaction between adsorbed ions. The equilibrium thermodynamic concepts employed are based on the Donnan formalism for the ion equilibria between membrane and solution, and the Bragg–Williams approximation for an adsorption isotherm that incorported interaction between adsorbed ions. Our results include the concentration of charged groups in the membrane, the pH of the membrane phase solution, and the Donnan potent…

General Physics and AstronomyElectrolyteElectric chargeIonQuantitative Biology::Subcellular ProcessesCouplingsymbols.namesakeAdsorptionPhysics::Plasma PhysicsPhase (matter)Donnan Theory ; Membranes ; Electric Charges ; Ions ; Adsorption ; Coupling ; Mathematical ModelsPhysics::Chemical PhysicsPhysical and Theoretical Chemistry:FÍSICA::Química física [UNESCO]IonsConductive polymerDonnan potentialMembranesMathematical ModelsChemistrymusculoskeletal neural and ocular physiologyUNESCO::FÍSICA::Química físicaCondensed Matter::Soft Condensed MatterMembraneChemical physicssymbolsPhysical chemistryDonnan TheoryElectric ChargesAdsorptionThe Journal of Chemical Physics
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Pore entrance effects on the electrical potential distribution in charged porous membranes and ion channels

2007

Abstract Models for the electrical potential distribution in the interfacial region between a fixed charge membrane and an electrolyte solution have traditionally employed the Donnan equilibrium formalism that assumes discontinuous changes in concentrations and electric potential. In the case of the charged capillary membrane model, we propose to check rigorously the validity of this approach by solving the linearized Poisson–Boltzmann equation for the diffuse electrical double layer at the membrane|solution interface. The comparison of the resulting axial distribution for the electric potential with the Donnan potential drop shows that the discontinuous approach is only valid for membrane …

Donnan potentialChemistryGeneral Chemical EngineeringDrop (liquid)Analytical chemistryElectrolyteMechanicsPoisson–Boltzmann equationAnalytical Chemistrysymbols.namesakeMembraneElectrochemistrysymbolsElectric potentialDebye lengthIon channelJournal of Electroanalytical Chemistry
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