scholarly journals A Physical Interpretation of the Phenomenological Coefficients of Membrane Permeability

1961 ◽  
Vol 45 (1) ◽  
pp. 143-179 ◽  
Author(s):  
O. Kedem ◽  
A. Katchalsky
Keyword(s):  
Reflection Coefficient ◽  
Physical Interpretation ◽  
Electrical Current ◽  
Distribution Coefficients ◽  
Ion Concentration ◽  
Solute Permeability ◽  
Reference Curves ◽  
Phenomenological Coefficients ◽  
Charged Membranes ◽  
Solute Permeability Coefficient

A "translation" of the phenomenological permeability coefficients into friction and distribution coefficients amenable to physical interpretation is presented. Expressions are obtained for the solute permeability coefficient ω and the reflection coefficient σ for both non-electrolytic and electrolytic permeants. An analysis of the coefficients is given for loose membranes as well as for dense natural membranes where transport may go through capillaries or by solution in the lipoid parts of the membrane. Water diffusion and filtration and the relation between these and capillary pore radius of the membrane are discussed. For the permeation of ions through the charged membranes equations are developed for the case of zero electrical current in the membrane. The correlation of σ with ω and Lp for electrolytes resembles that for non-electrolytes. In this case ω and σ depend markedly on ion concentration and on the charge density of the membrane. The reflection coefficient may assume negative values indicating anomalous osmosis. An analysis of the phenomena of anomalous osmosis was carried out for the model of Teorell and Meyer and Sievers and the results agree with the experimental data of Loeb and of Grim and Sollner. A set of equations and reference curves are presented for the evaluation of ω and σ in the transport of polyvalent ions through charged membranes.

Differential action of plasma and albumin on transcapillary exchange of anionic solute

1993 ◽  
Vol 264 (5) ◽  
pp. H1428-H1437 ◽  
Author(s):  
V. H. Huxley ◽  
F. E. Curry ◽  
M. R. Powers ◽  
B. Thipakorn
Keyword(s):  
Reflection Coefficient ◽  
Permeability Coefficient ◽  
Protein Composition ◽  
Solvent Drag ◽  
Solute Permeability ◽  
Charge Selectivity ◽  
Microvessel Wall ◽  
Solute Permeability Coefficient ◽  
Differential Action ◽  
Alpha Lactalbumin

We tested two hypotheses to account for the reduction in coupling of anionic solute to water flow (solvent drag) in microvessels during perfusion with plasma compared with albumin. Solvent drag is determined by both hydraulic conductivity (Lp) and solute reflection coefficient (sigma). Accordingly, decreased solvent drag during plasma perfusion must be the result of an increase in sigma (hypothesis 1) or reduction of Lp (hypothesis 2) or some combination of both mechanisms. These hypotheses were assessed by measuring Lp, sigma, and diffusive solute permeability (Psd) to the anionic protein alpha-lactalbumin in frog mesenteric exchange microvessels during plasma or albumin perfusion. The solute permeability coefficient to alpha-lactalbumin (Ps alpha-lactalbumin) was lower during exposure to plasma than bovine serum albumin (BSA) [(Ps alpha-lactalbumin)plasma/(Ps alpha-lactalbumin)BSA = 0.31 +/- 0.11 (means +/- SE, n = 9)]. Solute reflection coefficient to alpha-lactalbumin (sigma alpha-lactalbumin) was 0.69 +/- 0.02 in plasma and 0.34 +/- 0.03 in BSA (n = 7). Lp was not significantly influenced by perfusate protein composition (Lp plasma/Lp BSA = 1.02 +/- 0.11; n = 20). These data lead to the conclusion that the actions of plasma are to confer charge selectivity for anionic solute and, to a lesser extent, modify the porous pathways of the microvessel wall. Taken together, these results indicate that porous pathways contribute significantly to macromolecular flux in plasma-perfused vessels.

scholarly journals Implementation of Spiegler–Kedem and Steric Hindrance Pore Models for Analyzing Nanofiltration Membrane Performance for Smart Water Production

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 78 ◽  
Author(s):  
Remya Nair ◽  
Evgenia Protasova ◽  
Skule Strand ◽  
Torleiv Bilstad
Keyword(s):  
Mass Transfer ◽  
Reflection Coefficient ◽  
Oil Recovery ◽  
Water Permeability ◽  
Structural Parameters ◽  
Pure Water ◽  
Model Parameters ◽  
Water Production ◽  
Solute Permeability ◽  
Smart Water

A predictive model correlating the parameters in the mass transfer-based model Spiegler–Kedem to the pure water permeability is presented in this research, which helps to select porous polyamide membranes for enhanced oil recovery (EOR) applications. Using the experimentally obtained values of flux and rejection, the reflection coefficient σ and solute permeability Ps have been estimated as the mass transfer-based model parameters for individual ions in seawater. The reflection coefficient and solute permeability determined were correlated with the pure water permeability of a membrane, which is related to the structural parameters of a membrane. The novelty of this research is the development of a model that consolidates the various complex mechanisms in the mass transfer of ions through the membrane to an empirical correlation for a given feed concentration and membrane type. These correlations were later used to predict ion rejections of any polyamide membrane with a known pure water permeability and flux with seawater as a feed that aids in the selection of suitable nanofiltration (NF) for smart water production.

scholarly journals Nonconservative current-induced forces: A physical interpretation

2011 ◽  
Vol 2 ◽  
pp. 727-733 ◽  
Author(s):  
Tchavdar N Todorov ◽  
Daniel Dundas ◽  
Anthony T Paxton ◽  
Andrew P Horsfield
Keyword(s):  
Physical Interpretation ◽  
Current Flow ◽  
Test Procedure ◽  
Electrical Current ◽  
Stimulated Emission ◽  
General Definition ◽  
Noninvasive Test ◽  
Electrical Current Flow ◽  
Definition Of ◽  
A Current

We give a physical interpretation of the recently demonstrated nonconservative nature of interatomic forces in current-carrying nanostructures. We start from the analytical expression for the curl of these forces, and evaluate it for a point defect in a current-carrying system. We obtain a general definition of the capacity of electrical current flow to exert a nonconservative force, and thus do net work around closed paths, by a formal noninvasive test procedure. Second, we show that the gain in atomic kinetic energy over time, generated by nonconservative current-induced forces, is equivalent to the uncompensated stimulated emission of directional phonons. This connection with electron–phonon interactions quantifies explicitly the intuitive notion that nonconservative forces work by angular momentum transfer.

The use of linear nonequilibrium thermodynamics in the study of renal physiology

1979 ◽  
Vol 236 (3) ◽  
pp. F211-F219
Author(s):  
A. Essig ◽  
S. R. Caplan
Keyword(s):  
Reflection Coefficient ◽  
Systematic Study ◽  
Nonequilibrium Thermodynamics ◽  
Flow System ◽  
Nonequilibrium Thermodynamic ◽  
Transport Processes ◽  
Renal Physiology ◽  
Onsager Reciprocity ◽  
Phenomenological Coefficients ◽  
Osmotic Pressure Difference

Classical formulations for the analysis of membrane transport processes, which ignored possible interactions between flows of diverse permeant species, often led to inconsistencies in the evaluation of permeability coefficients. For water flow induced by an osmotic pressure difference this difficulty was resolved by Staverman's introduction of the reflection coefficient sigma, a parameter which incorporates the interaction between solute and solvent in the course of their passage through a membrane. A comprehensive nonequilibrium thermodynamic (NET) formalism suitable for many biological systems was provided by Kedem and Katchalsky. For an n-flow system each flow is in general dependent on n forces; the assumption of Onsager reciprocity, however, reduces the number of independent phenomenological coefficients. Although NET is widely applied in the study of renal physiology, fundamental theoretical and practical problems remain. Basic considerations are the need to control or evaluate the influence of all coupled flows and to establish conditions fostering linear dependencies of flows on forces. When this is done a transport system may be characterized in terms of intrinsic membrane parameters, facilitating the systematic study of the effects of drugs, hormones, and various experimental perturbations.

Effect of oxide ions on separation factors of actinides from lanthanides in reductive extraction

2009 ◽  
Vol 97 (4-5) ◽  
Author(s):  
Hirotake Moriyama ◽  
K. Moritani ◽  
T. Toda ◽  
H. Hayashi
Keyword(s):  
Distribution Coefficients ◽  
Ion Concentration ◽  
Extraction System ◽  
Separation Factors ◽  
Oxide Ions ◽  
Oxide Ion ◽  
Metal Phases

AbstractThe distribution coefficients of Am, Ce, and Eu between the salt and metal phases were measured at 1073 K in a reductive extraction system of equimolar NaCl-KCl melt and liquid Ga. By changing the solute concentrations, it was observed that the distribution coefficients were dependent on the oxide ion concentration in the system, possibly due to the formation of such compounds as AmO

scholarly journals Hg (II) extraction in a PEG-based aqueous two-phase system in the presence of halide ions. I. Liquid phase analysis

2006 ◽  
Vol 4 (2) ◽  
Author(s):  
Laura Bulgariu ◽  
Dumitru Bulgariu
Keyword(s):  
Salt Solution ◽  
Distribution Coefficients ◽  
Ion Concentration ◽  
Phase System ◽  
Two Phase ◽  
Rich Phase ◽  
Halide Complexes ◽  
Observed Behaviour ◽  
Partition Behaviour ◽  
Solution Acidity

AbstractThe partition behaviour of Hg (II) was studied in an aqueous polyethylene glycol (PEG) — (NH4)2SO4 two-phase system as a function of halide, halide concentration, and pH. For a system prepared by mixing equal volumes of 40 % (w/w) PEG (1550) with 40 % (w/w) (NH4)2SO4, Hg(II) remains almost exclusively in the salt-rich phase. The addition of NaX (X = Cl−, Br−, I−) enhances Hg (II) partition into the PEG-rich phase due to the formation of halide complexes. The efficiency of halide extractants increases in the order: Cl− < Br− < I−. Mercury extraction is improved at lower halide ion concentration by higher stock salt solution acidity. From the distribution coefficients determined as a function of halide ion concentration, the extracted species were identified. The Hg (II) extractability is determined by the type and stability of the Hg (II) halide species, and depends on the stock salt solution acidity. The observed behaviour is discussed and a possible extraction mechanism is proposed.

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