Osmotic Permeability

By order of magnitude the diffusion permeability of commercial membranes 

Hydraulic permeability is measured as the volume of liquid passed through one unit of a membrane surface for one time unit at one unit of pressure difference. For most commercial membranes this parameter has a value of 10 ° -10 cm g s  

Water can penetrate through either gel areas or intergel areas in a homogenous membrane. The intergel areas are less crosslinked, and the water flow would meet less resistance in these areas. However, the volumetric fraction of intergel areas is small therefore, it is not possible to predict the contribution of gel areas and intergel areas in the total hydraulic permeability. 

The nature of the membrane matrix has significant influence on water mobility in the membrane. Water diffusion coefficients are high in perfluorinated membranes with weak hydrophiUc interaction [2]. The coefficients are lower for membranes with hydrocarbon matrix with stronger hydrophihc interaction. A correlation exists between the self-diffusion coefficients of water and co-ions the water 

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Table I. Parameters of the Osmotic Permeability of Water across the Oil Layer in a Series of Water/Liquid-paraffin/Water Emulsions prepared by 30 Span 80 in the Oil Phase and 1% Tween 80 in the Suspending Fluid. "Reproduced with permission from Ref. 16. Copyright 1900, Academic Press. "...

In this equation, n is the porosity and A is the cross-sectional area of the soil. Furthermore, it should be noted that the use of the effective porosity (n ) or the porosity (n) divided by the tortuosity squared (n/r) may be more accurate than using the porosity (n). For civil engineering apphcations, the electro-osmotic permeability coefficient (k ) is computed as follows ... 

Vane LM, Zang GM. (1997). Effect of aqueous phase properties on clay particle zeta potential and electro-osmotic permeability Implications for electro-kinetic soil remediation processes. Journal of Hazardous Materials 55 1-22. 

In many cases, the difference between Pf and P can be attributed to the presence of an unstirred layer. On the other hand, in the case of human red cell membrane the difference cannot be accounted for by the presence of an unstirred layer [14]. Additional support for this difference between Pf and Pdealing with the effect of antidiuretic hormone (ADH) on water movement across epithelia. It was found that in the presence of ADH, the osmotic permeability coefficient of this tissue to water is 120 times greater than the diffusional coefficient (see Table 9.5 in [23]). 

Experimental set-up used for the measurement of hydrodynamic permeability, thermo-osmotic permeability and thermo-osmotic pressure difference is shown in Eig. 3.3. The membrane was fixed with araldite between two ground-glass joints. Thermocouples were inserted through the adjoining tubes so that the junctions touched the membrane. 

Thermo-osmotic permeability and simple permeability were measured for water and methyl alcohol. Toluene and ethanol were also tried, but even simple permeation was not detectable for ethanol. Permeation occurred with ethanol only when the membrane was treated with zinc chloride solution. 

Figure 3.6. Estimation of thermo-osmotic permeability of water and methanol.

The thermo-osmotic permeability and the ordinary permeability of water is greater than that for methanol. For these reasons, thermo-osmosis of water could not be detected... 

Studies on hydrodynamic permeability, thermo-osmotic permeability for DjO have also been carried out and heat of transport has been estimated. Similar measurements have been made for solutions of KCl in H2O and DjO using a copper ferrocyamide membrane. These results support the theory of non-equilibrium thermodynamics within a limited range of departure from equilibrium [28]. 

E, electric field K, hydraulic coefficient IT, osmotic pressure head (11 = efficient h, hydraulic head k-p, thermo-osmotic permeability (m /(K s)). n/pg) 7], coefficient of osmotic efficiency s, Soiet co- ... 

Although morphologically most cellular membranes look alike, great differences are found in the osmotic permeability of cells. These differences probably result from differences in cell size and the existence of water-filled pores in the membrane. The permeability of the cell to water is not only a function of the membrane and the difference between osmotic pressures inside and outside the cell, but it is restricted by the rate of diffusion inside the cell cytoplasm. 

Lit is called the osmotic permeability or solute permeability and is often referred to as co. 

Electro-osmotic permeability kg Permitivitiy s Zeta potential ... 

Aksimentiev, A. and Schulten, K., 2005. Imaging a-hemolysin with molecular dynamics Ionic conductance, osmotic permeability, and the electrostatic potential map, Biophys. /., 88, 3745-3761. 

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