Oxygen Permeance

At each cyclohexane vapour pressure level, the oxygen permeance through the open pores of the membrane was measured. 

The measurements were performed at 20°C and the oxygen concentration was determined with a gas chromatograph. From the oxygen permeance data as a function of cyclohexane partial pressure the pore-size distribution was calculated with the Kelvin equation [25],... 

Oxygen Permeance (P 02) may be defined as the ratio of the oxygen transmission rate to the differential partial pressure of oxygen on the two sides of the film. Oxygen Permeabihty Coefficient (PO2) is the product of the permeance and the thickness of the him as shown by Eqn (8.19). 

Water transmission rate, g.m day 23"C, 85% r.h Figure 6 oxygen permeance vs water transmission rate of the main petroleum and biobased polymers (including steel, aluminum and glass)... 

Before and after experiments the pore sizes of the membranes were measured by permpo-rometry [16], a technique based on blocking of smaller pores by capillary condensation of cyclohexane and the simultaneous measurement of the permeance of oxygen gas through the larger, open pores. The measurements are performed at 20°C on an area of 8.5 10 4 m2. The pore size distribution (Kelvin radii) is determined in the desorption stage using the Kelvin equation. More details on the permporometry technique can be found in [17] and all experimental details of the permporometry apparatus are presented in [16],... 

Subsequent studies of these proton-transport membranes will be conducted over a wide range of hydrogen partial pressures on the permeate side. This will allow assessment of whether the driving force for hydrogen permeance is more accurately represented as the natural logarithm of the ratio of the hydrogen partial pressures on the retentate and permeate sides, as observed in ion transport oxygen membranes. 

The use of thinner membranes of this t)q)e increases the permeance but to a lesser extent the thirmer the membrane. With a thickness around 0.3 mm (depending on the precise system) surface reactions which transfer oxygen from the gas phase to solid material completely become rate determining. This phenomenon limits the much higher permeances which are potentially based on the very high bulk permeation (see Chapters 6 and 8). 

M.F. Carolan, P.N. Dyer, J.M. LaBar Sr. and R.M. Thorogood, Process for restoring permeance of an oxygen-permeable ion transport membrane utilized to recover oxygen from oxygen-containing gaseous mixtures. US Patent 5,240,473,1993. 

Calculate the permeances, permeabilities, fluxes, and the concentrations of oxygen and nitrogen on the membrane surfaces. The film resistances may be neglected. 

In an air separation process using a perfect-mixing membrane separator, the feed air flow rate is rip = 1 x 10 cm- (STP)/s, with mole fraction oxygen yp = 0.21 and mole fraction nitrogen yp2 = 0.79. The membrane permeances for oxygen and nitrogen are, respectively, 1.5 x 10" and... 

F1927-98el Determination of Oxygen Gas Transmission Rate, Permeability and Permeance at Controlled Relative Flumidity... 

Assume that the GTR of oxygen through a 1-mil PE film, GTR = 3.5 x 10" g/h m, when the partial pressure difference through the film Ap is 30 mm Hg. Calculate the permeance and the permeability coefficient. 

A multilayer structure of undefined composition but containing an EVOH layer has been evaluated for its barrier characteristics to oxygen using an Oxtran continuous flow apparatus (area = 100 cm ) and air. The steady state rate, Rss= 2.0 cmyday. Calculate the permeance of the structure in cmysec m Pa. (Answer R = 1.1 x 10 cc/s m Pa)... 

---