Diffusivity of carbon dioxide

For the diffusion of carbon dioxide at atmospheric pressure and a temperature of 293 K, at what time will the concentration of solute I mm below the surface reach 1 per cent of the value at the surface 1 At that time, what will the mass transfer rate fkmol nrV"1 j be ... 

Diffusion coefficients can be estimated with the aid of the mathematical description of the diffusion of carbon dioxide from the paint film (Scheme II). Film thickness, saturation concentration and carbon dioxide equilibrium concentration are known. The emission curves of carbon dioxide calculated by the model have been fitted with the actual emission curves in Figure 7. In this case carbon dioxide is not formed chemically. 

Gutknecht, J. Bisson, M. A. Tosteson, F. C., Diffusion of carbon dioxide through lipid bilayer membranes. Effects of carbonic anhydrase, bicarbonate, and unstirred layers, J. Gen. Physiol. 69, 779-794 (1977). 

Many polymers are used in barrier applications, either to keep contents in or contaminants out. Food packaging is an excellent example of such usage. Plastic films and containers of many types are used to package food. Blow moldedbottles often contain numerous layers, each of which provides specific benefits. Polyethylene layers are excellent water barriers, polyvinyl alcohol is a good oxygen barrier, and polyethylene terephthalate impedes the diffusion of carbon dioxide from carbonated drinks. Other barrier applications include toothpaste tubes, diaper backsheets, tarpaulins, and geomembranes, which are used to line containment ponds and landfill pits. 

Sierralta M., Nowak M., and Keppler H. (2002) The influence of bulk composition on the diffusivity of carbon dioxide in Na aluminosilicate melts. Am. Mineral. 87, 1710-1716. 

Knudsen Diffusion Only Is Occurring. For a very fine pore material in which the effective pore diameter is less than the mean free path of the molecules, bulk diffusion and Poiseuille flow do not occur. For this case, the change in volume given when C + CO2 —> 2CO has no influence on the rate of diffusion of carbon dioxide into the rod, and is not dependent on the total pressure in the pores. Considering a wedge of carbon (Fig. Al),... 

The only published work on the diffusion of gas in coals of different rank appears to be that of Bolt and Innes (2) who studied the diffusion of carbon dioxide from eleven samples of coal at 38°C. They found the diffusion coefficient to range from 3.5 to 9.2 x 10 8 sq. cm./sec., with no apparent correlation with coal rank. Diffusion data on coals of different rank at temperatures higher than 38°C. have only been reported by the present authors (6). It has been shown (7) that the diffusion of inert or noble gases from coal above room temperatures can be rigorously analyzed by using simple diffusion theory, and that true diffusion parameters of the micropore systems can be obtained. In this paper our measurements on the unsteady state release of argon from coals of various rank, over a temperature range, are reported. 

Table IV also gives values of D and E for diffusion of carbon dioxide in 5A zeolite, calculated on the assumption that /+ = 1, using the values...

Vachon C, Tatibouet J (2004) Effect of additives on the solubility and diffusivity of carbon dioxide in polystyrene. Antec... 

Figure 2.3 Motion of a carbon dioxide molecule in a 6FDA-4PDA polymer matrix [8]. Reprinted from J. Membr. Sci. 73, E. Smit, M.H.V. Mulder, C.A. Smolders, H. Kar-renbeld, J. van Eerden and D. Feil, Modeling of the Diffusion of Carbon Dioxide in Polyimide Matrices by Computer Simulation, p. 247, Copyright 1992, with permission from Elsevier...

A deep pool of ethanol is suddenly exposed to an atmosphere consisting of pure carbon dioxide and unsteady state mass transfer, governed by Fick s Law, takes place for 100 s. What proportion of the absorbed carbon dioxide will have accumulated in the 1 mm thick layer of ethanol closest to the surface Diffusivity of carbon dioxide in ethanol = 4 x 10 9 m2/s. 

Michael Wasielewski of Northwestern University asked Thomas Moore about the type of light fluxes being used to investigate the solar flux. He also asked, Since we all know that photosynthesis has control mechanisms that actually modify electron flow, based on light flux, what kind of prospectus or perspective do we have for control mechanisms in such systems Moore explained that one of the factors that seems to limit natural photosynthesis is the diffusion of carbon dioxide into the system for fixing, so it is important in photosynthesis to throttle back the powerful oxidant when carbon dioxide is limiting. There is a control mechanism called nonphotochemical quenching that is related to the... 

Example 2.13 Estimation of diffusivity in a gas mixture at low pressure Estimate the diffusivity of carbon dioxide in benzene at 318 K and 1 atm. 

Example 2.16 Estimation of diffusivity of a component through a gas mixture Estimate the diffusivity of carbon dioxide (C02) through a gas mixture of benzene and methane with the known mole fractions given in the following table. The mixture is at 300 K and 2 atm. Welty et al. (1984)... 

Estimate diffusivity of carbon dioxide A in sulfur dioxide B at 263 and 473 K and 1 atm. The experimental values of diffusivities are (Griskey, 2002)... 

The diffusion of gases through a polymer matrix is determined by the mobility of gas molecules through the matrix. The diffusion coefficient is therefore, at least partially determined by the free volume size of the polymer. It has been shown, for example, that there is a correlation between the free volume measured by PAL and the diffusivity of carbon dioxide in a seriers of polycarbonates [58], In a study of poly (trimethylsilyl propyne) (PTMSP), which has an extremely high gas permeability and diffusion coefficients, it was found that the lifetime data could be resolved into four components [59]. The longest lifetime component (T4) had a lifetime of... 

O Leary M. H. (1984) Measurement of the isotope fractionation associated with diffusion of carbon-dioxide in aqueous-solution. J. Phys. Chem. 88(4), 823—825. 

Theoretical Predictions of Equilibrium Properties and Diffusivities of Carbon Dioxide in Type A Molecular Sieves... 

Diffusion of Carbon Dioxide in Type 5 A Molecular Sieve... 

The self-diffusion of carbon dioxide in single pellets of commercial type 5A molecular sieve has been studied using C 02 as a tracer. Experiments were carried out at atmospheric pressure between - -25° and —2S°C. Using a simple model of the pellet structure, it was possible to deduce effective diffusivities for both pore and crystal diffusion. Ordinary gas diffusion occurs in the pores crystal diffusivities have values of the order of 10 cm /sec. 

Wicke E and Kallenbach R. Surface diffusion of carbon dioxide in activated charcoals (Enghsh translation of the German title). 

There are various factors that predispose to decompression sickness. Some of these are obesity, age, exercise, and CO2 accumulation. In general, older individuals are more susceptible to decompression sickness than younger persons this is apparently related to the status of the circulatory system. Increased physical activity results in more rapid saturation of the tissues per unit time than in a resting individual. This increased rate of tissue saturation is due to the increased rate of ventilation and circulation resulting in more rapid transport of nitrogen to the tissues. Due to their very rapid circulation and ventilation, small animals are more resistant than man to decompression sickness. Blinks et al. (B28) found that increased CO2 tension in the tissues lowers the threshold for bubble formation. Although the mechanism of this phenomenon is not known, there is reason to suspect that it may be due to the high solubility and diffusibility of carbon dioxide (H5). 

Y. P. Tang Diffusion of Carbon Dioxide in Liquids—Concentration Dependence of Diffusion Coefficient and Diffusion in Mixed Solvents, Ph.D. Dissertation, University of Texas, 1963. 

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