Diffusion coefficients chloride

The sedimentation and diffusion coefficients for three different preparations of poly(methyl methacrylate) were measuredf in /i-butyl chloride at 35.6 C (= 0) and in acetone at 20 C (> 0) and the following results were obtained ... 

Fig. 37. Diffusion coefficient as a function of molar volume for a variety of permeants in natural mbber and in poly(vinyl chloride) (PVC) (81—83).

Humidity does not affect the permeabihty, diffusion coefficient, or solubihty coefficient of flavor/aroma compounds in vinyhdene chloride copolymer films. Studies based on /n j -2-hexenal and D-limonene from 0 to 100% rh showed no difference in these transport properties (97,98). The permeabihties and diffusion coefficients of /n j -2-hexenal in two barrier polymers are compared in Table 12. Humidity does not affect the vinyhdene chloride copolymer. In contrast, transport in an EVOH film is strongly plasticized by humidity. 

Table 10 contains some selected permeabiUty data including diffusion and solubiUty coefficients for flavors in polymers used in food packaging. Generally, vinyUdene chloride copolymers and glassy polymers such as polyamides and EVOH are good barriers to flavor and aroma permeation whereas the polyolefins are poor barriers. Comparison to Table 5 shows that the large molecule diffusion coefficients are 1000 or more times lower than the small molecule coefficients. The solubiUty coefficients are as much as one million times higher. Equation 7 shows how to estimate the time to reach steady-state permeation t if the diffusion coefficient and thickness of a film are known. 

Permeation in the vinyUdene chloride copolymer and the polyolefins is not affected by humidity the permeability and diffusion coefficient in the ethylene—vinyl alcohol copolymer can be as much as 1000 times greater with high humidity (14—17). 

The permeability tests for alkali metal ions in the aqueous solution were also conducted. When an aqueous salt solution moves to cell 2 through the membrane from cell 1, the apparent diffusion coefficient of the salt D can be deduced from a relationship among the cell volumes Vj and V2, the solution concentration cx and c2, the thickness of membrane, and time t6 . In Table 12, permeabilities of potassium chloride and sodium chloride through the 67 membrane prepared by the casting polymerization technique from the monomer solution in THF or DMSO are compared with each other and with that the permeability through Visking dialyzer tubing. The... 

The amount of hydrogen chloride captured as sodium chloride was proportional to square root of time and sodium diffusion coefficients in glass cullets calculated were 2.9 - 3.9xl0 m /s at 823K. Also, chlorine-firee char can be produced by steam decomposition, even though particle size issue remains. 

FIG. 18 Chloride concentration profile recorded by a microelectrode probe during the hydrolysis of TPMCl at a DCE drop-aqueous interface (O)- The concentration of TPMCl in the organic phase was 50 mmol dm, the drop time from formation to contact with the probe was 4.80 s, and the final drop radius was 0.55 mm. The solid lines represent theoretical time-dependent concentration profiles, from top to bottom, generated for k = 3.50 x 10 , 3.25 x 10 , and 3.00 x 10 molcm s . A value of 1.8 X 10 cm s was employed for the diffusion coefficient of chloride. (Reprinted from Ref. 73. Copyright 1997, American Chemical Society.)... 

Traditionally, the penetration of chlorides and sodium is measured destructively by grinding layers of concrete and chemically analyzing the powder samples. These data are used to calculate diffusion coefficients for the ions. This procedure is very slow, has low spatial resolution, and is destructive. The measured data are critically important for the development of service life models and therefore a rapid, high-resolution method to monitor the ingress of these ions is desirable. 

Figure 5 The mutual diffusion coefficient, D, of sodium chloride as a function of reciprocal matrix hydration, H, in various methacrylate gels. HPMA-GMA polyfhydroxypro-pyl methacrylate-co-glyceryl methacrylate) HEMA polyfhydroxyethyl methacrylate) MMA-GMA poly(methyl methacrylate-co-glyceryl methacrylate) HEMA-MMA poly-(hydroxyethyl methacrylate-co-methyl methacrylate) HPMA-MMA polyfhydroxypropyl methacrylate-co-methyl methacrylate) HPMA-GDMA polyfhydroxypropyl methacry-late-co-glyceryl dimethacrylate). (From Ref. 64.)...

Up to now, no direct measurements of diffusion coefficients have been reported for any system that show the low-temperature upturn just described, and it may well be that for most systems involving hydrogen such effects would occur only at ultra-low temperatures and minuscule diffusion rates. Also, the impurities and imperfections always present in real materials might well trap nearly all the diffusant atoms at the low temperatures at which coherent transport might be expected in ideal material. However, a recent measurement by Kiefl et al. (1989) of the (electronic) spin relaxation rate of muonium in potassium chloride over a range of temperatures gives spectacular support to the concept of coherent tunneling at low temperatures. (See Fig. 6 of Chapter 15 and the associated discussion.)... 

Chlorine (Cl), 6 130-211 9 280. See also Inorganic chlorine XeCl laser addition to fullerene, 12 240-241 analytical methods, 6 202 bleaching agent, 4 50 capacities of facilities, 6 193-198t catalyst poison, 5 257t chemical properties, 6 133-138 diffusion coefficient for dilute gas in water at 20° C, l 67t diffusion coefficient in air at 0° C, l 70t for disinfection, 8 605 economic aspects, 6 188-202 electrolytic preparation/production of, 12 759 16 40 end uses, 6 134-135 in fused quartz manufacture, 22 413 generating from hydrogen chloride, 13 833... 

Figure Bll.2.1 shows the normalized autocorrelation functions of various micelles loaded with octadecyl rhodamine B chloride (ODRB) at pH 7 (PBS buffer)3 . The differences in size of the micelles are clearly reflected by the differences in diffusion times td- The translational diffusion coefficients are reported in Table Bll.2.1, together with the hydrodynamic radii and the aggregation numbers.

The diffusion coefficients of potassium and sodium chlorides in the membrane we have found to be independent of solution concentration within experimental error. The value of sodium chloride agrees well with those found by others bearing in mind the differences in the polymer and in the membrane casting procedures (5,13). 

Fell G.J.D. and Hutchison H. P. (1971) Diffusion coefficients for sodium and potassium chlorides in water at elevated temperatures. J. Chem. Eng. Data 16, 427-429. 

Figure 6.29 Diffusion coefficient measured directly (open circles) and calculated from electrical conductivity data (closed circles) for Na+ in sodium chloride. From W. D. Kingery, H. K. Bowen, and D. R. Uhhnann, Introduction to Ceramics. Copyright 1976 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

For similar solvent polymeric membranes (78 wt.% dicresyl butyl phosphate in polyvinyl chloride) self-diffusion coefficients of the order of 10-7 cm2s 1 have been reported.12 These diffusion coefficients, as well as measurements of rotational mobilities,14 indicate that the solvent polymeric membranes studied here are indeed liquid membranes. This liquid phase is so viscous, however, that convective flow is virtually absent. This contrasts with pure solvent membranes where an organic solvent is interposed between two aqueous solutions either by sandwiching it between two cellophane sheets or by fixing it in a hole of a Teflon sheet separating the aqueous solutions.15 The extremely high convective flow is one of the reasons why the term membrane for extraction systems... 

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