Fig. 15. Theoretical breakthrough curves for a nonlinear (Langmuir) system showing the comparison between the linear driving force (—), pore diffusion (--------------------), and intracrystalline diffusion (-) models based on the Glueckauf approximation (eqs. 40—45). From Ref. 7. Fig. 15. Theoretical breakthrough curves for a nonlinear (Langmuir) system showing the comparison between the linear driving force (—), pore diffusion (--------------------), and intracrystalline diffusion (-) models based on the Glueckauf approximation (eqs. 40—45). From Ref. 7.
For linear or moderately nonlinear systems (/5 — 1.0) there is Htde difference in the response curves for all three models, thus verifying the vaUdity of the Glueckauf approximation. Differences between the models, however, become more significant for a highly nonlinear isotherm (/5 — 0). For linear or near linear systems the adsorption and desorption curves are mirror images, but as the isotherm becomes more nonlinear the adsorption and desorption curves become increasingly asymmetric. The adsorption curve approaches its limiting constant pattern form whereas the desorption curve approaches the limiting proportionate pattern form. In the long-time region the desorption curve is governed entirely by equiUbrium, so that the curves for all three rate models again become coincident.  [c.264]

The main conclusion to be drawn from these studies is that for most practical purposes the linear rate model provides an adequate approximation and the use of the more cumbersome and computationally time consuming diffusing models is generally not necessary. The Glueckauf approximation provides the required estimate of the effective mass transfer coefficient for a diffusion controlled system. More detailed analysis shows that when more than one mass transfer resistance is significant the overall rate coefficient may be estimated simply from the sum of the resistances (7)  [c.264]

E. Glueckauf, Trans. Faraday Soc. 51, 1540 (1955).  [c.268]

F. M. Fess, EListory of Coke Oven Technology, Gluckauf Vedag, Essen, Germany, 1957.  [c.76]

T. F. Johns, in Ref. 5, Section II-5.2, pp. 123—142 E. Glueckauf, in Ref. 5, Section II-5.6, pp. 209—248.  [c.199]

Gelatin Costing. A more recent development in tablet coating involves the use of gelation as the coating material to produce geltabs. If a tablet is compressed as a capsule-shaped unit prior to gelatin coating it is called a gelcap. Such tablets are dipped into a reservoir of a molten gelatin mixture, similar to the production of empty, hard gelatin capsule shells. The gelatin coating faciUtates swallowing.  [c.230]

The linear driving force (LDF) approximation is obtained when the driving force is expressed as a concentration difference. It was originally developed to describe packed-bed dynamics under linear eqm-librium conditions [Glueckauf, Trans. Far Soc., 51, 1540 (1955)]. This form is exact for a nonlinear isotherm only when external mass transfer is controlling. However, it can also be used for nonlinear sys-  [c.1514]

A,3A. Glueckauf and Coates,/ Chem. Soc., 1315 (1947) Trans. Faraday Soc., 51, 1540 (1955) Hall et al., Ind. Eng. Chem. Eundam., 5, 212 (1966) 2B. Vermeulen, Ind. Eng. Chem., 45, 1664 (1953)  [c.1515]

After its initial introduction, the plate theory was further elaborated by Mayer and Tomkins (1947). [2] and Glueckauf (1955) [3] but it was not until 1956 that Said [4] generated the more precise and useful form that is generally used today. Said s treatment furnished a simple differential equation that could be integrated to give a Poisson function which, under limiting conditions, simplified to a Gaussian or Error function. It will be seen that the Gaussian or Error function curve is the generally accepted characteristic shape of an ideal chromatography elution curve. At the time of publication, the work of Said went almost unnoticed by the chromatography field and this more useful form of the plate theory was not generally known or appreciated until reported and discussed by Keulemans [5] in 1959.  [c.5]

Gelation characteristics Gelation point Gelcap Gel coats Geldan aldehyde Geldanamycin  [c.436]

Also shown are the corresponding curves calculated for the same system assuming a diffusion model in place of the linear rate expression. For intracrystalline diffusion k = 15Dq/v, whereas for macropore diffusion k = 15e /R ) Cq/q ), in accordance with the Glueckauf approximation (21).  [c.264]

Several examples of cost-effective liquid-hquid extraction processes include the recovery of acetic acid from water (Fig. 15-1), using ethyl ether or ethyl acetate as described by Brown [Chem. Eng. Prog., 59(10), 6.5 (1963)], or the recoveiy of phenolics from water as described by Lauer, Littlewood, and Butler [7/Steel Eng., 46(5), 99 (1969)] with butyl acetate, or with isopropyl ether as described by Wurm [Gliickauf, 12, 517 (1968)], or with methyl isobutyl ketone as described by Scheibel [ Liqmd-Liquid Extraction, in Periy Weiss-  [c.1448]

D Glueckauf Coates,y, Chem. Soc., 1947, 1315 (1947) VeYme Aen, Advances in Chemical Engineeiing, 2, 147 (1958) Hall et al., Ind. Eng. Chem. Fundam., 5, 212 (1966) Miura and Hashimoto,y, Chem. Eng. Japan, 10, 490 (1977).  [c.1527]

Membrane electrophoresis which is based upon differences in ion mobility, has been studied by Glueckauf and Kitt [J. Appl. Chem., 6, 511 (1956)]. Partial exclusion of coions by membranes results in large differences in coion mobihties. Superposing a cation and an anion membrane gives high transference numbers (about 0.5) for both cations and anions while retaining the selectivity of mobihties. Large voltages are required, and flow rates are low.  [c.2007]

The former is to protect the human body from shock,s and electrocution, while the latter protects the circuit from fire risk. Normally the 300 mA GLCB is used as the incomer and 30 mA as the outgoing for the individual feeding circuits.  [c.680]

The theory of operation of a ground leakage circuit breaker (GLCB) is also the same as the combination of i core-balanced CT and a ground leakage relay. For industrial application, itse of a core-balanced CT with a ground leakage relay and for domestic application use of a GLCB is more eommon.  [c.685]

The original Rate Theory which describes dispersion in packed beds evolved over a number of years, probably starting with the work of Lapidus and Amundson [6] in 1952, extended by that of Glueckauf [7] and Tunitski [8] in 1954. The final form of the equation that described dispersion in packed beds as a function of the linear  [c.5]

See pages that mention the term GaAlSb : [c.36]    [c.228]    [c.336]    [c.448]    [c.328]    [c.328]    [c.509]    [c.263]    [c.347]    [c.356]    [c.31]    [c.134]    [c.299]    [c.299]    [c.299]    [c.364]    [c.534]    [c.170]    [c.316]    [c.248]    [c.197]    [c.197]    [c.197]    [c.205]    [c.205]    [c.205]    [c.205]    [c.206]    [c.206]    [c.77]    [c.471]    [c.392]   
Encyclopedia of materials characterization (1992) -- [ c.393 ]