Symmetric separator

For a symmetrical separation of component h from c, Brian Staged Cascades in Chemical Processing, Prentice-Hall, Englewood Cliffs, N.J., 1972) reported that the ratio of wash solvent to extraction solvent W /S should be set equal to the geometric mean of the two slopes of the equilibrium lines [Eq. (15-35)]. 

Figure Three represernarions of the structure of Cm- (a) normal ball-and-stick model (b) the polyhedron derived by truncating the 12 vertices of an icosahedron to form 12 symmetrically separated pentagonal faces (c) a conventional bonding model.

Total reflux for a symmetric separation. Note, the term symmetric separation is used here to mean that on a McCabe-Thiele diagram, the liquid phase compositions of the overhead product and bottom product are roughly equidistant from 0.5. 

The activation energy for a symmetrical separation of polymer chain centers by a distance of z over a length x is given by (12),... 

Proteins in homogenized dairy products Symmetrical Separation of whey proteins from fat globules fractionation of whey proteins and casein micelles effect of carrier ionic strength, cross-flow rate, pH, and membrane type on retention and size distribution of micelles [M. A. Jussila, G. Yohannes, and M.-L. Riekkola, J. Microcol. Separ. 9 601-609 (1997)]... 

Lipoproteins in human plasma Symmetrical Separation of low-MW proteins, HDL, LDL, and VLDL Determination of subspecies in the Apoprotein fractions with linear programmed cross-flow rate observation of Apoprotein proflles for different individuals [10]... 

Early in a project, it may be useful to consider a simplified case in which the ratio of extraction solvent to wash solvent is constant and the same in the stripping and washing sections (i.e., the amount of solvent entering with the feed is negligible) and the extraction factors for each section are equal. For this special case, termed a symmetric separation, the extraction factors are... 

In order to obtain the energy needed for the symmetric separation of two chains required for the passage of a penetrant molecule, the chains are assumed to interact according to the DiBenedetto potential, which takes the chain to be a sequence of... 

The sample is usually added to the column in a small volume of a weak solvent, and the solution forced into the sorbent bed forming a narrow sample band. For samples of low solubility in weak solvents, the sample is taken up in a strong solvent and added to a small amount of column packing or other inert support. The solvent is then stripped from the slurry under vacuum to produce a dry free-flowing powder (1-2 g sample / g sorbent) that can be added to the top of the column. It is important that the sample is completely dry (high vacuum used to remove last traces of solvent), and free of lumps, to obtain symmetrical separated bands. If the sample layer is relatively long compared... 

Illustration 3. Scheibel (15) reports the simultaneous distribution of para (B)- and ortho (C)-chloronitrobenzene between the double-solvent pair Skellysolve (a mixture of heptanes) (2I) and methanol (containing 15% water by volume) (D). When 50 gm. of solute was distributed between 250 cu. cm. of each of the solvents, = 1.33 and me = 0.82, values which are substantially constant with varying ratios of the distributed substances. The solvents are subsjbantially immiscible. What will be the solvent-free product compositions when 100 lb. of a mixture containing 33.5% para-, 66.5% ortho-chloronitrobenzene are distributed in a single-stage extraction with these solvents to give (o) a symmetrical separation and (6) products of equal purity What quantities of the solvents should be used ... 

Estimates of extractions can be made quickly with the assistance of Fig. 7.17, which relates the fraction of either solute which has accumulated in the composited il-rich layers with the number of stages in a diamondshaped plan. For symmetrical separations, the abscissa for ps is the degree of separation as defined by Eq. (7.38). 

Illustration 4. p-Nitrobenzoic acid (B) and o-nitrobenzoic acid (C) distribute between chloroform (A) and water (D) (mutually saturated solvents) with distribution coefficients = 1.71 and me = 0.27 at concentrations of 0.0015 gm. mole/liter in the A-rich layer, at 25 C. ( International Critical Tables, Vol. Ill, p. 429). On the assumption that the distributions are independent of each other, calculate the separation obtainable for various numbers of stages and for a symmetrical separation, starting with a 60-50 mixture of B and C. 

Illustration 8. Van Dijck and Schaafsma (18) report on the simultaneous distribution of para (B)- and ortho (C)-ethoxy aniline between the double solvent 50% aqueous ethanol (A), hydrocarbon (50% gasoline, 50% benzene) (I>). When 20 gm. of mixture is distributed between 100 cu. cm. each of the solvents, — 4.85, me = 0.74. Assuming that the distribution coefficients are constant and independent, (a) what purity of products will be obtained for a solvent ratio of 1 1 by volume for a feed consisting of a 50-50 mixture of the solutes introduced centrally into a five-stage cascade (h) What purity will result for a five-stage cascade where n = 2, n = 3 (c) What solvent ratio is required for a symmetrical separation ... 

For a symmetrical separation with the same number of stages in the lightweight and heavy particle flow (zl = zs = z), the total separation function can be simplified with Eqs.(l) and (2) to [16,17] ... 

Example 2.2.1 Obtain simplified expressions of for (a) close separation, (b) a close-separation symmetrical separator and (c) a dilute solution of species 2 in solvent 1. 

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