Solvents fractionation

Yn + 1 = Mol fraction VOC component in the incoming fresh air (equals zero for fresh air) yj = Mol fraction solvent component in vapor Ys = Mol fraction steam in vapor YjB = Percent recovery of, i, in the bottoms YiD = Percent recovery of, i, in the distillate Z = Compressibility factor z F = Mol fraction component, i, in feed Zj Fj = Mol fraction component, i, in feed, j z s = Mol fraction component, i, in sidestream Zi sk = Mol fraction component, i, in sidestream, k... 

Molality Mass Percent Ppm Solvent Solute Mole Fraction Solvent... 

Figure 6. GPC chromatograms of phosphatidyl choline fraction (solvent THF columns 10 A + /O A -f 10 A + 500 A fjJStyragel flow rate 1.81 mL/min injection volume 25-250 fxL)...

Class fractionation Solvent exchange Fast extraction... 

Fish Extraction by column chromatography GPC fractionation solvent exchange fractionation of alkanes on silica gel column chromatography GC/MS Not specified Not specified Hesselberg and Seelye 1982... 

Fig. 2.9 Relative permittivities of water-organic solvent mixtures plotted against their volume fractions. Solvents open circles AN open triangles MeOH open squares THF filled circles DMSO filled triangles DMF filled squares Ac. (From the data in Table 7.1 Ref. [5])...

In numerous instances, additional processing may he required to remove stubborn impurities, waxes, colors, and notably terpene fractions. Solvent extraction is also used in processing herbs and spices to yield olenresins. 

Polynuclear aromatic hydrocarbons (PAH) (a coal-tar distillate fraction) — Solvent extraction and determination by HPLC, GC-FID or GC/MS enzyme immunoassay testing may be applied for semiquantitive determination. 

Substituting in the relation v.p. solution = (v.p. pure solvent) x (mole fraction solvent),... 

As previously mentioned, cyclohexane was chosen for the fractionation solvent for the second step, since it could transport sufficient quantities of residuum at reasonable temperatures. In the reflux mode, the column of the FDV is operated at a higher temperature than the extraction zone. As the carry-over of residuum decreases, the temperature of the column is reduced to cause the density in this region to increase and consequently more residuum is transported overhead. 

Purification can also be achieved in other ways, through precipitation with salts, crystallization, and through aqueous two-phase extraction. Some of these methods are associated with substantial capital cost, low throughput, low yields, or waste issues. Fractional precipitation, one of the oldest protein separation technologies, can be surprisingly effective to separate a compound of interest from a complex broth. For instance, the process of fractional solvent precipitation of blood plasma components has been used since World War II. 

It has been shown that n (O2) for R1 is in fact proportional to the fractional solvent accessibility ( Jsa) of the native side chain at the same site computed from the corresponding crystal structure (Isas et al., 2002). The sequence dependence of the solvent accessibility, measured by either fsa or n (O2), is a fingerprint for a protein fold. For example, solvent accessibility is periodic through regular secondary structure, and the period and phase of the function identify the type of secondary structure and its orientation in the protein, respectively. In nonregular secondary structure encountered in loops, the solvent accessibility is not necessarily periodic, but the functional dependence on sequence remains characteristic of the fold. Thus, comparison of a computed from a crystal structure and n (O2) determined experimentally for the protein in solution is a convenient and efficient way of comparing the solution and crystal structures. This will be the method used below for rhodopsin. 

C2 constitutes part of the transducin interaction domain (Fig. IB). Figure 10A shows the sequence in C2, TM3, and TM4 (136-155) that has been investigated by cysteine scanning mutagenesis and SDSL (Ridge et at., 1995 Farahbakhsh et al., 1995). Figure 10B (upper panel) shows the fractional solvent accessibilities for residues in the 136-155 sequence... 

The method can be used for weight fractions of solvent up to 0.75, but the data become very unreliable in this range and small temperature fluctuations cause large swings in the data. A more reasonable upper limit is 0.5 weight fraction solvent. 

Entry Fractionalization Temperature CQ Fractionalization Solvent Molecular Weight (daltons) PDI... 

In summary, this example shows how the change in the operating parameters effects the component cost. The higher yields lead to lower fractional lost-crude cost, the higher production rate to lower labor cost. The higher flow rate results in higher fractional solvent cost and system cost. 

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