Partition ratio

Elution volume, exclusion chromatography Flow rate, column Gas/liquid volume ratio Inner column volume Interstitial (outer) volume Kovats retention indices Matrix volume Net retention volume Obstruction factor Packing uniformity factor Particle diameter Partition coefficient Partition ratio Peak asymmetry factor Peak resolution Plate height Plate number Porosity, column Pressure, column inlet Presure, column outlet Pressure drop... 

Partition Ratio. The partition ratio is the additional time a solute band takes to elute, as compared with an unretained solute (for which k = 0), divided by the elution time of an unretained band ... 

Partition coefficients Partition ratio Parts Parure... 

Equations 17—20 result from contact between hot metal and slag, and the sulfur and carbon come dissolved in the hot metal. Likewise, the manganese, siUcon, and phosphoms which are produced are dissolved into the hot metal. The heats of solution for these elements in some cases depend on concentration, and are not included in the heats of reaction Hsted above. The ratio of the concentration of the oxide (or element for sulfur) in the slag to the concentration of the element in the hot metal is the partition ratio, and is primarily a function of slag chemistry and temperature. 

Fig. 12. The relationship between the mean oceanic residence time, T, yr, and the seawater—cmstal rock partition ratio,, of the elements adapted from Ref. 29. , Pretransition metals I, transition metals , B-metals , nonmetals. Open symbols indicate T-values estimated from sedimentation rates. The sohd line indicates the linear regression fit, and the dashed curves show the Working-Hotelling confidence band at the 0.1% significance level. The horizontal broken line indicates the time required for one stirring revolution of the ocean, T. ...

The efficiency of inactivation by covalent bond formation vs release of the reactive species into solution has been described by its partition ratio. The most efficient inactivators have catalytic partition ratios of 0, in which case each inhibitor molecule leads to inactivation of the enzyme. To this date, many of these inhibitors have been designed, and alternative names like suicide substrate, Trojan Horse inactivator, enzyme induced inactivator, inhibitor, and latent inactivator have been used for this class of inhibitors. A number of comprehensive reviews are available (26—32). 

The weight fraction of solute in the extract phase y divided by the weight fraction of solute in the raffinate phase x at equilibrium is called the partition ratio, K [Eq. (15-1)]. 

Thermodynamically the partition ratio K° is derived in mole fractions... 

For shortcut calculations the partition ratio K in Bancroft [Phys. Rev., 3, 120 (1895)] coordinates using the weight ratio of solute to extraction solvent in the extract phase Y and the weight ratio of solute to feed solvent in the raffinate phase X is preferred [Eq. (15-3)]. 

The value of K is one of the main parameters used to establish the minimum ratio of extraction solvent to feed solvent that can be employed in an extraction process. For exanmle, if the partition ratio K is 4, then a countercurrent extractor woula require 0.25 kg or more of extraction-solvent flow to remove all the solute from 1 kg of feed-solvent flow. 

The relative separation, or seleetivity, Ot between two components, h and c, can be described by the ratio of the two partition ratios... 

Multicomponent systems containing four or more components become difficult to display graphically. However, process-design calculations can often be made for the extraction of the component with the lowest partition ratio K and treated as a ternaiy system. The components with higher K values may be extracted more thoroughly from the raffinate than the solute chosen for design. Or computer calculations can be used to reduce the tedium of multicomponent, multistage calculations. 

Consequently, the partition ratio in mole-fraction units is a result of the ratio of activity coefficients in the two layers [Eq. (15-7)]. 

Gmehhng and Onken (Vapor-Liquid Equilibrium Data Collection, DECHEMA, Frankfurt, Germany, 1979) have reported a large collection of vapor-liqnid equilibrium data along with correlations of the resulting activity coefficients. This can be used to predict liqnid-hqnid equilibrium partition ratios as shown in Example 1. 

Example 1 Partition Ratios Let us estimate the partition ratio in weight fractions K for extracting low concentrations of acetone from water into chloroform. The solute is acetone, the feed solvent is water, and the extraction solvent is chloroform in this case. 

Gmehhng and Onken (op. cit.) give the activity coefficient of acetone in water at infinite dilution as 6.74 at 25 C, depending on which set of vapor-liquid equilibrium data is correlated. From Eqs. (15-1) and (15-7) the partition ratio at infinite dilution of solute can he calculated as follows ... 

Sorenson and Arlt Liquid-Liquid Equilihiium Data Collection, DECHEMA, Frankfurt, Germany, 1979) report several sets of liquid-liquid equilibrium data for the system acetone-water-chloroform, but the lowest solute concentrations reported at 25 C were. 3 weight percent acetone in the water layer in equilibrium with 9 weight percent acetone in the chloroform layer. This gives a partition ratio K of, 3.0. 

A negative deviation reduces the activity of the solute in the solvent, which enhances the liqnid-hqnid partition ratio but also leads to maximnm-boihng-point azeotropes. Among other classes of solvents shown in Table 15-4 that suppress the escaping tendency of a ketone are classes 1 and 2, i.e., phenohcs and acids. 

Wisniak and Tamir Liquid-Liquid Equilihiium and Extraction A Literature Source Book, Elsevier, Amsterdam, 1980) have hsted many references. Leo, Hansch, and Elkins [Chem. Rev., 71(6), 525 (1971)] have tabulated partition ratios for a large number of solutes between water and solvents. Table 15-5 gives a selec ted list of partition ratios. 

Paiiition ratio. The partition ratio for a solute should preferably be large so that a low ratio of extraction solvent to feed can be used. 

Component A = feed solvent, component B = solute, and component S = extraction solvent. K is the partition ratio in weight-fraction solute if/x for the tie line of lowest solute concentration reported. Ordinarily, K will approach unity as the solute concentration is increased. 

The working capacity of a sorbent depends on fluid concentrations and temperatures. Graphical depiction of soration equilibrium for single component adsorption or binary ion exchange (monovariance) is usually in the form of isotherms [n = /i,(cd or at constant T] or isosteres = pi(T) at constant /ij. Representative forms are shown in Fig. I6-I. An important dimensionless group dependent on adsorption equihbrium is the partition ratio (see Eq. 16-125), which is a measure of the relative affinities of the sorbea and fluid phases for solute. 

The 0.865 factor is used to match this equation to the Brenner and Gaydos expression for = 0.2. In these cases, the pore concentration Cpi is related to the external concentration Cj by the partition ratio... 

Commonly used forms of this rate equation are given in Table 16-12. For adsorption bed calculations with constant separation factor systems, somewhat improved predictions are obtained using correction factors f, and fp defined in Table 16-12 is the partition ratio... 

Determination of Controlling Rate Factor The most important physical variables determining the controlhng dispersion factor are particle size and structure, flow rate, fluid- and solid-phase diffu-sivities, partition ratio, and fluid viscosity. When multiple resistances and axial dispersion can potentially affect the rate, the spreading of a concentration wave in a fixed bed can be represented approximately... 

This important dimensionless group is the volumetric capacity of the bed for the sorbable component divided by the concentration of the sorbable component in the feed. The stoichiometi ic capacity of the bed for solute is exactly equal to A empty bed volumes of feed (to saturate the sorbent at the feed concentratiou) plus a fraction of a bed volume of feed to fill the voids outside and inside the particles. Alternatively, we also obtain Eq. (16-124) using the dimensionless transition variables for concentrations [Eq. (I6-II)], but now the partition ratio in the first term of Eq. (16-124) pertains to the transition and is given by... 

The terms partitioning ratio and commitment factor are also found. 

Parallel reactions, 58-64, 129 Partitioning ratios, 79 Perturbation (see Chemical relaxation) pH profiles, 139-145 bell-shaped, 141-142 Phosphorous acid, oxidation of, 186-187 Physical methods for kinetics, 22-25 end point reading unknown, 25-28 sample calculation for, first-order,... 

Allard A-S, L Renberg, AH Neilson (1996) Absence of evolution from -labelled EDTA and DTPA and the sediment/water partition ratio using a sediment sample. Chemosphere 33 577-583. 

With a 3,3-heterodihalogeno substitution of the (3-lactam ring, a selective interaction of each enantiomer of the chiral azetidinone with the enzyme active site is expected. The enantiomer 3R of the 3F, 3Br derivative indeed has a more favorable kinetic parameter k-JK, than the enantiomer 3S.33 The partition ratio kCA /kt (=k3/k4, Eq. 11.1) for the inactivation is also higher. Therefore, enantiomer 3R is a better suicide substrate for HLE since a lower partition ratio corresponds to abetter suicide substrate.20... 

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