Displacement chromatography calculations

Frenz, J., and Horvath, Cs. (1985). High Performance Displacement Chromatography Calculation and experimental verification of zone development. AIChE J. 31, 400-409. 

Example 12 Calculation of Band Profiles in Displacement Chromatography Au equimolar mixture of two compoueuts (couceutra-tious cf = = 1 arbitrary iiuit) is separated with a displacer with couceutratiou... 

Hydrocarbon types were estimated using the substractive method of Poulson (15,16) for the fractions boiling above 175°F. The hydrocarbon compound composition of the C5-175°F naphtha was determined by gas chromatography. Paraffin and naphthene contents of the 175°-350°F naphtha and of the 350°-550°F light oil were calculated from mass spectra. Liquid displacement chromatography on Florisil was used to determine the amount of polar material in the 550°-850°F heavy oil. 

Kaldsz, H. Bathori, M. Spacer displacement chromatography of steroids. Experiments, considerations and calculations. Invertebr. Reprod. Dev. 1990, 18, 119-120. 

The profiles of individual zones in displacement chromatography have also been calculated using the solid film linear driving force model [23]. Again, when the number of mass transfer units of the column is high, the results are very similar to those obtained with the equilibrium-dispersive model (Chapter 12). As an example. Figure 16.10 shows the displacement chromatogram calculated with kpi = kfg = = 50 s . The bands in the isotachic train are clearly formed... 

Figure 16.10 Calculated zone profiles in displacement chromatography, fcy j = fc/,2 = fc/,d = 50 s. Solid gray line first component thin solid black line second component fat solid black line displacer. Characteristic of the separation Column length 25 cm. Phase ratio 0.25. Flow velocity 0.05 cm/s. Competitive Langmuir isotherm with coefficients = 18.75 fl2 = 22.5 = 27 bi = 12.5 i>2 = 15 bj = 18 2,1 = 1.20. Loading factors Ly =...

Figure 16.11 Calculated zone profiles in displacement chromatography. Same as in Figure 16.10, except = kfg = kf, j = 0.2 s. Reproduced with permission from S. Golshan-Shirazi and G. Guiochon, Anal. Chem., 61 (1989) 1960 (Fig. 11). 1989, American Chemical Society.

Dipole interact ions,. tee Electrostatic forces Dispersion forces (energies), 44-47 on alumina, 245 in gas-solid adsorption, 243-245 Displacement chromatography, 34-36 Distribution coefficient A, lOi-ll calculation (examples), 385-396 correlation between different adsorbent batches, 148-149... 

In almost all cases, the experiments yielded values a> 1. The heavier isotope is enriched in the solution phase and is eluted first. The theory of isotope separation by elution chromatography and the procedure for the calculation of the separation factor from experimental data was elaborated by Glueckauf. For the case of displacement chromatography the theory was developed by Kakihana and Oi. 

The molecular migration pathway in chromatography is a statistical pathway in which each molecule randomly executes the steps that constitute its particular migration path. If it were possible to outline the choices faced by a molecule (such as whether or not to adsorb in a given time interval or which streampath to follow around a particle), and the probability of each option, we would in theory be able to calculate the probability that the molecule would follow a particular path. Since all identical molecules are identically inclined, the probability of a certain path for a single molecule is equal to the fraction of all molecules taking that path. If, for instance, the probability is known for two paths, one displacing the molecule 20 mm and... 

Thus, we can conclude that, as long as the mass transfer kinetics is reasonably fast, the equilibrium-dispersive model can be used as a first approximation to predict shock layer profiles. As a consequence, the results of calculations of band profiles, breakthrough curves, or displacement chromatograms made with this model can be expected to agree well vsdth experimental results. Conclusions based on the s) stematic use of such calculations have good predictive value in preparative chromatography. 

Acid-base properties of oxide surfaces are employed in many fields and their relationship with PZC has been often invoked. Adsorption and displacement of different organic molecules from gas phase was proposed as a tool to characterize acid-base properties of dry ZnO and MgO [341]. Hammet acidity functions were used as a measure of acid-base strength of oxides and some salts [342]. Acidity and basicity were determined by titration with 1-butylamine and trichloroacetic acid in benzene using indicators of different pAg. There is no simple correlation between these results and the PZC. Acid-base properties of surfaces have been derived from IR spectra of vapors of probe acids or bases, e.g. pyridine [343] adsorbed on these surfaces. The correlation between Gibbs energy of adsorption of organic solvents on oxides calculated from results obtained by means of inverse gas chromatography and the acceptor and donor ability of these solvents was too poor to use this method to characterize the donor-acceptor properties of the solids [344],... 

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