Binary Mixtures—Low Pressure—Polar Components

Binary Mixtures—Low Pressure—Polar Components The Brokaw correlation was based on the Chapman-Enskog equation, but 0 g and were evaluated with a modified Stockmayer potential for polar molecules. Hence, slightly different symbols are used. That potential model reduces to the Lennard-Jones 6-12 potential for interactions between nonpolar molecules. As a result, the method should yield accurate predictions for polar as well as nonpolar gas mixtures. Brokaw presented data for 9 relatively polar pairs along with the prediction. The agreement was good an average absolute error of 6.4 percent, considering the complexity of some of... 

The first chiral separation using pSFC was published by Caude and co-workers in 1985 [3]. pSFC resembles HPLC. Selectivity in a chromatographic system stems from different interactions of the components of a mixture with the mobile phase and the stationary phase. Characteristics and choice of the stationary phase are described in the method development section. In pSFC, the composition of the mobile phase, especially for chiral separations, is almost always more important than its density for controlling retention and selectivity. Chiral separations are often carried out at T < T-using liquid-modified carbon dioxide. However, a high linear velocity and a low pressure drop typically associated with supercritical fluids are retained with near-critical liquids. Adjusting pressure and temperature can control the density of the subcritical/supercritical mobile phase. Binary or ternary mobile phases are commonly used. Modifiers, such as alcohols, and additives, such as adds and bases, extend the polarity range available to the practitioner. 

Whereas gas-gas equilibria had been a curiosity of phase theory as lately as 10 years ago they have now proved to be as important as the classical types of gas-liquid and liquid-liquid equilibria. They are not at all restricted to some special cases but represent the normal type of two-phase equilibrium in systems of components that differ considerably in size, shape, volatility, and polarity, and consequently show a low mutual solubility even up to rather high temperatures. Thus, fluid systems where the phase-separation effects have to be attributed to the solubility of gas in a liquid (or of a liquid in a gas) at normal conditions of temperature and pressure will frequently exhibit gas-gas critical phenomena at higher temperatures some examples for binary mixtures of He, N2, CH4, CO2, etc. with organic liquids and liquid water are given in Sections 2 and 3.f... 

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