Liquid solutions packing fraction

The ether solution and fractions taken during the subsequent distillation may be assayed by gas-liquid partition chromatography on a 0.8-cm. x 200-cm. column heated at 120° and packed with nonyl phthalate supported on ground firebrick. 

This is a typical laboratory apparatus for the fractional distillation of a liquid solution to obtain pure liquid components. The fractionating column contains a packing material, such as glass beads, on which vapor condenses and liquid redistills. The stopper on the receiver is loosely fitted to allow ventilation to the atmosphere. 

At least in the case of liquid simple metals, a knowledge of the effective pan-potentials describing the interaction between the ions in the liquid metal can also be utilized to calculate g(r) and A K). The most common such method involves the assumption of a hard-sphere potential in the Percus-Yevick (PY) equation its solution provides the hard-sphere structure factor, /4hs( C). (See Ashcroft and Lekner 1966.) The two parameters that must be provided for a calculation of Ahs( ) are the hard-sphere diameter, a, and the packing fraction, x. It is found that j = 0.45 for most liquid metals at temperatures just above their melting points. A hard-sphere solution of the PY equation has also been obtained for binary liquid metal alloys, and provides estimates of the three partial structure factors describing the alloy structure (Ashcroft and Langreth 1967). To the extent that the hard-sphere approximation appears to be valid for the liquid R s, pair potentials should dominate these metals also, at least at short distances. 

Mol fraction in liquid phase Equilibrium mol fraction in liquid phase Mol fraction in liquid film at interface Mol fraction solute in inlet liquid Mol fraction solute in outlet liquid Mol fraction in gas phase Equilibrium mol fraction in gas phase Mol fraction solute in inlet gas Mol fraction solute in outlet gas Packed depth (ft)... 

Mol fraction solute in extract liquid film Mol fraction solute in feed Mol fraction solute in raffinate Equilibrium mol fraction solute in raffinate Mol fraction solute in raffinate liquid film Packed depth (ft)... 

HOPC uses a column packed with porous materials that have a pore diameter close to a dimension of the solvated polymer to separate. A concentrated solution of the polymer is injected into the solvent-imbibed column by a high-pressure liquid pump until the polymer is detected at the column outlet. The injection is then switched to the pure solvent, and the eluent is fractionated. A schematic of an HOPC system is illustrated in Fig. 23.1. A large volume injection of a concentrated solution makes HOPC different from conventional SEC. 

Preparation of cholesta-5,7-diene-ia,3/3-diol a solution of 500 mg of the 1,4-cyclized adduct of cholesta-5,7-dien-3/3-ol-ia,2a-epoxideand 4-phenyl-1,2,4-triazoline-3,5-dione in 40 ml of tetrahydrofuran is added dropwise under agitation to a solution of 600 mg of lithium aluminum hydride in 30 ml of THF. Then, the reaction mixture liquid Is gently refluxed and boiled for 1 hour and cooled, and a saturated aqueous solution of sodium sulfate is added to the reaction mixture to decompose excessive lithium aluminum hydride. The organic solvent layer is separated and dried, and the solvent Is distilled. The residue Is purified by chromatography using a column packed with silica gel. Fractions eluted with ether-hexane (7 3 v/v) are collected, and recrystallization from the methanol gives 400 mg of cholesta-5,7-diene-la, 3/3-diol. 

Fig. 4.18 represents a countercurrent-flow, packed gas absorption column, in which the absorption of solute is accompanied by the evolution of heat. In order to treat the case of concentrated gas and liquid streams, in which the total flow rates of both gas and liquid vary throughout the column, the solute concentrations in the gas and liquid are defined in terms of mole ratio units and related to the molar flow rates of solute free gas and liquid respectively, as discussed previously in Sec. 3.3.2. By convention, the mass transfer rate equation is however expressed in terms of mole fraction units. In Fig. 4.18, Gm is the molar flow of solute free gas (kmol/m s), is the molar flow of solute free liquid (kmol/m s), where both and Gm remain constant throughout the column. Y is the mole ratio of solute in the gas phase (kmol of solute/kmol of solute free gas), X is the mole ratio of solute in the liquid phase (kmol of...

Miller and Hawthorne [416] have developed a chromatographic method that allows subcritical (hot/liquid) water to be used as a mobile phase for packed-column RPLC with solute detection by FID, UV or F also PHWE-LC-GC-FTD couplings are used. Before LC elution the extract is dried in a solid-phase trap to remove the water. In analogy to SFE-SFC, on-line coupled superheated water extraction-superheated water chromatography (SWE-SWC) has been proposed [417]. On-line sample extraction, clean-up and fractionation increases sensitivity, avoids contamination and minimises sources of error. 

In subsequent work, ordering in solutions of the same matched diblock and triblock spanning a broader range of volume fractions, 0.1 < < 0.4, was explored (Hamley et al. 1997). For liquid-like and SAXS showed that there was no inter-micellar order in the liquid. Above a crossover concentration 0.2, ordering of micelles was shown by the presence of a structure factor peak. The ordered micellar structure, identified as hexagonal-packed cylinders for more concentrated solutions, persisted up to an order-disorder transition located from a discontinuity in the... 

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