Extraction practical

McHugh MA and Krukonis VJ. 1994. Supercritical Fluid Extraction Practice and Principles, 2nd ed. Boston Butterworth-Heinemann, pp. 14-16. 

For the two-component, two-phase liquid system, the question arises as to how much of each of the pure liquid components dissolves in the other at equilibrium. Indeed, some pairs of liquids are so soluble in each other that they become completely miscible with each other when mixed at any proportions. Such pairs, for example, are water and 1-propanol or benzene and carbon tetrachloride. Other pairs of liquids are practically insoluble in each other, as, for example, water and carbon tetrachloride. Finally, there are pairs of liquids that are completely miscible at certain temperatures, but not at others. For example, water and triethylamine are miscible below 18°C, but not above. Such pairs of liquids are said to have a critical solution temperature, For some pairs of liquids, there is a lower (LOST), as in the water-tiiethylamine pair, but the more common behavior is for pairs of liquids to have an upper (UCST), (Fig. 2.2) and some may even have a closed mutual solubility loop [3]. Such instances are rare in solvent extraction practice, but have been exploited in some systems, where separations have been affected by changes in the temperature. 

General solvent extraction practice involves only systems that are unsaturated relative to the solute(s). In such a ternary system, there would be two almost immiscible liquid phases (one that is generally aqueous) and a solute at a relatively low concentration that is distributed between them. The single degree of freedom available in such instances (at a given temperature) can be construed as the free choice of the concentration of the solute in one of the phases, provided it is below the saturation value (i.e., its solubility in that phase). Its concentration in the other phase is fixed by the equilibrium condition. The question arises of whether or not its distribution between the two liquid phases can be predicted. 

One boundary condition for Eq. (29) is p = p0 for x -> oo. The second boundary condition can be taken as p = 0 for x = Lsc, which is true for a very fast electrode reaction that extracts practically all the holes from the space-charge region. Solving Eq. (29) with these boundary conditions and then calculating the diffusion current of holes from the bulk into the space-charge region at x = Lsc, we obtain... 

Introduction of the expander, a high-shear extruder with an interrupted-flight screw, in the mid-1980s revolutionized oilseed extraction practices. Essentially all solvent-extracted cottonseed, and approximately 70 percent of domestic soybean tonnage now are processed... 

Nitric acid is without action on pure platinum, and the hot concentrated acid should extract practically nothing from a well-cleaned crucible of the pure metal.3... 

The values for the crude oil compare closely with those of other commercial oils, such as soybean oil, when produced according to good extraction practices. Chlorophylls and sulfur compounds levels are higher in canola oil compared with most other commodity oils. The deodorized oil data reflect good refining practice and are similar to the data obtained with other deodorized commodity oils processed for food applications. 

The countercurrent model as shown here is not practical for real-world separations because the material losses sustained from five phase separation steps would make the real recovery closer to 50% than the predicted 75%. To make countercurrent extractions practical, they must be implemented in a flow stream, cartridge, or other geometry, where material losses are not so devastating. One such approach is given below. 

The colour reaction is carried out in 0.1 M HCl, and the time necessary for colour development in the aqueous pseudo-solution is 50 min. In the extractive spectrophotometric method [36], the time for reaction at pH 2-3 (in the presence of formic acid) is 30 min, after which the solution is neutralized to pH 6-7, and the piazselenol is extracted into toluene. The colour reaction may be accelerated by heating the solution. Within the pH range 5-10, the distribution coefficient of piazselenol between toluene and water is high, and one portion of toluene extracts practically all the selenium complex into the organic phase. The free reagent (DAB) is also extracted. Related solvents such as benzene and xylene may be substituted for toluene. 

The next step in purification is separation of uranyl nitrate from the other metallic impurities in the dissolver solution by solvent extraction. Practically aU uranium refineries now use as solvent tributyl phosphate (TBP) dissolved in an inert hydrocarbon diluent. The first U.S. refinery used diethyl ether as solvent and later refineries have used methyl isobutyl ketone or organic amines, but practically all have now adopted TBP. It is nonvolatile, chemically stable, selective for uranium, and has a uranium distribution coefficient greater than unity when the aqueous phase contains nitric acid or inorganic nitrates. 

Woerfel, J.B. Extraction. Practical Handbook of Soybean Processing and Utilization, Second ed. D.R. Erickson, Ed. AOCS Press Champaign, IL, 1995 pp. 65-92. 

The versatility of ISEs was enhanced considerably by the introduction of membranes containing neutral ion carriers (ionophores). The first ISE of this type, with a membrane containing valinomycin and selective for potassium ions, was described by Stefanac and Simon in 1966. There are many liquid chemical systems that interact highly selectively with ions through, e.g., ion exchange, ion association, or solvent extraction. Practically useful ISEs based on these systems and on neutral ionophores have been obtained due to the gradual perfection of the technology of plasticized poly(vinyl chloride) (PVC) matrix membranes. 

Efficiency of Multiple Extractions PRACTICE OF LIQUID-LIQUID EXTRACTION... 

Aoki, K., Ogata, Y, and Shibata, D. 2007. Approaches for extracting practical information from gene co-expression networks in plant biology. Plant Cell Physiol 48 381-390. 

As the glycerol can be extracted practically pure, it should be possible to use the chemical method of estimation given under Glycerin. 

The introduction of the expander, a high-shear extruder with cut-flight screw, revolutionized oilseed extraction practices in the latter half of the 1980s. By 1990, over 80 percent of the soybean and cottonseed tonnage processed domestically used this technique. The expander heats, homogenizes, and shapes... 

The partition oQefflclents obtained by Keder, et for the extraction of actinide metals from nitric acid solutionsby 10 volume percent TrtOA In xylene are given In figure 52. Carswell has studied the extraction of uranium and thorlxim by 0.2H TnOA in toluene, also, from nitric acid solution. Thorium appears to be more strongly extracted than uranium In the latter system. Ocanlum, however, is extracted practically to the same extent In both systems for acid concentrations up to 6m. 

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