Multicomponent extraction example

This example considers the interactions involved in multicomponent extraction as shown in Sec. 3.3.1.2 and takes the particular case of a single batch extractor with two interacting solutes. 

All these methods give similar results but their sensitivities and resolutions are different. For example, UV-Vis spectrophotometry gives good results if a single colorant or mixture of colorants (with different absorption spectra) were previously separated by SPE, ion pair formation, and a good previous extraction. Due to their added-value capability, HPLC and CE became the ideal techniques for the analysis of multicomponent mixtures of natural and synthetic colorants found in drinks. To make correct evaluations in complex dye mixtures, a chemometric multicomponent analysis (PLS, nonlinear regression) is necessary to discriminate colorant contributions from other food constituents (sugars, phenolics, etc.). 

Equilibrium data correlations can be extremely complex, especially when related to non-ideal multicomponent mixtures, and in order to handle such real life complex simulations, a commercial dynamic simulator with access to a physical property data-base often becomes essential. The approach in this text, is based, however, on the basic concepts of ideal behaviour, as expressed by Henry s law for gas absorption, the use of constant relative volatility values for distillation and constant distribution coeficients for solvent extraction. These have the advantage that they normally enable an explicit method of solution and avoid the more cumbersome iterative types of procedure, which would otherwise be required. Simulation examples in which more complex forms of equilibria are employed are STEAM and BUBBLE. 

The most common method of isolation and sample cleanup involves contacting a filtered aqueous solution with an appropriate immiscible organic solvent in a. aboratory separatory funnel of appropriate size. Some specific examples are discussed later. With multicomponent samples a single solvent or solvent mixture is unlikely to extract all components equally causing discrimination. Ihis discrimination may be useful if the solvent discriminates against the extraction of solutes that are not of interest in the analysis. 

In addition to the applications in extractive distillation referred to above, there are other industrial examples where electrolytes in mixed solvents occur. In many industrial situations nonvolatile electrolytes are either added to effect the separation of multicomponent process streams (e.g., the complexing agents added to enhance distribution coefficients in solvent extraction) or are present as a result of the process itself. Ex-... 

It is not known whether high-pressure fluids are Newtonian fluids that behave according to the laws given by Eqns. (3.4-1), (3.4-2), and (3.4-3). With regards to diffusion problems, for example, the Fickian nature of diffusion may be rather the exception than the rule. The diffusivity often depends on solute concentration, not only in extraction with a supercritical gas [1] but also in ordinary low-pressure diffusion in the gas phase and in diffusion in a liquid in multicomponent systems and in porous media. 

Originally, extractive distillation was limited to two-component problems. However, recent developments in solvent technology enabled applications of this hybrid separation in multicomponent systems as well. An example of such application is the BTX process of the GTC Technology Corp., shown in Figure 6, in which extractive distillation replaced the conventional liquid-liquid extraction to separate aromatics from catalytic reformate or pyrolysis gasoline. This led to a ca. 25% lower capital cost and a ca. 15% decrease in energy consumption (170). Some other examples of existing and potential applications of the extractive distillations are listed in Table 6. 

In this case study, which is extracted from reference 184, infrared dichroism is described as a means of separating the component dynamics in multicomponent polymer melts. What is necessary is the existence of distinct absorption peaks for at least one of the components. In the present problem, however, where two chains of identical chemistry but different molecular weights are mixed, there will not be any intrinsic differences in their absorption spectra. In this case it is necessary to label one of chains with a tag that will allow its presence in the blend to be revealed. For this purpose, deuteration of one of the chains is often used. This provides the labeled chain with an absorption of infrared light at the symmetric stretching vibration of the C-D bond, which occurs in the vicinity of 2180 cm-1. Fortunately, the unlabeled polymer contains no absorption peak at this location. It is important, however, to determine that the presence of a label on one species will not alter the physical response of the sample at a level that will affect the phenomena under study. For example, the labeling should not induce phase separation or cause unwanted specific interactions. 

In comparing separation techniques, we generally find a striking difference in methods based on continuous (c) chemical potential profiles and those involving discontinuous (d or cd) profiles. There is, for example, a glaring contrast in instrumentation, applications, experimental techniques, and the capability for multicomponent separations between the two basic static systems, Sc (e.g., electrophoresis) and Sd (e.g., extraction). Similarly, there... 

In mass transfer apparatus one of two processes can take place. Multicomponent mixtures can either be separated into their individual substances or in reverse can be produced from these individual components. This happens in mass transfer apparatus by bringing the components into contact with each other and using the different solubilities of the individual components in the phases to separate or bind them together. An example, which we have already discussed, was the transfer of a component from a liquid mixture into a gas by evaporation. In the following section we will limit ourselves to mass transfer devices in which physical processes take place. Apparatus where a chemical reaction also influences the mass transfer will be discussed in section 2.5. Mass will be transferred between two phases which are in direct contact with each other and are not separated by a membrane which is only permeable for certain components. The individual phases will mostly flow countercurrent to each other, in order to get the best mass transfer. The separation processes most frequently implemented are absorption, extraction and rectification. 

Another type of foam has been observed when a multicomponent liquid has a composition close to a separation into two liquid phases. Surface tension drops to a very low value, allowing easy formation of bubbles. An example is found in solvent recovery from lubricating-oil extraction processes. This type of foam has been referred to as Ross foam,f ° named after an investigator of these foams. 

Example 6,6.1 Multicomponent Diffusion in a Batch Extraction Cell... 

Ideal reactions for solution-phase parallel synthesis are those that are kinetically and thermodynamically favored, are tolerant of diverse functionality, and have a broad range of reactant tolerance. In this approach, capture resins and extraction procedures are often used for preliminary purification. The solution-phase reaction conditions must be validated in terms of scope and optimal reaction conditions over the range of reactants. Two common strategies for solution libraries involve derivatization of preformed functionalized scaffolds and multicomponent condensation reactions, for example, the Ugi reaction, the Passerini reaction, and the formation of hydroxyamininimides from an ester, a hydrazine, and an epoxide. 

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