Multiphase extraction process

Before leaving ionic liquids it is worth mentioning their potential value in separation processes. Organic solvents are frequently used in multiphase extraction processes and pose the same problems in terms of VOC containment and recovery as they do in syntheses, hence ionic liquids could offer a more benign alternative. Interesting applications along this line which have been studied include separation of spent nuclear fuel from other nuclear waste and extraction of the antibiotic erythromycin-A. 

In a supercritical extraction process a solvent is contacted with a solute at conditions near a critical point of the solvent plus solute mixture. The mixture may exhibit multiphase behavior invoving vapor, liquid, and solid phases, depending on the mixture composition and temperature and pressure conditions. 

The results obtained with the reported extraction model showed that the separation of charged species is possible, provided a suitable ligand hydrophobicity. Further analytical developments of these multiphase extraction systems will require an accurate investigation of the equilibria and kinetic processes occurring at the interfaces, as well as the study of the micellar structure and properties of the host aggregates. 

SPME is a multiphase equilibration process. Analytes, from the matrix in which the fibre is exposed to, will be transported into the coating of the SPME fibre as soon as the fibre is exposed. The extraction time can be considered complete when the analyte concentration has reached equilibrium between the sample matrix and the fibre coating. When using this in experimental conditions, it means that when the equilibrium is reached the... 

Interestingly, in multiphase catalytic processes the primary products can be extracted during the reaction thus modulating the product selectivity (using different substrates and reaction products solubility with the catalyst containing phase, such as dienes/monoenes and arenes/cycloalkenes). Indeed, this approach can constitute a suitable method for avoiding consecutive reactions of primary products and has been used in the partial hydrogenation of dienes and arenes by transition-metal NPs dispersed in ILs. 

In addition to the enzymatic fat splitting and esterifications, a multiphase extractive enzyme membrane reactor is being used for the industrial production of a diltiazem chiral intermediate. This process will be described in more detail in Section 5.3.5. 

SPME is a multiphase equilibration process. Frequently, the extraction system is complex, as in a sample consisting of an aqueous phase with suspended solid particles having various adsorption interactions with analytes, plus a gaseous headspace. In some cases, specific factors have to be considered. 

Flowever, information concerning the characteristics of these systems under the conditions of a continuous process is still very limited. From a practical point of view, the concept of ionic liquid multiphasic catalysis can be applicable only if the resultant catalytic lifetimes and the elution losses of catalytic components into the organic or extractant layer containing products are within commercially acceptable ranges. To illustrate these points, two examples of applications mn on continuous pilot operation are described (i) biphasic dimerization of olefins catalyzed by nickel complexes in chloroaluminates, and (ii) biphasic alkylation of aromatic hydrocarbons with olefins and light olefin alkylation with isobutane, catalyzed by acidic chloroaluminates. 

Figure 4.21 Multiphase membrane reactor synthesis of ibuprofen from ibuprofen methoxyethyl ester applying a multiphase membrane reactor in batch mode followed by extraction and distillation for downstream processing...

To test the effectiveness of the CHEMFIX process as a treatment option, the solidified samples were subjected to the TCLP test and a comparison made with the TCLP results on a raw sample. This test was designed to determine the mobility of contaminants present in liquid, solid and multiphasic wastes. If the TCLP extract from a representative sample contained any of the listed contaminants above the regulatory levels it would be considered a hazardous waste and should adhere to the strict disposal requirements. )... 

The rest of this chapter is a discussion of selected examples of equipment used to study the kinetics of multiphase reactions. We begin with instrumentation suitable for industrial process development in the fine chemicals area and then move on to more sophisticated methods which can be used to extract true surface kinetics data even in the presence of sharp concentration gradients near the surface. 

Reactive absorption, reactive distillation, and reactive extraction occur in multicomponent multiphase fluid systems, and thus a single modeling framework for these processes is desirable. In this respect, different possible ways to build such a framework are discussed, and it is advocated that the rate-based approach provides the most rigorous and appropriate way. By this approach, direct consideration... 

Extraction is a mass exchange process in a multiphase and multicomponent system that involves transfer and distribution of one or more components into two... 

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