Extraction comparison with distillation

Ehlers, D., Kirchhoff, J., Gerard, D. and Quirin, K.W. (1 998) High performance liquid chromatography analysis of nutmeg and mace oils produced by supercritical C02 extraction - comparison with steam distilled oils, comparison of East Indian, West Indian and Papuan oils. International Journal of Food Science and Technology 33(3), 215-223. 

In comparison with distillation, the most widely used process, knowledge of the fundamentals of Uquid/liquid extraction is limited. A sufficiently accurate description of the hydrodynamics and mass-transfer rates of liquid systems for the design of apparatus is currently not possible for many practical applications.The development of an extraction apparatus generally requires cost-intensive and timepilot plants. Tests with original solutions, for example, from an integrated miniplant, are especially important here (see Section 4.5). 

Optimization. Optimi2ation of the design variables is an important yet often neglected step in the design of extractive distillation sequences. The cost of the solvent recovery (qv) step affects the optimi2ation and thus must also be included. Optimi2ation not only yields the most efficient extractive distillation design, it is also a prerequisite for vaUd comparisons with other separation sequences and methods. 

Acetic acid is an important intermediate organic tonnage chemical that may be produced by the petroleum industry and fermentation. The latter process requires the recovery of acetic acid from water solutions, and several techniques have been applied to this separation, including solvent extraction, azeotropic distillation, and extractive distillation. A comparison of economics between azeotropic distillation and solvent extraction combined with azeotropic distillation (Table 10.3) shows that the introduction of... 

The reaction is carried out under a dry nitrogen atmosphere. To a mixture of 7.32 g (40 mmol) of ( )-bromophenylethcnc and 0.20 mmol of the palladium complex are added 100 mL (80 mmol) of a 0.8 M solution of [a-(trimethylsilyl)benzyl]magnesium bromide in diethyl ether at —78 °C. The mixture is allowed to warm and stirred at 0 "C for 2 d and then hydrolyzed with 10% HCI at 0 C. The organic layer and ether extracts from the aqueous layer are combined, washed with aq NaHCG3 and then water, and dried over anhyd MgS04. The solvent is evaporated and the product isolated by distillation yield 10.1 g (93% ) bp 135-139 JC/0.9 Torr [a]p° —43.9 (c = 1.0, benzene) 95% op (determined by hydrogenation and direct comparison with an authentic sample prepared via asymmetric hydrosilylation and correlated with 1,3-diphenyl-t -propanol). 

Lucchesi, M.E., F. Chemat, and J. Smadja. 2004. Solvent-free microwave extraction of essentials oil from aromatic herbs Comparison with conventional hydro-distillation. J. Chromatogr. A 1043 323-327. 

Table V. Comparison of the Amount of Oxidizable Material Extracted with Distilled Water and With Tap Water...

Tiemann studied the further oxidation of D-gluconic acid with bromine at 100 a reducing sirup was formed which was isolated as an amorphous barium salt or a crystalline osazone. Ruff repeated the work and could find no oxygluconic acid in the oxidation mixture most of the D-gluconic acid was unaltered and the reducing power was very low, especially in comparison with that obtained when keto aldonic acids were prepared by the action of hydrogen peroxide and ferrous salts. By ether extraction and distillation the formation of formic, oxalic and glycolic acids was shown. 

Steam distillation (30 min) corresponds with good manufacturing practice (GMP) in the processing of lavender oil and is without any influence on the genuine chirality of linalool, as to conclude by comparison with the results on linalool enantiomeric ratio from the diethyl ether extraction. 

L. Liang, M. Horvat, X.B. Feng et al.. Reevaluation of Distillation and Comparison with FINO3 Leaching/Solvent Extraction for Isolation of Methylmercury Compounds from Sediment/Soil Samples, Appl. Organo-metal. Chem. 18(6), 264-270, June (2004). 

Identified by Viani et al. (1965), the structure was confirmed by IR-spectroscopy comparison with a commercially available sample found also by Gianturco et al. (1966), Stoffelsma et al. (1968) and by Silwar et al. (1987) in the analysis of a coffee-aroma extract obtained by distillation-extraction and concentration (2.0 5.0 ppm in coffee). Procida et al. (1987) detected this ketoester in a roasted arabica but in none of the green coffees that they studied. Ramos et al. (1998) found it in a brew only after liquid-liquid extraction with pentane or methylene chloride. 

Identified in an aroma complex of roasted coffee by Bondarovich et al. (1967) and a little later by Stoffelsma and Pypker (1968) and Stoffelsma et al. (1968), after steam distillation, fractionation and preparative GC for identification by IR spectroscopy, and comparison with authentic samples. Silwar et al. (1987) estimated its concentration at 2.0-3.0ppm (see F.19), and Ho et al. (1993) at 4.58ppm in a roasted Columbian coffee. The latter authors identified only two purely aliphatic esters in their analysis (see F.24). Ramos et al. (1998) identified it in a brewed arabica only after liquid-liquid extraction with methylene chloride (compare with F.8). 

Since the work of Chfford et al., several studies of the small-scale extraction of essential components have been made and the work and methods have been reviewed [62-64]. Work has been carried out on eucalyptus [65] peppermint [66, 67], savory [67], laurel [68] and Thymbria spicata [69]. These reach similar conclusions to those made above for rosemary, wild marjoram and clove and in some cases comparisons with steam distillation and other methods have been made [58, 60, 61, 66, 68]. In addition to essential oil components, work is also being carried out on the extraction of compounds for analytical purposes [70, 71], including the extraction of metals [72, 73]. Other extractions of medical and industrial interest are being car-... 

When the available models for SFE are compared with distillation and liquid-liquid extraction models, it becomes apparent that the existing models for SFE still need considerable further development. The reasons for this unfavorable comparison may be stated as. Phase behavior of the systems handled by distillation and liquid-liquid extraction, is better understood since they frequently deal with a smaller number, and better defined, components, whereas in the natural materials extraction a basically solid natured host matrix, which hard to define precisely, is to be dealt with. Furthermore, in most instances the number of species involved in the extracts is very high and tliey are not as well defined with respect to their physicochemical properties. 

Finally, it is also interesting to report that in the literature it is possible to find studies dealing with esterification membrane reactor units coupled with other than distillation-based separation technologies. An example is the work of Park and Tsotsis (2004), who linked to the permeate side of the membrane reactor an adsorption step to increase byproduct extraction. Adsorption is a very powerful technology and leads to higher conversion in comparison with a conventional reactor (up to 10%). However, the cost of the adsorbent and of related equipment makes this design economically disadvantageous. 

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