Coupling fluid ethanol

Indeed, the most novel approach to decaffeinate green coffee beans, which has attained industrial application, is supercritical fluid extraction (SFE) using carbon dioxide CO Supercritical CO2 is selective for the extraction of caffeine, there is no associated waste treatment of a toxic solvent and extraction times are moderate. Moreover, supercritical CO2 coupled with ethanol or water was investigated to extract caffeine Ifom green tea leaves. 

The theory was based on a simple physical model which treats the quartz as a lossless elastic solid, and the liquid as purely viscous fluid. The frequency shifts arise from coupling the oscillation of the crystal, a standing shear wave with a damped propagating shear wave in the liquid. The accuracy of this model was demonstrated using aqueous solutions of glucose and ethanol at various concentrations. 

Previous reports 30, 31) have appeared on the use of siqiercritical fluid extraction (SFE) coupled with siqrercritical fluid fractionation (SFF) for the enrichment of these FPE. Carbon dioxide (CO2) and ethanol (EtOH), as a cosolvent, were utilized to fiactionate and eruich the FPE from 1.2S to 14.5 wt% in com bran oil employing a sorbent bed. However, this prior research was performed on an analytical scale. In the present study, SFF technology of com bran oil has been sc ed up using SFE/supercritical fluid chromatogr hy (SFE/SFC). The oil is remov from the com bran 1 utilizing supercritic carbon dioxide (SC-CO2), and then the extract is fiactionated by on-line SFC to obtain a fraction enriched in FPE. 

Aliphatic alcohols are easily separated by liquid chromatography (LC) using a reversed-phase column. Unfortunately, LC does not have adequate sensitivity to alcohols, and its application to analysis of ethanol in body fluids has been hindered. Davis et al. developed a liquid chromatographic method coupled with an enzymatic method that generated NADH in a precolumn ADH-catalyzed oxidation of ethanol. Since this method is not selective for ethanol, it has only limited value for determining ethanol in body fluids. 

The density of SCF is a function of pressure and temperature. The solvent power can be varied and this can be used for coupling of a reaction with an integrated separation. The first scientists who tried this method were Doddema et al. [91]. They investigated the transesterification of nonanol with ethyl acetate. At the outlet of the reactor they reduced pressure and the solutes separated. Ethyl acetate and ethanol were extracted from the fluid in a column with SCCO2 (7.5 MPa/60 C). In a following step fresh ethyl acetate was added to the remaining mixture then it was pumped into a second enzyme reactor with SCCO2 (20 MPa/60°C). The authors achieved a conversion of over 90% for nonanol, since removal of ethanol avoided a product inhibition. 

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