| Autor: |
Yasuhiko Arai, Yoshio Iwai, Machiko Uno, Hirotaka Nagano, Gil Sun Lee |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
The Journal of Supercritical Fluids. 38:312-318 |
| ISSN: |
0896-8446 |
| DOI: |
10.1016/j.supflu.2005.12.005 |
| Popis: |
The solubilities of caffeine in supercritical CO 2 , supercritical CO 2 + water, supercritical CO 2 + ethanol, and supercritical CO 2 + water + ethanol were measured with a circulation-type apparatus combined with an on-line Fourier transform infrared (FT-IR) spectrometer at 313.2 K and 15.0 MPa. The solubilities of caffeine were determined with the peak absorbances of caffeine at 1190 cm −1 . The solubilities of caffeine increase until water is saturated in supercritical CO 2 . The maximum increase rate is 22%. In CO 2 + caffeine + ethanol system, the solubilities of caffeine increase with increasing the concentration of ethanol. The solubility of caffeine becomes five times when 1000 mol m −3 of ethanol is added. In CO 2 + caffeine + water + ethanol system, the solubilities of caffeine are smaller than those with single entrainer of water or ethanol. The shape of the peaks of two C O stretching bands for caffeine were changed by the addition of ethanol. It was confirmed that the interaction species of caffeine interacting with ethanol are produced by deconvolution of the C O stretching bands. The enhancement of solubility for caffeine in supercritical CO 2 by the addition of ethanol is due to the hydrogen bonding between caffeine and ethanol. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect