TY - JOUR
T1 - Measurement of entrainer effects of water and ethanol on solubility of caffeine in supercritical carbon dioxide by FT-IR spectroscopy
AU - Iwai, Yoshio
AU - Nagano, Hirotaka
AU - Lee, Gil Sun
AU - Uno, Machiko
AU - Arai, Yasuhiko
N1 - Funding Information:
The authors gratefully acknowledge the financial support provided by a Grant-in-Aid for the 21st century center of excellent (COE) program, “Functional Innovation of Molecular Informatics”, and for Scientific research (C), 16560660, 2004, from the Ministry of Education, Science, Sports and Culture of Japan.
PY - 2006/10
Y1 - 2006/10
N2 - The solubilities of caffeine in supercritical CO2, supercritical CO2 + water, supercritical CO2 + ethanol, and supercritical CO2 + 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 CO2. The maximum increase rate is 22%. In CO2 + 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 CO2 + 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{double bond, long}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{double bond, long}O stretching bands. The enhancement of solubility for caffeine in supercritical CO2 by the addition of ethanol is due to the hydrogen bonding between caffeine and ethanol.
AB - The solubilities of caffeine in supercritical CO2, supercritical CO2 + water, supercritical CO2 + ethanol, and supercritical CO2 + 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 CO2. The maximum increase rate is 22%. In CO2 + 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 CO2 + 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{double bond, long}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{double bond, long}O stretching bands. The enhancement of solubility for caffeine in supercritical CO2 by the addition of ethanol is due to the hydrogen bonding between caffeine and ethanol.
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U2 - 10.1016/j.supflu.2005.12.005
DO - 10.1016/j.supflu.2005.12.005
M3 - Article
AN - SCOPUS:33749449269
SN - 0896-8446
VL - 38
SP - 312
EP - 318
JO - Journal of Supercritical Fluids
JF - Journal of Supercritical Fluids
IS - 3
ER -