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High-pressure phase behaviour of nicotine / carbon dioxide system

Research output: Contribution to conference - Without ISBN/ISSN Abstract

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Publication date2008
Original languageEnglish

Abstract

Tobacco products are composed of a great variety of constituents. Nicotine, 1-methyl-2(3-pyridyl) pyrrolidine, is a highly toxic major alkaloid found in tobacco plants and plays an important etiological role in the development of human carcinogenesis. Nicotine is also accused of the addictive potential of smoking, being classified by the Drug Abuse Advisory Committee as an addictive substance. Carbon dioxide has been extensively used for the removal of nicotine from tobacco leaves in the production of new cigarettes with reduced nicotine content. Although detailed knowledge of phase behaviour is most important for the design of any separation process, solubility of nicotine in sub/supercritical CO2 seems to have been scarcely studied. Reported measurements are restricted to the temperatures of 313 and 343 K, and covering a range of pressures of 0.9 – 8 MPa and 0.9 – 16 MPa, respectively.
In this work we present a phase behaviour study of the CO2-nicotine binary system at 313.1 K, in a pressure range of 6 to 9 MPa. The phase equilibrium measurements were performed using an apparatus that employs a high-pressure sapphire cell and allows sampling of both vapour and liquid phases. From the experimental work, it could be concluded that, according to the Scott and Van Konynenburg classification of fluid phase equilibria, the system nicotine + CO2 most likely shows type-V fluid phase behaviour. The characteristic of this type of phase behaviour is a three-phase (VLL) equilibrium, with a discontinuous critical curve. As expected, the mutual miscibility increases with increasing pressure and the mixture will be homogeneous above the upper critical pressures. These data may help in further studies on sub/supercritical CO2 extraction of nicotine from nicotine-containing products.