In our laboratory high-intensity ultrasound (US) are employed in organic syntheses, for the degradation of persistent organic pollutants and for the extraction of organic compounds from vegetal matrices. In the present work US-assisted and conventional extraction were compared on two natural oil sources. A newly devised US reactor (18.3 kHz) considerably improved extraction rates and yields. The effect of US is mainly due to the mechanical fragmentation of plant cell walls that increases direct exposition of cell contents to the solvent. US can also facilitate the hydration and swelling of dried plant material, improving diffusion of soluble components4. For comparison we experimented with different US devices and frequencies (18.3, 20.6, 300 and 500 kHz) in the extraction of soybean germ (SG) and rice bran (RB), as shown in Table 1. Besides petroleum ether (PE), we also used as solvents several ionic liquids (ILs) (Table 2). We compared results with those obtained by conventional techniques (static extraction at room temperature and refluxing in a soxhlet). The new US device (Fig.1) we call a “cavitating tube” (18.3 kHz) uniformly gave the highest yields. Most apolar ILs proved very efficient solvents for the extraction of SG under US at 20 KHz.
EXTRACTION OF NATURAL PRODUCTS UNDER HIGH-INTENSITY ULTRASOUND: “THE CAVITATING TUBE"
BOFFA, Luisa;BINELLO, Arianna;CRAVOTTO, Giancarlo
2005-01-01
Abstract
In our laboratory high-intensity ultrasound (US) are employed in organic syntheses, for the degradation of persistent organic pollutants and for the extraction of organic compounds from vegetal matrices. In the present work US-assisted and conventional extraction were compared on two natural oil sources. A newly devised US reactor (18.3 kHz) considerably improved extraction rates and yields. The effect of US is mainly due to the mechanical fragmentation of plant cell walls that increases direct exposition of cell contents to the solvent. US can also facilitate the hydration and swelling of dried plant material, improving diffusion of soluble components4. For comparison we experimented with different US devices and frequencies (18.3, 20.6, 300 and 500 kHz) in the extraction of soybean germ (SG) and rice bran (RB), as shown in Table 1. Besides petroleum ether (PE), we also used as solvents several ionic liquids (ILs) (Table 2). We compared results with those obtained by conventional techniques (static extraction at room temperature and refluxing in a soxhlet). The new US device (Fig.1) we call a “cavitating tube” (18.3 kHz) uniformly gave the highest yields. Most apolar ILs proved very efficient solvents for the extraction of SG under US at 20 KHz.
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