Ultrasound in gas-liquid systems: effects on solubility and mass transfer.
The effect of ultrasound on the pseudo-solubility of nitrogen in water and on gas-liquid mass transfer kinetics has been investigated in an autoclave reactor equipped with a gas induced impeller. In order to use organic liquids and to investigate the effect of pressure, gas-liquid mass transfer coefficient was calculated from the evolution of autoclave pressure during gas absorption to avoid any side-effects of ultrasound on the concentrations measurements. Ultrasound effect on the apparent solubility is very low (below 12%). Conversely ultrasound greatly improves gas-liquid mass transfer, especially below gas induction speed, this improvement being boosted by pressure. In typical conditions of organic synthesis: 323 K, 1100 rpm, 10 bar, k(L).a is multiplied by 11 with ultrasound (20 kHz/62.6 W). The impact of sonication is much higher on gassing out than on gassing in. In the same conditions, this enhancement is at least five times higher for degassing.
Laugier
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Laboratoire de Génie Chimique, 5 rue Paulin Talabot, BP 1301, 31 106 Toulouse, France.
Andriantsiferana
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Wilhelm
A M
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Delmas
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D000465:Algorithms; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005740:Gases / Q000737:chemistry* / Q000528:radiation effects*; D007700:Kinetics; D011312:Pressure; D012995:Solubility; D013696:Temperature; D014465:Ultrasonics
D005740:Gases