Study of mass transfer and determination of drop size distribution in a pulsed extraction column

• Published in: Chemical engineering research & design Vol. 89; no. 1; pp. 60 - 68
• Main Authors: Ousmane, Syll, Isabelle, Mabille, Mario, Moscosa-Santillan, Mamadou, Traore, Jacques, Amouroux
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 2011; Elsevier
• Subjects: Applied sciences; Chemical engineering; Correlation; Discontinuous phase hold up; Drop size; Drop size distribution; Droplets; Exact sciences and technology; Heat and mass transfer. Packings, plates; Hold up; Image analysis; Indexing in process; Liquid-liquid extraction; Mass transfer; On-line systems; Online; Pulsed extraction column; Sauter diameter ( d32); Drop size distribution; Sauter diameter ( d32); Discontinuous phase hold up; Pulsed extraction column; Correlation; Mixing; Interface properties; Holdup; Emulsion; Dispersed phase; Liquid liquid extraction; Process control; Stirring; Extraction column; Contact angle; Droplet; Continuous phase; Adhesion; Mass transfer; Sauter diameter (d32); Drop; Image analysis; Particle size distribution; Correlation analysis; Surface tension; Energy transfer
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2010.04.011

A better understanding of pulsed liquid–liquid extraction columns was obtained by using an online digital image analysis system to characterize emulsion drop. The mass transfer of acetic acid from dispersed phase (ethyl acetate) to continuous phase (water) was studied under standard conditions. The system enabled drop size distribution (DSD) to be measured as a function of physical and thermodynamic parameters. The surface tension was investigated by static contact angle measurement. Mass transfer and energy transfer, characterized by the surface/volume ratio of the droplets were compared with the working parameters in order to interpret restrictive phenomena such as hold up and column efficiency. The experimental values of Sauter diameter ( d 32) and those predicted by a correlation proposed in the literature are in good agreement. However, the adhesion work between liquid and PTFE plate surface indicates that interface property variations, as a function of solute concentration, must be taken into account in the theoretical correlations. It was found that hold up and separation efficiency depend mainly on the stirring rate. These results show that online image analysis can be used as a process control of a liquid–liquid extraction column in order to optimize the mixing phenomena and the DSD, the key parameter of extraction efficiency.