Solvent Extraction by a Rising Slug

Abstract

<p> Several types of apparatus have been previously developed to give a constant and measurable interfacial area for solvent extraction. In this work, a new and relatively simple device for this purpose has been tested. The organic phase is allowed to rise or fall freely through the aqueous phase in a tube as a cylindrical "slug". In the mass transfer operation, the "slug" of sparingly-soluble organic liquid is held stationary by the downflow of water. The shrinkage rate of the slug can be measured easily and it gives the experimental mass transfer rate. In order to apply the Higbie penetration theory to the experimental conditions, the interfacial velocity and radius ratio of the slug must be known; these factors can be calculated from the hydrodynamics of the system, using the measured value of slug superficial velocity. Finally, a comparison between experimental and theoretical mass transfer results can be made. 1-butanol shows a good agreement (to within 1%) while 1-pentanol and methyl iso-butyl ketone show less satisfactory agreement due to lack of precise data on their molecular diffusivities in water.</p>