The correlation of individual film coefficients of mass transfer in a stirred cell

Abstract

To assist in the interpretation of over-all mass transfer coefficients in liquid-liquid extraction in stirred cell experiments the following improved correlation has been derived on the basis of the data of Lewis: ▪ This relation has been confirmed by new experimental data obtained using a cell of slightly modified construction. Systems studied were: 1. The benzene-water- isopropyl alcohol system. 2. The benzene-water-amyl alcohol system. 3. The ethyl acetate-water system. 4. Systems (1) and (2) in the presence of polyethylene oxide in the aqueous phase to increase the viscosity. During the development of the correlation it is shown that the individual film coefficients, k 1, are not entirely independent of the diffusion coefficients, D 1, of the respective phases, so that the transfer is not completely controlled by eddy diffusivity. It was found that k 1 is proportional to D 1 with an exponent of 1 6 , which is less than the exponent of 1 2 required if the transfer takes place only by unsteady-state diffusion into stagnant surface elements, but which is nearer the exponent of zero required if the transfer takes place by a turbulent mixing process.