In wetted wall columns, pure carbon dioxide was absorbed in water containing surface active agent.
With the increase in the concentration of the agent, rippling on the surface of the liquid film decreased. When the concentration of the agent exceeded a certain value, rippling almost disappeared. The effect of this change in rippling on the rate of mass transfer from gas to liquid across the interface was studied, and the results obtained are shown in Fig. 2 and 3, in which HL is plotted versus Re on logarithmic coordinates.
From these results, it appears that with the decrease in rippling, the disturbance caused by the mixing action of ripples decreases and the flow pattern of the liquid film in the pseudo-stream line flow approaches that of the liquid film in the true viscous flow.
The results obtained by the present author and the previous investigators^{3, 6)} for the case when there was no rippling, are shown in Figs. 5 and 6, respectively, as the plots of HL/z versus l/p on logarithmic coordinates. The best line through the data can be expressed by Eq. (8). This experimental line lies above the theoretical line based on the unsteady-state diffusion theory derived by Pigford⁹. The discrepancy between the theory and the experiment is probably due to the difference between the assumed and actual flow conditions for the liquid film.