The dissolution rate of a pipe wall into a falling liquid film was measured. Systems employed for this study were iron in dilute sulfuric acid (0.01N) and zinc in aqueous iodine-potassium iodide solution (0.01N).
On the assumption that the diffusion of oxygen or iodine from the bulk of liquid to the wall surface was the controlling mechanism, the height of a liquid phase transfer unit, HL, was calculated and the result was compared with the one obtained from the theoretical equation, which the author had derived, supposing the existence of an unsteady-state diffusion and parabolic velocity distribution in the liquid film. The observed values of HL were in good agreement with the values obtained by means of the theoretical equation, as shown in Figs. 3-6.
From these results, it appears that the liquid film is formed in the viscous flow even though ripples are present at the gas-liquid interface and that the turbulence caused by the ripples remains within the thin layer near the interface.