Surfactants greatly influence degreasing velocity. To explain the differences due to surfactant type, we analyzed the remaining oil film thickness (T) and the emulsion characteristics induced by the surfactants involved It became clear that T had a strong relationship to the average oil globule diameter r∞ in the oil emulsion, which had been formed at a low concentration. T and (dT/dt)are summarized as follows: T=r∞/R, dT/dt(initial)=-C1*ra(T-r∞)/√r∞, dT/dt(end)=-C2*√r∞.
R: Water wetting area ratio, ra: Substantial oil globule diameter of highly concentrated emulsion in boundary film. The degreasing velocity (dT/dt) in all surfactants was decided by ra and r∞ size. These sizes characteristically depended on the surfactant type and oil concentration. The ideal surfactant for high-speed degreasing, should therefore form an oil globule distribution at the smallest size<0.1 and r∞=2, ra>30μm.
Little possibility existed; however, that (dT/dt) was controllable by using the specific globule size alone, which had the slowest movement velocity, only when degreasing by the surfactant ABS, etc., had nearly been completed.
