Evaporation Retarded by Monolayers

Abstract

The reduction in the steady-state rate of evaporation of water by hexadecanol monolayers depends only on the air velocity above the surface and is independent of the absolute rate of evaporation up to air velocities of 40 centimeters per second. This indicates that the monolayer does not affect the vaporization step but increases the size of the diffusion boundary layer. The mechanism (the creation of a surface pressure gradient in the monolayer which reduces the net stress on the surface by the air) is discussed.