Molecular distillation is a distillation method operated under high
vacuum, where the average free path of the vapor molecules is
greater than the distance between the evaporating surface and the
condensing surface.Thus, the liquid mixture can be separated by the
difference of evaporation rate of each component in the feed
liquid.
At a given temperature, the lower the pressure, the greater the
average free path of the gas molecules.When the pressure in the
evaporation space is very low (10-2 ~ 10-4 mmHg) and the
condensation surface is close to the evaporation surface, and the
vertical distance between them is less than the average free path
of the gas molecules, the vapor molecules vaporized from the
evaporation surface can directly reach the condensation surface
without colliding with other molecules and condense.
