Pervaporation, in its simplest form, is an energy efficient combination of membrane permeation and evaporation.   It's considered an attractive alternative to other separation methods for a variety of processes.  For example, with the low temperatures and pressures involved in pervaporation, it often has cost and performance advantages for the separation of constant-boiling azeotropes.

Designing a randomly packed column is a subtle blend of art and science. Packed columns are most frequently used to remove contaminants from a gas stream (absorption). However, packed columns can also be used to remove volatile components from a liquid stream by contacting it with an inert gas (stripping). They are also used in distillation applications where the separation is particularly difficult due to close boiling components. While we'll discuss all of these applications, we'll focus on absorption. However, the design methods are similar for any of the scenarios.