Pervaporation can be used to dehydrate solvents without the use of any third substance. Azeotropes can simply be split, irrespective of vapour-liquid equilibrium conditions and at low cost. In the same way, methanol can be removed from other organic solvents. A vacuum driving force is applied to the back side of the membranes, allowing almost complete removal of the permeating component (vapour). The feed to the membranes can either be in the liquid (pervaporation) or vapour phase (vapour permeation). Separation is predominantly affected by differences in polarity. The process features of pervaporation are tailor-made membranes which selectively remove one or more components, flexible operation – a single unit can be designed to treat a large number of solvents with different component feed concentrations, flexibility for batch or continuous operation depending on the solvent properties and energy costs, possibility of process intensification via hybrid operation with distillation and standard skid mounted units.