Pervaporation is effective for dilute solutions containing trace or minor amounts of the component to be removed.
[2] Examples include solvent dehydration: dehydrating the ethanol/water and isopropanol/water azeotropes, continuous ethanol removal from yeast fermentors, continuous water removal from condensation reactions such as esterifications to enhance conversion and rate of the reaction, membrane introduction mass spectrometry, removing organic solvents from industrial waste waters, combination of distillation and pervaporation/vapour permeation, and concentration of hydrophobic flavour compounds in aqueous solutions (using hydrophobic membranes).
The commercially most successful pervaporation membrane system to date is based on polyvinyl alcohol.
The pores must be large enough to let water molecules pass through and retain any other solvents that have a larger molecular size such as ethanol.
The most widely available member of this class of membranes is that based on zeolite A. Alternatively to these crystalline materials, the porous structure of amorphous silica layers can be tailored towards molecular selectivity.
Very recently a break-through in hydrothermal stability has been achieved through the development of an organic-inorganic hybrid material.