Semi-permeable membranes - General

Artificial semi-permeable (or selectively permeable or permselective) membranes are gradually being used by a wide variety of industries in an ever-increasing number of fields.

This universal use, especially for fine separations, requires knowledge of membrane performance. The two most important properties of a membrane are permeability and selectivity. However, in view of the original way in which material transport or energy transfer through the membrane material is effected or prevented, performance data can currently only be provided for specific conditions of use. With a few exceptions, there are no standardized methods for determining performance.

As a result, the numerical values given in the tables are those provided by the diaphragm manufacturer, with the aim of achieving a degree of harmonization which should encourage universal presentation of performance. This is why, in all the articles in this section and wherever possible, only the units of the international system and their symbols have been used.