Editing Polyimide (section)

=== Filters ===
In coal-fired power plants, waste incinerators, or cement plants, polyimide fibres are used to filter hot gases. In this application, a polyimide needle felt separates dust and particulate matter from the [[exhaust gas]].

Polyimide is also the most common material used for the reverse osmotic film in purification of water, or the concentration of dilute materials from water, such as maple syrup production.<ref>[http://www.wisegeek.net/what-is-a-reverse-osmosis-water-softener.htm What is a reverse osmosis water softener?] wisegeek.net</ref><ref>Shuey, Harry F. and Wan, Wankei (22 December 1983) {{US Patent|4532041}} Asymmetric polyimide reverse osmosis membrane, method for preparation of same and use thereof for organic liquid separations.</ref>