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Electrostatic Filter Media

The concept of electrostatically charging a filter media (often called an electret) was discovered in 1931 and has been used to enhance filter media efficiency since then.  Most modern electrostatically charged filter medias are produced from polymeric (synthetic) materials.  Many polymers will become charged during the process of converting them to fibers and filter media.  This charge is often short lived.  Fibers of different polymers can be combined in a filter media to create a “triboelectric” charge.  Again, this electrostatic charge may not last long in a filter.  Another method of creating an electrostatic filter media is by corona discharge, which creates fibers of opposite charge in cross section.  In all cases, particles of an opposite charge to the attracting filter media fiber or particles with a dipole (oppositely charged ends) are attracted to the filter media fibers in a similar way to dust being attracted to a television screen.