Coalescing filtration is a widely used technique in industry to remove oil from compressed air to achieve air quality suitable for production processes. Typically, filters are made from glass fiber nonwovens and represent heterogeneous media with complex permeability and capillary properties defined by fiber dimensions and media density. An important parameter for the overall filter efficiency is the saturation of the filter media and the formation of the oil film. The resulting pressure drop significantly increases the energy cost of the process.

Currently, a well-established technology is to reduce the surface energy of the fiber surface using fluorine-based formulations to provide oleophobic wetting properties. However, as of February 2023, the European Chemicals Agency (ECHA) regulates more than 10,000 perfluorinated and polyfluorinated substances (PFAS). In the near future, the use of PFAS will be banned in many sectors. Even for technologies such as coalescence filtration, where oleophobicity is essential for high efficiency, the use is under strong discussion.

Since there is basically no substitute for PFAS to achieve oleophobicity, the industry is looking for F-free alternatives to improve the separation and dewatering performance of coalescence filtration.

Previously, we demonstrated a more than 30% reduction in the differential pressure of a saturated coalescent filter medium as a result of patterned modification of the downstream filter surface with a fluorine-containing finish, which can be considered a low fluorine approach. .

The current project aims to improve the separation mechanisms by patterned coalescent filters with integrated drainage nonwoven media with chemically and topologically structured surface, so that the energetic effects (surface tension) are enhanced by topographical and topological effects. Preliminary results ...