Atmospheric plasma coatings for membrane distillation

Membrane distillation is an emerging membrane technology, commonly used for desalination. The development of high performing and cheap membranes is one of the concerns for increasing the industrial applicability of the technology. In this paper, an economically interesting alternative has been found through the deposition of an atmospheric plasma coating on an inexpensive commercial hydrophilic membrane with a microporous structure. This coating enables obtaining the required hydrophobicity in order to retain the feed solution and preventing wetting of the membrane. The effect of the plasma discharge time on the membrane properties and membrane distillation performance was investigated. It was found that by using atmospheric plasma technology, very thin hydrophobic layers of a few μm can be obtained on top of a hydrophilic membrane structure. The thin hydrophobic layer obtained using this technology reduces the mass transport resistance, which results in very high fluxes at seawater salinity. This flux is equal to the flux of more expensive and supported thin PTFE membranes.