Water-diesel secondary dispersion separation using superhydrophobic tubes of nanofibers

In diesel engines, sulfur and nitrogen compounds present in the fuel forms oxides during combustion. In the presence of water, these oxides form acidic products which leads to corrosion of engine parts. Hence, it is desired to remove water from diesel fuel before it enters the engine. In this work, superhydrophobic nanofiber mat filters are fabricated in flat sheet and cylindrical geometries by the process of electrospinning and are tested for separation of water dispersions in diesel fuel. Superhydrophobic surfaces are oleophilic due to their low surface energy. The superhydrophobic nanofiber mat acts as a barrier in restricting water droplets while allowing the non-aqueous phase to easily flow through it. The cylindrical nanofiber filters performed with separation efficiency as high as 98% on a total mass basis for water drops in the range of 7-50 microns in ultra low sulphur diesel fuel (ULSD) with a face velocity of 1.55 cm/min. The flat filter geometry performed at about 92% separation efficiency at a similar face velocity. This work shows practical water-diesel separation filters can be constructed in tubular geometries.