Layered Hydrophilic/hydrophobic Fiber Media for Water-in-oil Coalescence

Fibrous coalescing filters are commonly used to separate water-in-oil emulsions. Wettability of the fibers significantly influences the filter performance. The wettability of the filter media depends on surface properties of fiber materials and porosity of the filter medium. The wettability of the filter media is characterized using modified Washburn’s equation and expressed in terms of the lipophilic to hydrophilic (L/H) ratio. In this work, layered media were prepared with varying compositions of hydrophilic micro glass fibers and hydrophobic polypropylene or polyester fibers to achieve a range of L/H values. By varying the fiber composition and thickness of hydrophilic and hydrophobic layers in the media, filter media with different wetting properties can be prepared. Water and Viscor-1487 oil (a diesel fuel calibration fluid) were used as test liquids for the wettability characterization. The filter media were tested in liquid–liquid coalescence experiments in which fine emulsions of water droplets were dispersed in the Viscor-1487 liquid. The experimental results show that the layered hydrophilic/hydrophobic structures significantly reduce the pressure drop and improve the filter performance as compared to media constructed with only micro glass fibers