Mixed hydrophilic/hydrophobic fiber media for liquid-liquid coalescence

Abstract

An immiscible lipophilic or hydrophilic liquid phase separated respectively from a continuous hydrophilic phase or a lipophilic phase liquid. Fibers having hydrophilic and hydrophobic properties are mixed, layered, etc., and formed into a filter. The separation mechanism involves capture of small droplets of the immiscible phase, coalescence of the small droplets into larger droplets as the immiscible liquid flows through the fiber filter, and release of the large immiscible droplets from the filter. With respect to separation of a hydrophilic immiscible fluid such as water in a lipophilic continuous fluid such as oil, the hydrophobic fibers will cause small water droplets to migrate towards the hydrophilic fibers whereby large droplets are formed on hydrophilic surface. The large droplets stay on hydrophilic fiber surface for extended periods of time and continue to coalescence until they are so large that they can no longer be maintained by the hydrophilic fibers and are released and drained off of the filter. In designing such filter, wettability of the filter media is an important parameter. The filter media can be designed by mixing hydrophilic and hydrophobic fibers in various proportions to achieve an optimum wettability range for separation of the immiscible liquid from the continuous phase liquid. The wettability of filter media can be characterized by a modified Washburn Equation.