Membrane distillation (MD) is a promising method for recovering fresh water from warm and high salinity wastewater. In a typical MD process, hydrophobic microfiltration (MF) membrane is applied to allow water vapor transport from feed to distillate down a temperature gradient. However, MD process suffers from permeation lose due to serve membrane fouling and salt scaling. In addition, the “temperature polarization” in the boundary layer between bulk flow and membrane surface reduces the thermal gradient. Therefore, the permeation reduction due to membrane fouling and polarization phenomena ultimately diminish the economic viability of MD system.<br/><br/>In this work, we developed a novel robust microporous membrane to realize low-fouling surfaces that can potentially address these challenges whereby improve the MD efficiency over long-term operation. This is achieved by fabricating microporous membrane with micron-scale biomimicry topological features, namely patterns, through lithographically templated thermally induced phase separation (It-TIPS). Surface patterns have been experimentally demonstrated to promote turbulence in the vicinity of membrane surface, increase local shear force, and enlarge active surface area; therefore, increasing local mass transfer in boundary layers and making membrane more foulant resistant and more permeable. In this presentation, I will discuss the material formulation of It-TIPS process and enhanced MD performance in presence of surface patterns. Furthermore, the implication of It-TIPS-parameters including solvent types, polymer molecular weight, and molding pressure on patterned membrane fabrication will also be illustrated.

Surface patterning microporous membranes using lithographically templated thermally induced phase separation: Fabrication and membrane distillation performance

ACS Spring 2022

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