There have been numerous articles published on formulating and casting unreinforced hollow fiber membranes. However, there are far fewer reports on preparation of reinforced PVDF hollow fiber membranes. Consequently, there has not been much study on key process parameters affecting reinforced hollow fiber membrane quality. We recently completed an experimental design study on casting reinforced PVDF hollow fiber membranes. Our goal was to understand the effects of formulation and casting conditions on membrane properties. We looked at pure water permeability, membrane coating thickness, morphology, penetration depth into the braid, burst pressure, and pore size. We found significant correlations on membrane properties with solids content of the formulation, PVDF resin content, line speed, and dope pumping speed. These variables affected permeability, membrane thickness and penetration depth the most. We found no correlations with formulation additive content, which was a big change from our past experience with unreinforced membranes. We found several formulations with good properties and one that can serve as a model formulation for end users. We will also discuss a new liquid-liquid porometry method we developed for testing hollow fiber membranes. This method is based on a liquid permeability test, in contrast to the typical gravimetric method used on other LLP instruments. During this study, we discovered a major problem with the isobutanol-water liquids typically used in the LLP method and how we used an alternate fluid combination to solve this problem.
This presentation is available to AMTA Members only.
- Walter Kosar
- Arkema Inc.
- AMTA/AWWA Membrane Technology Conference, West Palm Beach, FL
- AMTA/AWWA Membrane Technology Conference
- Hollow Fiber, Membrane Bioreactors, PVDF