(449al) Polyacrylonitrile Supported Thin Film Composite Hollow Fiber Membranes for Forward Osmosis

Hollow fiber membranes have long been considered a valuable platform for membrane separations because of their high packing density relative to flat sheet membranes. Recently, the osmotic process community has developed hollow fiber membranes intended for forward osmosis (FO) and pressure retarded osmosis (PRO) applications in order to capitalize on these same advantages. However, this requires rethinking how the hollow fiber membrane should be made. Previous work on FO membranes demonstrated that employing a thin, highly porous, minimally tortuous and hydrophilic supporting structure is essential to mitigating concentration polarization. In this study, we use a systematic approach to fabricating a hollow fiber membrane taking into consideration these particular needs. We use a polyacrylonitrile (PAN) hollow fiber as a hydrophilic support to a thin polyamide film with excellent selective properties. This polyamide layer was formed on the outer surface of hollow fibers via interfacial polymerization. The effect of support layer structure could then be evaluated based on flux performance with some of our membranes exhibiting water flux of 36.6 Lmh using a 1 M sodium chloride draw solution against deionized water in the PRO mode. Thin fiber walls with open and straight pore structures were found to improve water flux substantially and that these structures could be readily tuned by adjusting spinning parameters.