Members of our research team previously demonstrated that cross-linked ionic lyotropic (i.e., surfactant) liquid crystal (LLC) assemblies can be used as a new type of membrane material for molecular size-selective water nanofiltration and desalination. In particular, ordered, 3D-nanoporous, cross-linked LLC networks with a type I bicontinuous cubic (QI) phase can be prepared from an imidazolium bromide-based gemini LLC monomer. Using solution-casting techniques, thin-film composite (TFC) membranes of this QI LLC material can be prepared with uniform-size, 0.96-nm-wide ionic pores that separate dissolved molecular solutes from water via molecular sieving and charge repulsion effects. Herein, we present recent progress in exploring this TFC QI polymer membrane for use in treating hydraulic fracturing flowback water via dead-end filtration, and in treating high salinity saltwater via cross-flow filtration to see how this new membrane system performs under conditions more representative of industrial application. The advantages and disadvantages of the TFC QI membrane relative to several commercial reverse osmosis and nanofiltration membranes compared under the same test conditions will be discussed. Some approaches for modifying the chemical structure of the TFC QI membrane system to improve its separation performance in these two applications will also be presented.

Exploring and modifying ionic lyotropic liquid crystal-based nanoporous polymer membranes for different water purification applications

2019 Spring National Meeting

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