ABSTRACT
Membranes are widely used in many fields, including wastewater treatment, gas purification/enrichment, fuel cells, dialysis, forward/reverse osmosis (RO), batteries, food technology, electro-deionization, pharmaceuticals, etc. 1 – 4 Membranes for separation can be categorized based on their pore size for different applications, for example: 10–100 μm for conventional filtration, 0.1–10 μm for microfiltration (MF), 50–1000 Å for ultrafiltration (UF), and smaller than 50 Å for RO and gas separation. 5 The driving forces for separation can be the gradients of concentration, temperature, pressure, and/or external/internal electric potential. Materials for fabricating membranes include organic, inorganic, ceramic, polymeric, and mixtures of these. Most commercial membranes are polymeric due to their advantages of low cost and the ability to use roll-to-roll processing. Here, we focus on applications of conjugated polymers for selected separations. First, conjugated polymer–based gas separation membranes using polyaniline will be introduced, followed by the use of other conjugated polymers and then composite membranes (Section 21.1). Second, conjugated polymer–based membranes for water purification will be discussed (Section 21.2), followed by the emerging field of capacitive deionization (Section 21.3). This review highlights the synthesis, mechanisms, and performances of membrane technologies that specifically use conjugated polymers.
