Tunability of Polyaniline Phase-Inverted Membranes for Forward Osmosis Applications

Many technologies exploiting the process of osmosis have been introduced to augment the world's depleting fresh water sources. This includes a process called low energy desalination, which uses the naturally occurring process of forward osmosis (FO) to draw fresh water from seawater using a recoverable concentrated solution through a semi-permeable membrane. However, a lack of suitable membranes has slowed its development as the only commercially available FO membrane has limited chemical and pH stability. Previous research has shown that a conductive polymer called polyaniline (PANi) shows a high affinity for water when treated with acid and exhibits very high thermal and chemical stability; it has also previously been formed into high flux ultrafiltration, pervaporation and gas separation membranes. In this study, we synthesized integrally skinned asymmetric PANi-FO membranes by non-solvent induced phase separation, and characterized the membranes’ water permeability, salt permeability and structure factor as well as thermal and chemical stability. Preliminary results suggest PANi-FO membranes are distinctly more stable than the commercial CTA membrane, while water flux is higher and salt passage is lower. Through various physical and chemical post-treatments, PANi-FO membrane water flux and salt passage can be further fine-tuned. The ease of fabrication, improved stability, and ability to further tailor membrane performance suggests PANi has great potential for the production of next-generation FO membranes.