The AgCl-Based Mineralized Thin-Film Composites (TFC) Membrane for Forward Osmosis

The AgCl-based mineralized thin-film composites (TFC) membrane for forward osmosis

Haiyang Jin^{1, 2}, Tianmiao Lai¹, Huidan Yin¹, Pina Cay-Durgun¹, Afsaneh Khosravi¹, Mary Laura Lind¹ and Ping Yu²

¹School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA  

²College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, People's Republic of China

Forward osmosis (FO) membrane processes are emerging technologies that have demonstrated great potential in various water treatment applications. FO has many advantages including lower propensity towards fouling, lower energy, high water flux, high recovery and high quality product. However, FO still faces some critical challenges such as concentration polarization and chemical tolerance requiring further membrane development. Increasing researches have focused on preparing new FO membranes.

We synthesized novel AgCl-based mineralized thin-film composites (TFC) as forward osmosis (FO) membranes. We deposited silver chloride on the surface of the hand-cast polysulfone/polyamide (PSf/PA) membranes through surface mineralization by an alternate soaking process (ASP) in which we  repeatedly dipped the membrane into aqueous solutions of silver nitrate (AgNO₃) and sodium chloride (NaCl). We synthesized membranes with different mineralization degrees (MD) by changing the number of ASP cycles. We use SEM, EDS, AFM, Contact angle, etc. to characterize the FO membranes. The results of MD, SEM and EDS confirmed the existence of the AgCl coating layer on membrane surface. The results of AFM and contact angle showed the mineralized membrane surfaces were smoother and more hydrophilic. We tested the FO performances of the membranes at 25 ℃ with pure water as the feed solution and 1 M NaCl solution as the draw solution. We found the mineralized membranes exhibited better water flux and salt rejection than original TFC membranes and the commercial CTA-ES FO membrane. We will choose Bovine Serum Albumin (BSA) as foulant to investigate the antifouling properties of mineralized membranes.