Highly permeable and shelf-stable aquaporin biomimetic membrane based on an anodic aluminum oxide substrate

Aquaporin (AQP) biomimetic membranes are a coming-of-age technology for water purification. Although several studies have reported aquaporin biomimetic membrane fabrication to date, these membranes show low water flux mainly due to the low porosity and inherently dense structure of the polymeric substrate materials. Herein, we report a ceramic-based aquaporin biomimetic membrane based on anodic aluminum oxide (AAO) as a substrate, which has a uniform porous structure with a high aspect ratio and pore density compared to conventional polymer substrates and exhibits a high water flux of 27.6 ± 3.6 LMH (L m−2 h−1) and superior membrane selectivity of 0.11 g L−1. Briefly, the AAO substrate was functionalized with amino-silane followed by polydopamine coating, then the AQP vesicles were immobilized on the functionalized AAO substrate surface using an electrokinetic method, and the water rejection performance of the membrane was analyzed in a forward osmosis system. Furthermore, a simple cryodesiccation method is introduced to improve the storage stability and easy transportation of aquaporin membranes, which does not require special environmental conditions to transport or store them.