Prototype aquaporin-based forward osmosis membrane: Filtration properties and fouling resistance

The trade-off between water permeability and selectivity is considered as the biggest challenge during membrane fabrication for water purification. The aquaporin (AQP)-based biomimetic membrane has been proven to have both enhanced water permeability and improved selectivity due to the unique features of the AQP protein water channel that permits water molecules and rejects all other components. In this study, a prototype forward osmosis (FO) Aquaporin Inside™ membrane (AIM) was evaluated in terms of intrinsic filtration properties, membrane surface chemistry and fouling behaviour, and compared with a commercial FO membrane. The surface of the prototype AIM appeared to be a modified semi-aromatic polyamide layer instead of fully-aromatic as in other conventional FO products. As a result, compared to the commercial FO membrane, the prototype AIM shows higher water flux and comparable reverse salt flux (RSF) when tested under identical conditions. Due to the lower RSF, the AIM had less organic fouling by a sodium alginate solution when calcium chloride (CaCl2) was used as the draw solution (DS). The membrane integrity of the prototype AIM was maintained after repeated cycles of fouling by high concentration of gypsum and physical cleaning tests. This demonstrates the possibility of using the AIM membrane for treating harsh feed solutions.