Nature gives the best solution for desalination: Aquaporin-based hollow fiber composite membrane with superior performance

Nature has contributed the best selective material, Aquaporin (AQP), for us. Herein we report on a highly permeable and selective hollow fiber composite membrane based on Aquaporin Z. The AQP-incorporated proteoliposomes were immobilized on the inner surface of a hollow fiber membrane substrate and subsequently coated by a polyamide layer formed by a non-gas assisted interfacial polymerization process. Morphological observation suggested that the introduced proteoliposomes were totally embedded in the polyamide layer with their intact spherical shape preserved. Hollow fiber composite membranes with different AQP covering densities were prepared and evaluated, and an elevated covering density of AQPs was found beneficial in improving the water flux and salt rejection of the resultant membrane. The biomimetic membrane with a high AQP covering density exhibited a 40Lm^-2h^-1 permeate flux at 5bar, almost 200% as much as the flux of a typical commercial reverse osmosis membrane (BW30). This membrane also exhibited above 97.5% rejection to a 500ppm NaCl solution, which was superior to the commercial membrane tested under the same conditions. Moreover, a forward osmosis test of the AQP-based hollow fiber membrane also yielded a super high water flux without a notable increase in salt back diffusion. It was therefore concluded that the integration between embedded proteoliposomes and the polyamide layer was effectively defect-free, and the remarkably enhanced water permeation was contributed by the embedded AQPs. Furthermore, it was estimated that the newly developed AQP based hollow fiber membrane could reduce the power consumption significantly if applied in a water reclamation process. The AQP-based biomimetic membrane has been designed and fabricated beyond the proof-of-concept stage and is able to offer a novel means for tailoring the membrane materials to enhance membrane performance.