1 Department of Physics, Technical University of Denmark2 Biophysics and Fluids, Department of Physics, Technical University of Denmark3 Department of Environmental Engineering, Technical University of Denmark4 Singapore Membrane Technology Centre5 Aquaporin A/S6 Nanyang Technological University7 Aquaporin A/S
Aquaporins are water channel proteins with high water permeability and solute rejection, which makes them promising for preparing high-performance biomimetic membranes. Despite the growing interest in aquaporin-based biomimetic membranes (ABMs), it is challenging to produce robust and defect-free ABMs that can be easily scaled up. We have constructed robust thin film composite (TFC) ABMs with surface areas up to 600 cm2 prepared by interfacial polymerization where Aquaporin Z-containing proteoliposomes were added to a m-phenylene-diamine aqueous solution thereby creating a polymer-rich film on top of a support membrane. Control membranes, either without aquaporins or with the inactive AqpZ R189A mutant aquaporin served as controls. The separation performance of the membranes was evaluated by cross-flow forward osmosis (FO) and reverse osmosis (RO) tests. In RO the ABM achieved a water permeability of ~ 4 L/(m2 h bar) with a NaCl rejection > 97% at an applied hydraulic pressure of 5 bar. The water permeability was ~40% higher compared to a commercial brackish water RO membrane (BW30) and an order of magnitude higher compared to a seawater RO membrane (SW30HR). In FO, the ABMs had > 90% rejection for urea and a water permeability around 10 L/(m2h) with 2M NaCl as draw solution. Our results demonstrate the feasibility of using aquaporin proteins in biomimetic membranes for technological applications.