A Path to Ultraselectivity: Support Layer Properties To Maximize Performance of Biomimetic Desalination Membranes

Reverse osmosis (RO) has become a premier technology for desalination and water purification. The need for increased selectivity has incentivized research into novel membranes, such as biomimetic membranes that incorporate the perfectly selective biological water channel aquaporin or synthetic water channels like carbon nanotubes. In this study, we consider the performance of composite biomimetic membranes by projecting water permeability, salt rejection, and neutral-solute retention based on the permeabilities of the individual components, particularly the water channel, the amphiphilic bilayer matrix, and potential support layers that include polymeric RO, nanofiltration (NF), and porous ultrafiltration membranes. We find that the support layer will be crucial in the overall performance. Selective, relatively low-permeability supports minimize the negative impact of defects in the biomimetic layer, which are currently the main performance-limiting factor for biomimetic membranes. In particular, RO membr...