Customized membranes: needs and opportunities for moving beyond conventional interfacial polymerization for desalination membranes

Reverse osmosis (RO) has constituted most of the installed desalination capacity in recent decades. Commercial membranes offer excellent selectivity and reasonable productivity. These membranes, however, suffer from several weaknesses that stem from the use of interfacial polymerization as a means of manufacturing. The inability to control thickness, adjust easily to new chemistries, and avoid surface roughness that enhances foulilng propensity are a few of the weaknesses to conventional membrane fabrication. Numerous materials have been proposed as alternatives to polyamide for RO in recent decades. However, in spite of numerous publications on these new materials, it is remarkable to see how none has even come close to succeeding in replacing conventional RO membrane materials in a commercial setting. This is largely because many of these new materials are incompatible with existing membrane manufacturing approaches such as interfacial polymerization. We must be able to process new materials into thin, defect-free films on conventional supports. This is a significant hurdle for new material adoption in membranes today. New manufacturing methods are needed to address the inherent weaknesses of interfacial polymerization for polyamide and the general processing of newly discovered materials into thin film composite membranes for RO and nanofiltration platforms.