Reverse osmosis membrane with simultaneous fouling- and scaling-resistance based on multilayered metal-phytic acid assembly

Abstract

Mineral scaling and organic fouling are challenging and co-existing issues that compromise membrane performance in reverse osmosis (RO), but membrane materials possessing both scaling and fouling resistance have not been achieved so far. In this study, thin-film composite (TFC) polyamide membranes were modified with multilayered Ferric-phytic acid (PhA) complexes using layer-by-layer (LbL) assembly, which achieves simultaneous resistance against both silica scaling and BSA fouling. The Ferric-PhA complexes enhanced both hydrophilicity and negative charge, while decreasing the surface roughness of the TFC membrane. The Ferric-PhA assembled membranes exhibited excellent resistance against both individual silica scaling and bovine serum albumin (BSA) fouling in RO desalination, with an increase of layer number resulting in improved membrane performance. The Ferric-PhA assembled membranes further showed remarkably less flux decline compared to the pristine TFC membrane when silica scaling and BSA fouling co-existed. The favorable membrane surface properties imparted by Ferric-PhA complexes reduced the membrane interactions with both silica scalants and BSA foulants effectively, resulting in the exceptional and simultaneous scaling and fouling resistance. Our work demonstrates that it is feasible to achieve dual functions of scaling and fouling resistance of RO membranes by smart surface modification.