Design of robust twisted fiber bundle-reinforced cellulose triacetate hollow fiber reverse osmosis membrane with thin separation layer for seawater desalination

In general, the twisted fiber bundle with good fiber cohesion could be regarded as a new kind of supporting layer. Herein, a new type of poly(p-phenyleneterephthalamide) (PPTA) twisted fiber bundle-reinforced (FR) cellulose triacetate (CTA) hollow fiber reverse osmosis (RO) membrane was fabricated using a twin-screw spinning machine by the melt spinning method. Moreover, the morphologies, surface analysis and permeability of FR CTA hollow fiber RO membrane were investigated by scanning electron microscopy, confocal scanning microscopy and filtration performance. The CTA separation layer exhibited the favorable interfacial bonding state between CTA separation layer and PPTA twisted fiber bundle supporting layer. Especially, the advantages of FR CTA hollow fiber RO membrane could overcome the negative effect of permeability flux loss, due to the easy vulnerable to the compaction of CTA membrane when operating at moderate or high pressure process. Besides, the tensile strength increased from 9.2 to 96.8 MPa because of the higher interfacial stress transfer coefficient, which was achieved due to the interfacial bonding of FR CTA hollow fiber RO membrane. Besides, based on the filtration performance and long-term running test, FR CTA hollow fiber RO membrane with thin separation layer not only produced higher and more stable permeability flux while their salt rejection were basically the same, but also came into being smaller amount of deformation without defects than pristine CTA hollow fiber RO membranes after 200 h operation.