Surface functionalization of TFC FO membranes with zwitterionic polymers: Improvement of antifouling and salt-responsive cleaning properties

In this work, a salt-responsive thin film composite (TFC) forward osmosis (FO) membrane has been prepared by grafting poly(sulfobetaine methacrylate) (PSBMA) brushes on a commercial FO membrane surface via an ATRP reaction for advanced treatment of oil/water emulsions. By varying polymerization time, the optimum modified membrane (i.e. TFC-PSBMA) was obtained, which exhibited superhydrophilic and ultralow oil-adhesion properties. Dynamic fouling experiments using a feed solution of 10,000 ppm oil/water emulsion demonstrated the superior anti-fouling ability of the TFC-PSBMA membrane, as displayed by the lower water flux decline compared to the TFC-control membrane. Furthermore, multi-cycle FO fouling tests showed that the irreversible membrane fouling of the TFC-PSBMA membrane can be significantly alleviated by using salt cleaning in long-term use. The salt-responsive properties of the PSBMA brushes were considered to provide a driving force for the release of oil foulants from the membrane surface.