Towards enhanced antifouling and flux performances of thin-film composite forward osmosis membrane via constructing a sandwich-like carbon nanotubes-coated support

In this work, we fabricated a sandwich-like single-walled carbon nanotubes (SWCNTs)-coated support for the preparation of high-performance antifouling thin-film composite (TFC) forward osmosis (FO) membrane. This sandwich-like support was prepared through the deposition of polydopamine modified SWCNTs (PDA-SWCNTs) on both sides of the polyethersulfone (PES) microfiltration (MF) membrane. The CNTs top layer was found to facilitate the formation of polyamide layer. The CNTs back layer provided an antifouling surface for the prevention of foulants adsorption and intrusion into the PES support. Results demonstrate that the CNTs back layer imparted superior rejection towards bovine serum albumin (BSA) (similar to 98.1%) and enhanced hydrophilicity. The TFC FO membrane (TFC-modified) having the sandwich-like SWCNTs-coated support exhibited excellent perm-selectivity with the water flux J(w) of 35.7 Lm(-2) h(-2) and the reverse salt flux J(s) of 1.42 gm(-2) h(-1) when tested in the mode of active layer facing to draw solution (AL-DS) using 1 M NaCl as a draw solution. Dynamic fouling experiments confirm that the TFC-modified membrane possessed effective antifouling performances with a low relative fouling degree (RFD) of 19.0% during the cross-flow run and 8.4% during the BSA adsorption test, which were much lower than the corresponding values of 36.1% and 15.4% for the TFC-control membrane.