Super-hydrophilic nanofiber substrate supported forward osmosis membrane with less polyamide layer defects by polydopamine-graphene oxide modification for high salinity desulfurization wastewater desalination

Super-hydrophilic electrospun nanofiber as the substrate of a thinu film composite forward osmosis (eTFC-FO) membrane can improve the performance of the membrane by mitigating internal concentration polarization (ICP). However, polyamine (PA) layer defects easily formed on super-hydrophilic nanofiber substrate hinders its further performance improvement. To prevent PA from forming deep inside the pores of substrate and alleviate PA defects, polydopamine-graphene oxide (PDA-GO) was introduced to modify the interlayer and PA layer of eTFC-FO membrane. Results showed that PA layer defects can be alleviated by addition of PDA-GO in interlayer or PA layer, and the simultaneous addition of PDA-GO in interlayer and PA layer resulted in the least defective PA layer of the eTFC-FO membrane (eTFC0.5-0.125). Performance evaluation demonstrated that the eTFC0.5-0.125 had a high FO water flux of 54.0 LMH and excellent ion rejections (>98.0%) for desalination of a real high salinity desulfurization wastewater. Besides the PA defects alleviation, nanochannel of PDA-GO for water transport also contributed to the performance improvement, as well as the fast water and salts diffusion by superhydrophilic nanofiber substrate. Thus, a high performance eTFC-FO membrane was prepared on superhydrophilic nanofiber substrate and was able to be used for high salinity water desalination.