Elucidating the role of graphene oxide layers in enhancing N-Nitrosodimethylamine (NDMA) rejection and antibiofouling property of RO membrane simultaneously

Water reclamation using reverse osmosis (RO) has become an indispensable component of the urban water supply system. However, the removal of low molecular weight contaminants of emerging concerns such as N- Nitrosodimethylamine (NDMA) from RO is challenging, thereby raising serious safety concerns about reclaimed water. Herein we modify RO membrane with graphene oxide (GO) using polydopamine (PDA) as crosslinking agent. The modification of commercial RO membrane via co-deposition of PDA-GO subsequently resulted in superior NDMA rejection (83 +/- 3.57%) when compared with the membranes modified via GO, PDA, GO on PDA impregnated surface, and pristine RO. The narrow interlayer spacing of the GO (0.36 nm), attributed to its partial reduction occurred due to thin PDA layer formation on its both sides, exhibited enhanced sieving effect in addition to the coverage of free-volume hole-size of the polyamide layers which offered hindrance to NDMA permeation. In addition, CFU-enumeration and confocal laser scanning microscopy revealed that the partial reduction of GO did not significantly affect its associated antibacterial property when compared with the membrane modified via GO after PDA impregnation. However, enhanced antibiofouling performance was observed using optical coherence tomography (OCT) employed in this study for in-situ, real-time, and non-destructive fouling monitoring with better flux performance.

Automated summary

The modification of reverse osmosis (RO) membranes with graphene oxide (GO) using polydopamine (PDA) crosslinking agent improves NDMA rejection and antibiofouling performance, making it an effective method for water reclamation.