Targeting fabrication of a TFC NF membrane for the desalination of sulfate-type brackish water

Nanofiltration (NF) is a promising technology for brackish water desalination due to its tunable separation efficiency and effective removal of organic contaminants. However, the limited diversity of commercial NF membranes hinders optimal performance. To address this, we developed a tailored NF membrane by simultaneously increasing the piperazine (PIP) concentration and decreasing the trimesoyl chloride (TMC) concentration aiming for the treatment of a typical sulfate-type brackish water. The optimized membrane demonstrated superior performance: adequate desalination capability and improved anti-fouling properties. In particular, the NF membrane fabricated with 1.5 %( w / v ) PIP and 0.03 %(w/v) TMC exhibited a more compact polyamide structure and superior desalination performance compared to NF270. In comparison to NF90, it presented greater surface hydrophilicity (~40°) and nearly two-fold higher permeation flux. Moreover, it exhibited significantly improved anti-fouling ability, as evidenced by its 99.9 % flux recovery versus NF90's 23.5 % after brine cleaning. This enhancement is attributed to its optimized solute selectivity and surface chemistry, which reduce concentration polarization and foulant adhesion. Our work provides a practical and feasible strategy for customizing NF membrane structures to improve desalination efficiency and sustainability.