C3N4-interlayer-mediated interfacial polymerization of homopolymer nanofiltration membranes for efficient water purification

Interlayered thin film composite (TFNi) membranes have been shown to achieve high-quality polyamide (PA) skin layers with enhanced permeability and selectivity. Herein, we demonstrate the construction of a hydrophilic interlayer by polymeric graphitic carbon nitride (g-C 3 N 4 ) for optimizing the interfacial polymerization of the nanofiltration membrane. Due to the effective enrichment and the slowed diffuse rate of amine monomer solutions, g-C 3 N 4 modification decreases the thickness of the PA skin layer and increases the electronegativity of membranes. The best TFNi membrane exhibits a high water permeance of 31.82 L m −2  h −1 bar −1 , nearly twice as high as that of the membrane without g-C 3 N 4 interlayer, while maintaining a comparably Na 2 SO 4 rejection efficiency. The stronger hydrophilicity and more negatively charged surface of the TFNi membrane effectively retarded membrane fouling , contributing to the high-efficiency removal of harmful drugs from actual surface water, with more than two times higher water flux that of commercialized NF270 membrane. This work provides a facile strategy to synthesize TFNi membranes with great application potential for high-performance nanofiltration.