Influence of nitrogen/phosphorus-doped carbon dots on polyamide thin film membranes for water vapor/N2 mixture gas separation

Nanoparticles have been attracting attention because they can significantly improve the performance of membranes when added in small amounts. In this study, the effect of polyamide membranes incorporating hydrophilic nitrogen/phosphorus-doped carbon dots (NP-CDs) to enhance water vapor/N2 separation has been investigated. NP-CD nanoparticles with many hydrophilic functional groups are synthesized from chitosan by a one-pot green method and introduced to the surface of the polysulfone (PSf) substrates by interfacial polymerization reaction. The mean particle diameter of NP-CDs, estimated from transmission electron microscopy images, is 2.6 nm. By adding NP-CDs (0–1.5 wt%) to the polyamide layer, the contact angles of the membranes dramatically decreased from 65° (PSf) to