Interfacial polymerized polyamide nanofiltration membrane by demulsification of hexane-in-water droplets through hydrophobic PTFE membrane: Membrane performance and formation mechanism

Abstract

• Emulsion mediated interfacial polymerization. • Demulsification of hexane-in-water droplets by hydrophobic PTFE membrane. • Controlled release of TMC during interfacial polymerization. Interfacial polymerization has been considered as a benchmark strategy for polyamide membrane fabrication. However, controlled reaction is still challengeable. Herein we propose a novel emulsion mediated interfacial polymerization strategy for controllable polyamide nanofiltration fabrication. Hexane micro-droplets containing trimesoyl chloride (TMC) molecules were adsorbed, demulsified and transported to the interface from hexane-in-water emulsion by a hydrophobic and oleophilic polytetrafluoroethylene (PTFE) membrane for further controlled reaction with piperazine (PIP). Surface morphologies, layer thickness, surface chemistry, crosslinking and water contact angle of resulted polyamide membranes were studied with varying reaction time, displaying the control for interfacial polymerization. PTFE membrane assisted interfacial polymerization strategy leads to smoother (Ra = 8.0 nm) and thinner (25 nm) polyamide layer compared with conventional interfacial polymerization. The resulted membrane exhibits comparable nanofiltration performances (water permeability: 7.3 Lm −2 h -1 bar −1 , Na 2 SO 4 rejection: 92.3%) with conventional membranes. The current study provided a new avenue for controllable interfacial polymerization.