Fabrication of thermally stable polyamide nanofiltration membranes via interfacial polymerization modulated with acid acceptors

Traditional polyamide nanofiltration (NF) membranes are not applicable to high-temperature separation because of insufficient thermal stability. Modulation of the interfacial polymerization process is effective in improving the high-temperature separation performance of NF membranes. Herein, we introduce an interfacial polymerization strategy modulated with acid acceptors to prevent HCl, a byproduct in interfacial polymerization, from protonating amine monomers, and hence increase the compactness and thermal stability of the polyamide selective layers. The thickness, water contact angles, and charge properties were investigated. The optimized NF membranes show high-temperature separation performance with 97.7 % rejection to MgSO 4 and 24.4 L·m −2 ·h −1 ·bar −1 of permeance at 85 °C. The membranes also exhibit thermally stable separation performance at different salt concentrations, applied pressure, cycling temperature variations, and 100-h long-term operations. This study presents an inspiring method for preparing thermostable polyamide membranes.