Photothermal-driven interfacial-polymerized ultrathin polyamide selective layer for nanofiltration

Synthesizing defects free, mechanically robust, thin polyamide (PA) selective layer with sufficient channels for boosted permeance/selectivity of the thin-film composite (TFC) nanofiltration (NF) membranes are the central issues which impede the lab-made nanoseparation membranes commercialization. In this work, a new approach is developed to synthesize thin PA layer by light-driven interfacial-polymerization (IP) via photothermal effect from Fe-TCPP metal organic frameworks (MOFs) nanofibers inter-layer. The Fe-TCPP nanofibers convert the illuminating visible light into heat (high local temperature) and provide to PA polymerization, ultimately synthesizing robust, thin, hydrophilic PA selective layer. After removing the Fe-TCPP nanofibers layer from the prepared thin PA film with Fe-TCPP nanofibers (TFN) NF membrane, the PA of the thin-film composite (TFC) NF membrane is enforced enough to sustain high pressure of 8 bars. The resulted TFC NF membrane shows boosted methanol and acetonitrile permeances of 120 and 160 L·m−2·h−1·bar−1 with 97% rejection to acid fuchsin dye. The nanofiltration membranes show stable separation performance in both organic and aqueous mediums and have potential for organic solvent nanofiltration (OSN) and dye-wasted water nanoseparation. This photothermal-driven interfacial-polymerization will open doors for typical TFC nanofiltration/reverse osmosis membranes.