High flux thin film composite (TFC) membrane with non-planar rigid twisted structures for organic solvent nanofiltration (OSN)

Abstract

Organic solvent nanofiltration (OSN) has become an emerging green and efficient technique for the separation and purification of organic solvents. The key of the industrial application of this technique is OSN membrane. Till now, current OSN membranes still have relatively low solvent permeance due to the high hydraulic resistance of the dense structure of the OSN barrier layer. Herein, a thin-film composite (TFC) polyamide-polyarylate OSN membrane containing polymers of intrinsic microporosity (PIMs) structure was successfully prepared via interfacial polymerization (IP) using a kind of hydrophilic monomer with rigid twisted structure as aqueous co-monomer together with m-phenylenediamine (MPD). The added co-monomer remarkably enhanced the perm-selectivity of the prepared OSN membrane, with an increase of more than 1.5 times for ethanol permeance, while maintaining the rejection of rhodamine B (RDB, 479 Da) above 99% under the optimal conditions. Moreover, the prepared OSN membrane has a much high permeance to polar solvents, e.g., 110.5, 112.6 and 95.8 L m−2h−1 MPa−1, for ethyl acetate, methanol and DMF, respectively. The most exciting aspect of the prepared OSN membrane is its superior solvent resistance in strong polar organic solvent. It maintained an essentially unchanged solute rejection during 63 d immersion in DMF at 80 °C, and during 120 h continuous cross-flow filtration of the RB-DMF solution at room temperature, which is superior over most of the state-of-the-art literature works, indicating its broad application prospects for separation and purification of polar organic solvent systems.