Interfacial polymerization of thin film selective membrane layers: Effect of polyketone substrates

Thin film composite (TFC) membranes are the most widely used technology in reverse osmosis (RO)-based desalination processes, due to their desirable separation performance derived from the combined structure of the porous support and thin film active layer. Typically, TFC membranes are fabricated via an interfacial polymerization (IP) technique, where the porous substrate plays an indispensable role in forming the thin film layer. In this study, a porous polyketone membrane with a fibrous structure and intrinsically moderate hydrophilicity prepared using non-solvent induced phase separation (NIPS) was employed as the substrate to explore its suitability for fabricating high-performance TFC membranes. Investigations on structure control and chemistry regulation via the NIPS process and in-situ post-treatment revealed that porous polyketone substrates display different morphologies and chemistries, significantly altering the thin layer formation during IP. The resulting TFC membranes exhibited up to 14-fold permeance difference, which was attributed to the variance of "ridgeand-valley" structures in different thin film layers formed on different polyketone substrates. It was found that a polyketone membrane with an appropriate surface roughness could generate favorable "ridge-and-valley" structures in the thin film layer to enhance the surface area, realizing high water permeance as well as high salt rejection in reverse osmotic desalination of NaCl solution.