Development of high-performance organic solvent-resistant thin-film composite membranes for small molecule separation via an enhanced interfacial polymerization strategy

The increasing demand for the separation of organic mixtures in the coal tar wastewater treatment and the medical industry has made the development of nanofiltration membranes with exceptional resistance to organic solvents. Polytetrafluoroethylene (PTFE) membranes are regarded as ideal materials for the preparation of organic solvent-resistant nanofiltration (OSN) membranes due to their unique chemical stability and low surface energy. The hydrophobic nature of PTFE materials makes it difficult to create a polyamide (PA) active layer through conventional interface polymerization (IP) methods. Interestingly, a reverse interface polymerization process combined with a polydopamine (PDA) layer successfully solved the material defect. This modification process aims to successfully create a defect-free PA active layer on the PTFE support. The new strategy can effectively solve the problem of uneven wetting of the aqueous phase on the hydrophobic substrate in the traditional interface polymerization process. The prepared thin-film composite (TFC) membrane showed excellent nanofiltration performance in organic solvents. The rejection rates of phenol are 56.12 % and 67.02 % with the Mrev-PTFE-PA TFC and M_PDA-PTFE-PA TFC membranes, respectively, while the organic solvent permeation fluxes are 19.8 and 17.52 L·m⁻²·bar⁻¹ ·s⁻¹ , respectively. Our work focuses on the development of high-performance PA TFC nanofiltration membranes with high resistance to polar organic solvents. This work demonstrates a promising strategy for fabricating OSN membranes specifically tailored to the efficient separation of phenol from organic solvents, thereby highlighting their significant potential in phenolic wastewater treatment and the recovery of valuable phenolic compounds from coal tar.