Antifouling nanofiltration membrane atop nanofibrous scaffold with periodical diagonal microprotrusion

Abstract

Tuning the surface structure and roughness of selective layer is effective but a challenge to enhance the permeance and antifouling performance of nanofiltration membrane without sacrificing selectivity. In this work, we developed a novel method to engineer an aromatic polyamides (PA) selective layer atop nanofibrous scaffold with periodical diagonal microprotrusion, which inherits from the morphology of twill fabric. The hydrophilic nanofiber layer presents a compact feature (pore size: 100–300 nm) and high conformality towards the fabric support with twill morphology beneficial to the IP process. The generated PA nanofiltration membrane presented a hierarchical surface structure involving periodical diagonal microprotrusion (around 85 μm cell distance) and ridge-valley structure (∼100 nm). The resultant membrane exhibited not only a high permeance of 31.7 L m−2 h−1 bar−1 and a rejection rate of 97.5% to Na2SO4 solution, but also ameliorated antifouling performance with a high flux recovery rate larger than 96.5% in five filtration-washing tests. This is attributed to the synergistic effects between highly porous nanofiber scaffold and the eddy self-cleaning function derived from periodical diagonal microprotrusion of the fabric supported by the numerical simulation study. This work presents the superiority in designing high permeable membranes with excellent antifouling performance for advanced nanofiltration application.