Polyethylenimine grafted hollow fiber membranes for fast dye separation

Hollow fiber membranes (HFMs) are widely used in nanofiltration for dye separation. However, the majority of HFMs suffers from the “trade-off” relationship between permeance and rejection. Here, we demonstrate a facile strategy to prepare polyethylenimine (PEI) grafted polyethersulfone (PSF-PEI) HFMs for fast dye separation with high rejection. Different from traditional interfacial polymerization, the nanofiltration HFMs were directly fabricated via quaternarization of PEI on brominated polyethersulfone (PSF–Br) ultrafiltration HFMs. Compared to other reported works, the prepared PSF-PEI HFMs exhibit ultra-high water permeance of 150 L m⁻² h⁻¹ bar⁻¹ along with outstanding rejection of over 98% for several kinds of dyes and low rejections (<20%) for inorganic salts. Impressively, the PSF-PEI HFMs also have excellent stabilities and antifouling abilities, which can be operated stably at complex environment for a long time with dye rejection of higher than 99%. Therefore, the prepared HFMs show great potential in industrial application for fast dye separation.