Fabrication of polyimide-based hollow fiber membrane by synergetic covalent-crosslinking strategy for organic solvent nanofiltration (OSN) application

Hollow fiber (HF) membranes have attracted rising attentions recently for organic solvent nanofiltration (OSN) applications. However, till now, hollow fiber OSN membranes are rarely reported, and most of them were prepared using expensive materials or special methods that are difficult to imply. In this study, a kind of HF OSN membrane with commonly used polyimide materials was prepared by a simple and feasible covalent-crosslinking strategy using polyethylenenimine (PEI) of low molecular weight and 1,6-hexanediamine (HDA) to realize an integral crosslinking of the polyimide substrate and the skin layer, and using glutaraldehyde (GA) to further improve the dye rejection. The fabricated HF OSN membrane under optimal conditions has an ethanol permeance of 4.47 L m(-2) h(-1) MPa-1, a Rhodamine B (479 Da) rejection of 96.5%, a mean pore size of 0.69 +/- 0.27 nm, as well as a good solvent stability according to the results of a 7-days stability tests in polar and non-polar solvents, implying promising OSN applications. The synergetic covalent-crosslinking strategy reported in this work could provide insightful guidance for the fabrication of high-performance HF OSN membrane.