Braid-reinforced polybenzimidazole (PBI) hollow fiber membranes for organic solvent nanofiltration (OSN)

Abstract

A braid-reinforced polybenzimidazole (PBI) hollow fiber membrane has been reported, which was made by our in-house developed spinning devices. The braid elements not only remarkably increase the mechanical strength of the PBI hollow fiber membrane to more than 100 Mpa but also maintains its low swelling ratio of less than 2% even in harsh organic solvents compared with the self-support PBI hollow fiber. The effects of PBI dope concentration, flow rate and wetting agents for braid co-extrusion on the structure and separation performance of braid-reinforced hollow fibers have been investigated. The spinneret design and the braid handling device are also discussed. The recently developed braid-reinforced PBI hollow fiber membrane has a rejection of Rose Bengal (RB) over 90% in methanol (MeOH) with a permeance up to 3.6 Lm-2h-1bar-1 compared with the self-support hollow fiber under high pressure. In addition, the braid-reinforced membrane has a slightly higher rejection and a stable separation performance over 40 h than the self-support one because the former has a lower swelling ratio than the latter one. Due to the favorable interfacial bonding between the PBI coating layer and the reinforced elements, the braid-reinforced PBI hollow fiber membrane can withstand an operation pressure of exceeding 10 bar, which exhibits its great prospects for solvent resistant nanofiltration (SRNF) applications.