3D-macrocycles impregnated polybenzimidazole hollow fiber membranes with excellent organic solvent resistance for industrial solvent recovery

Abstract

A new strategy to synthesize integrally skinned polybenzimidazole (PBI) hollow fiber membranes for organic solvent nanofiltration (OSN) has been developed in this study by means of covalent modification with α,α′-dibromo-p-xylene (DBX) and then ionic impregnation with 4-sulfocalix [8]arene (SCA8). This double modification strategy endows the PBI hollow fiber membranes with synergistically enhanced chemical stability, mechanical strength and molecular sieving property. The modified PBI hollow fibers have a molecular weight cut-off (MWCO) of 217 Da and a narrow pore size distribution. In addition, the newly developed PBI hollow fiber membranes display a broad-spectrum of applications in various polar, nonpolar, and aprotic polar organic solvents. 1-inch PBI hollow fiber membrane modules are also fabricated to concentrate 10 wt% oil/acetone mixtures under 10 bar for 30 days, which provide an acetone permeance of around 0.35 L m−2 h−1 bar−1 and an oil rejection >99.5% after stabilization. This work may propose a feasible scheme to design OSN hollow fiber membranes and fabricate industrial-size modules with sharp molecular sieving capability to realize angstrom-scale separations in organic solvents.