Study of phase inversion parameters for EB-cured polysulfone-based membranes

Abstract

Asymmetric EB-cross-linked polysulfone (PSU) membranes suitable for solvent resistant nanofiltration (SRNF) were prepared via the phase inversion method. The influence of phase inversion parameters including polymer concentration, evaporation time prior to immersion and co-solvent/solvent ratio was investigated to optimize the separation performance. When the PSU concentration increased from 15 wt% to 21 wt%, rose bengal (RB) rejection varied from 84.7 to 94.3% and isopropanol (IPA) permeance decreased from 0.051 to 0.015L m⁻² h⁻¹ bar⁻¹. Rejection increased from 88.6 to 94.7%, while permeance decreased from 0.039 to 0.007 L m⁻² h⁻¹ bar⁻¹ with increasing evaporation time from 0 to 100 s for the PSU membranes cast from a solution that contained a THF/NMP ratio of 15/85. A similar impact was also obtained when the co-solvent/solvent (THF/NMP) ratio was increased from 0/100 to 30/70 at 30 s evaporation time: rejection increased from 86.3 to 96.1%, while permeance decreased from 0.042 to 0.011 L m⁻² h⁻¹ bar⁻¹. The EB-cured PSU membranes were further characterized by scanning electron microscopy (SEM) and solvent resistance tests.