The performance of integrally skinned polyetherimide asymmetric nanofiltration membranes with organic solvents

Nanofiltration (NF) has become an emerging technology in organic solvent systems and the preparation of organic solvent resistant nanofiltration (SRNF) membranes is the most important aspect of the technology. In this study, integrally skinned polyetherimide (PEI) asymmetric nanofiltration (NF) membranes were prepared by phase inversion in which dimethylacetamide (DMAc) and polyvinyl pyrrolidone (PVP-K30) were employed as solvents and additives in casting solutions. The prepared PEI membranes were characterized by scanning electronic microscopy (SEM) and evaluated in terms of solvent compatibility, solute rejection and solvent flux. The solvents employed were ethanol, isopropyl alcohol, n-hexane and carbon tetrachloride and the solute molecules were rose bengal (molecular weight 1017 Da) and methylene blue (molecular weight 374 Da). The prepared PEI NF membrane was compared with four commercial SRNF composite membranes (MPF-34, MPF-44, STARMEM 122 and Solsep 010706). The results demonstrated that the PEI membranes were stable in all of the four solvents studied and showed better performance than the four commercial SRNF membranes with regard to solvent compatibility and rejection from ethanol solutions. The PEI membrane had ethanol fluxes of 4-8 L m−2 h−1 at 100 psi and 95% rejection for methylene blue in ethanol.