Permeation properties of thermo-chemically stable ultrafiltration membranes of copoly(bis[4-(3-aminophenoxy)phenyl]sulfone/3,3′,4,4′-benzophenonetetracarboxyl/pyromellite) imides

Thermo-chemically stable ultrafiltration (UF) membranes based on soluble copoly (bis[4-(3-aminophenoxy)-phenyl]sulfone/3,3′,4,4′-benzophenonetetracarboxyl/pyromellite) imides(CPIs) were prepared by conventional phase inversion and the factors determining their permeation characteristics were studied. The permeation behaviors were measured by the pure water flux and the solute rejection. The thermal stability of the UF membranes was observed by measuring the relative ratio of the permeate flux (Jt)/pure water flux(J0). The relative flux for the poly (ethyleneglycol) (PEG, MW 2.0 × 104) aqueous increased with increasing operation temperature and the performances of the CPI membranes treated with common organic solvents had the same values. The CPI membranes were easy to fabricate, because CPIs dissolved well in aprotic polar solvents. The preparation conditions and operation method proposed herein could play an important role in the permeation properties of the UF membranes. Further, the CPI membranes exhibited outstanding resistance to common organic solvents as well as thermal stability.

► The chemico-thermally stable UF membranes of copolyimide were prepared.
► The relative flux increased with increasing operation temperature.
► The UF membranes of copolyimides were easy to fabricate.
► Copolyimides dissolved well in aprotic polar solvents.