Nanofiltration thin-film composite membrane on either the internal or the external surface of a polysulfone hollow fiber

The inner and outer surfaces of a porous hollow fiber polysulfone support are compared as substrates for the synthesis of polyamide thin-film composite (TFC) membranes by interfacial polymerization. While both surfaces have pores common of microfiltration membranes, the inner surface has a larger pore diameter than the outer surface (2,700 nm compared to 950 nm). The inner TFC membrane showed higher water nanofiltration permeance than the outer (2.20 +/- 0.17 compared to 0.13 +/- 0.03 L m(-2)hr(-1)bar(-1)). This was due to the influence of the porosity and roughness, which were different on both support surfaces. These membranes are interesting because they were synthesized in a hollow fiber support with a high membrane area per volume unit (similar to 6,900 m(2)/m(3)) and the substrate used was commercial, which means that the TFC membrane obtained is suitable for industrial application. A mathematical simulation of the nanofiltration run with COMSOL Multiphysics 5.3 software confirmed the experimental trends observed.