Nanofiber composite ultrafiltration membrane functionalized with cross-linked β-cyclodextrin for steroid hormone micropollutant removal

Steroid hormone (SH) micropollutants are not efficiently removed with conventional membrane processes. Cyclodextrins are macrocyclic molecules widely applied in water treatment for the removal of these micropollutants. In this study, a composite nanofiber membrane (CNM) containing cross-linked β-cyclodextrin-epichlorohydrin (βCDP) was prepared by electrospinning the functionalized nanofibers onto an ultrafiltration membrane support. The CNM membrane was evaluated for SH removal in both static adsorption and during filtration. A removal of 80 % was reached in static condition with a βCDP loading of 2.5 ng/cm2. During filtration, the hydraulic residence time, SH concentration and nanofiber matrix thickness limited SH removal and uptake. The highest removal of 76 % and uptake of 9.5 ng/cm2 were achieved with a nanofiber matrix thickness of 442 μm. Molecular dynamic simulation revealed that SH type affected the βCDP interaction and inclusion complex formation, the strongest interaction occurred with progesterone and the lowest with testosterone. This was consistent with experimental data. Overall, the results are promising for the application of this functionalized membrane for SH removal due to the high adsorption capacity and the ability to form a specific inclusion complex interaction with the SH molecules.