Preparation and performance of SPPES/PPES hollow fiber composite nanofiltration membrane with high temperature resistance

Sulfonated poly(phthalazinone ether sulfone)/poly(phthalazinone ether sulfone) (SPPES/PPES) hollow fiber composite nanofiltration membrane was prepared by coating a SPPES layer on top of the PPES hollow fibers via the dip-coating method. Effects of the composition of coating solution and preparation conditions as well as the operating conditions on the performance of the SPPES/PPES composite membrane (CM) were investigated. It was found that an optimum rejection ratio of CM1 for 1000 mg/L Na2SO4 solution was 93.6%, and the pure water flux was 8.7 L/(m2·h) under an operating pressure of 0.35 MPa at 20 °C. The flux of CM1 can be up to 58 L/(m2·h) with the operating temperature increased from 20 °C to 90 °C, while the rejection for 1000 mg/L Na2SO4 solution only had a slight change at the pressure of 1.0 MPa. Furthermore, a short time stability measurement for about 200 h proved that the SPPES/PPES composite membrane had much better performance at a high operating temperature. Finally, a back-washing method was used to clean the pollution substances after the stability measurement, and performance of the composite membrane almost reached the initial value with the hydraulic washing time of 20 min at 50 °C under the pressure of 0.3 MPa.