Sulfonated poly(ether ether ketone) based composite membranes for nanofiltration of acidic and alkaline media

► Composite SPEEK based nanofiltration membranes. ► Permeance and MWCO in nanofiltration range, tailored by degree of thermal cross-linking. ► No irreversible performance change in long-term exposure to acidic/alkaline conditions. ► MWCO analysis at relevant acidic/alkaline conditions.