Positively charged nanofiltration membrane based on cardo poly(arylene ether sulfone) with pendant tertiary amine groups

The goal of the present work is the development of nanofiltration membranes by the phase inversion technique using a newly developed polymer, cardo poly(arylene ether sulfone) with pendant tertiary amine groups (PES-TA). The obtained membranes were characterised in terms of their water flux, salt and basic dye rejections, the cross-sectional and surface morphologies, surface charge characteristic, and chlorine tolerance. A typical membrane (M-40) exhibited moderate rejection to salts (36.6% to NaCl, 63.3% to MgCl2 and 70.2% to FeCl3), but high rejection to basic dyes (>98%). Zeta potential measurements indicated that the PES-TA membranes were positively charged below pH 10.7. The M-40 membrane showed excellent chlorine tolerance. After exposure to an aqueous NaOCl solution (active chlorine concentration ≥1000 ppm) for 20 days, the rejection of membrane was not changed. In addition, the obtained membrane showed efficient separation of basic dyes in the presence of NaCl salt.