Effect of nonsolvent additives on PES ultrafiltration membrane pore structure

ABSTRACT Different nonsolvent additives, namely, diethylene glycol, n ‐butyl alcohol (NBA), and ethylene glycol monomethyl ether, were added into the casting solution (polyethersulfone/dimethylformamide/lithium chloride) to prepare ultrafiltration (UF) membrane via phase inversion. The effects of different additives and their concentration on the pore structure of the prepared UF membrane were studied. The cross‐sectional morphology of the membrane was observed via scanning electron microscopy. The addition of nonsolvent additives improved the large‐cavity structure of the membrane. When the additive was low‐content NBA (1–3 wt %), the membrane pore structure transformed from large‐cavity structure to fully sponge‐like structure. When the content of additive NBA was 3 wt %, the flux of the prepared UF membrane was 130.45 L (m −2 h −1 ), the rejection of PEG20000 was 95.54% and the flux remained high at 4 bar in long‐term stability test. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47525.