Poly(aryl ether ketone) membrane with controllable degree of sulfonation for organic solvent nanofiltration

The separation of organic solvents can be improved in a sustainable way by implementing membranes produced via streamlined processing. However, conventional membranes are not typically used in organic solvents, and thus require further chemical cross-linking before use. This process is complicated, and cross-linking agents are harmful to the environment. This study investigated the synthesis of a sulfonated poly(aryl ether ketone) (SPAEK) copolymer with a controlled degree of sulfonation via molecular design as a novel nanofiltration membrane in organic solvent. The introduction of a suitable number of sulfonic acid groups improved the hydrophilicity and surface charge of the membrane compared to conventional poly(aryl ether ketone) (PAEK), leading to excellent performance in separating alcoholic solvents and negatively charged dyes. The membrane still exhibited good separation performance, and no obvious damage to its microstructure was found by FESEM after the membrane was soaked in N,N-dimethylformamide (DMF) for 7 days. Consequently, the ethanol permeance and dye rejection of the membrane was maintained. PEK-SPEDEK membrane has potential applications in OSN under complex and harsh conditions such as printing, dyeing and pharmaceuticals.