Alkali resisting polyphenylsulfone ultrafiltration membrane with tailored microstructure

Polyphenylsulfone (PPSU) was employed to fabricate novel alkali resisting ultrafiltration membranes via phase inversion process and the membrane structure was tailored by adjusting the kinetics of phase separation. The effects of polyvinylpyrrolidone (PVP) molecular weight (Mw) and concentration on the casting solution and the performance of PPSU membrane such as tensile strength, morphology, hydrophilicity, pure water flux (PWF), and molecular weight cutoff (MWCO) were investigated. Scanning electronic microscopy (SEM) results showed that the membrane possessed a typical asymmetric structure, and the support layer can be tailored from finger-like structure to be sponge-like structure by adjusting the kinetics of the system during phase inversion. The maximum PWF reached to 69 L m⁻²·hr⁻¹ at the transmembrane pressure (TMP) of 1.0 bar, and the corresponding MWCO ranged from 2 kDa to 175 kDa. Then the thermal and chemical stabilities of PPSU, polysulfone (PSf) and polyether sulfone (PES) membranes were investigated. The results showed that PPSU membrane possessed better thermal stability than PSf and PES membrane, and can work stably in alkali aqueous solution with pH of 13.