Remarkable improvement of the performance of poly(vinylidene fluoride) microfiltration membranes by the additive of cellulose acetate

In order to improve the performance of poly(vinylidene fluoride) (PVDF) microporous membranes, cellulose acetate (CA) was used as a hydrophilic additive to blend with PVDF for membrane preparation by phase inversion in a wet process. Scanning electron microscopy (SEM) revealed that the fabricated PVDF membranes have the typical asymmetric structure. The water contact angles of the PVDF membranes were decreased, the water contents of the membranes were increased, and the amounts of adsorbed protein were dramatically decreased due to the addition of CA. X-ray photoelectron spectroscopy (XPS) analysis confirmed the enrichment of CA segments on the PVDF membrane surfaces due to surface segregation for lowering of interface free energy. The shift of F 1s binding energy from 687.8 to 687.0 eV indicated that there are interactions between PVDF and the added CA. All prepared PVDF microfiltration membranes have higher flux recovery ratio and lower membrane fouling in protein separation and purification.