Effect of Alcohol as Additives on the Morphology and Separation Performance of Polyethersulfone (PES) Hollow Fiber Ultrafiltration Membranes


Hollow fiber ultrafiltration (UF) membranes were prepared using Polyethersulfone(PES), alcohol (n-Propanol) as additive and N, N-dimethylacetamide (DMAc) as asolvent. Asymmetric hollow fiber UF membranes were spun by wet phaseinversion method from 17 wt% solids of PES/additive/NMP solutions. The alcoholadditive was n-Propanol while the external coagulant was water. Effects of n-Propanol concentrations in the dope solution on morphology and separationperformance of PES hollow fiber UF membranes were investigated. UFmembranes were characterized in terms of scanning electron microscope (SEM)while UF experiments were conducted using polyethylene glycol (PEG20,000MW)and poly (vinyl pyrrolidone) (PVP 40,000MW), as a solute. It was found that the PESUF membrane morphology changed from long two finger-like structure through ashort two finger-like structure to the two void-like structure as n-propanolconcentration in the dope solution increased from 5 to 20 wt % using water as abore fluid; pure water permeation fluxes (PWP) increased from 47 to 201L/m2.h.bar while rejections of PEG MW20,000 and PVP MW40,000 for wet-spunPES hollow fiber membranes were decreased with increased of n-propanolconcentration up to 20%. Using above method, PES hollow fiber UF membranewith high pure water permeation flux could be prepared while the molecularweight cut-off of PES hollow fiber membranes is approximately 20,000.