Preparation And Properties Of Polysulfone Reverse Osmosis Support Membrane

Polysulfone(PSF)flat membranes and PSF hollow fiber membranes were prepared from series of casting solutions with different compositions by immerse precipitation phase inversion. N,N-Dimethylacetamide(DMAc) was used as casting solvent, different molecular weight of Poly(ehtyleneglyeol)(PEG), Tween80 and SPSF were used as the additives. The effects of PSF content and PEG content and weight on structures and performances of the membrane were investigated. Also, the effects of hydrophilic additives Tween 80 and SPSF content on structures and performances of the PSF hollow fiber membrane were researched. Else, the effect of membrane preparation process such as air gap, coagulation bath temperature and composition and liquid core composition on the structure and properties of PSF hollow fiber membranes were also discussed. The properties of Polysulfone membranes were characterized by the pure water flux, retention rate, porosity, average pore diameter, SEM and so on.The results showed that with the PEG weight and content and PSF content increasing, the viscosity of the polysulfone casting solution raised,the cross-section morphology of the membrane changed from the typical finger hole to sponge hole structure. The cross-section morphology of the membrane was sponge hole structure when the viscosity of casting solution was higher than that of 8.25Pa·s.Under the same experimental conditions, with increasing PEG molecular weigh, the average pore diameter and porosity decreased slightly, the pure water flux also declined, and the bovine serum albumin(BSA) rejection kept consistent, meanwhile, the mechanical strength of membrane reduced; With in increasing PEG content, the flux of pure water firstly increased and then decreased, while rejection was opposite. When PEG/DMAc=0.8, the pure water flux of PSF membrane was lowest, but the rejection was higher than 90%, and the cross-section morphology of the membrane was mainly composed of sponge structure. With PSF content increasing, the pure water flux increased and the rejection decreased. But with the PSF content continued increasing, the pure water flux of the membrane was rebounded and the BSA rejection decreases. When the content of PSF was 20%, the comprehensive performance of PSF hollow fiber membrane was the best. Else, the pure water flux of PSF hollow fiber membrane increased with air gap(pre-evaporation time) and coagulation bath temperature increasing while the BSA rejection decreased.The hydrophilic additives Tween80 and SPSF added in the casting solution was order to improve the PSF hollow fiber membrane permeability. It was found that the surface contact angle of PSF membranes decreased and the hydrophilic increased, and the flux of pure water firstly increased and then decreased with the increase of Tween 80 and SPSF, while rejection was opposite, but the degree of SPSF improving the permeability of PSF hollow fiber membrane was higher than Tween80. With the SPSF content continued increasing, the BSA rejection reduced largely because of the compatibility problems of PSF and SPSF, and the PSF hollow fiber membrane had the best comprehensive properties when the content of SPSF was 1.5%. Besides, the average pore diameter and the porosity of PSF hollow fiber membrane increased whether it was to add the DMAc into the coagulation bath or liquid core, so the flux of pure water increased with DMAc content increasing and the BSA rejection decreased.