| Polyethersulfone(PES)materials are widely used in filtration because of its excellent chemical stability and biocompatibility.However,for PES plate membrane,hydrophobicity leads to higher filtration energy consumption and less membrane life.Therefore,it is one of the important research contents of PES membrane to improve its hydrophilicity.Blending is one of the most commonly used and practical method of membrane modification.PES film blending modification is usually solution blending method,hydrophilic or other functional additives were added into the PES casting solution,and then through the phase transition into a film,polyvinyl pyrrolidone(PVP)and ethylene glycol(EG)is a commonly used hydrophilic additive.A small amount of additives improves the structure and hydrophilicity of the PES membrane.The disadvantage is that it is easily dissolved in water.In this study,PES plate membrane was prepared by phase inversion method and modified by means of blending.The effects of PVP,EG,CA and sodium methylmethanesulfonate on PES Membrane structure and their effects on silk fibroin filtration properties were studied.The film’s contact angle,water flux,porosity,average pore size,rejection rate,anti-pollution performance,micro-morphology were observed to research the performance of the film.(Ⅰ)Effect of PVP on structure and filtration performance of PES membrane.PVP had a great influence on water flux,contact angle,pore size distribution and pore size,membrane pore structure and anti-pollution performance of PES membrane.At 5%PVP,the maximum water flux and contact angle reached 360(L/m~2·h)and 72.5?.With the increase of PVP mass fraction,water flux and contact angle gradually decreased,finally reaching the equilibrium state.Porosity gradually increased up to 76%.The rejection and anti-fouling ability of PES membrane increased with the increase of PVP mass fraction.When the mass fraction of PVP was 13%,the rejection rate reached98%and the flux attenuation was10%after 120 min continuous filtration.With the addition of PVP,the number of membrane pores in the surface of PES membrane first increased and then decreased,the proportion of finger-like pores in the support layer increased,the penetration was better,and the pore size was more uniform.(Ⅱ)Effect of EG on structure and filtration performance of PES membrane.With the increase of EG mass fraction,the porosity and water flux decreased gradually.When the mass fraction of EG was 9%,the water flux decreased to 30 L/(m~2·h),the contact angle decreased to 72?and the porosity decreased to 74.5%.With the increase of the mass fraction of EG,the rejection rate of PES membrane increased up to about 95%,while the anti-fouling performance of PES membrane was improved.When the mass fraction of EG was 9%,after 120 minutes continuous filtration,the flux decayed to the original 76%.The addition of EG reduced the number of pores on the surface of the PES membrane,the extension of the finger-like pores in the support layer was better,the proportion of the finger-like pores gradually increased,the membrane pore size distribution was more uniform and the membrane pore walls were denser.(Ⅲ)Effect of CA,sodium hydroxymethanesulfonate on structure and filtration performance of PES membrane.The PES membrane prepared by CA and sodium hydroxymethanesulfonate as additive has shown that the surface hydrophilicity was best and the contact angle is 68.7?when CA was 2%.The addition of sodium hydroxymethanesulfonate can further reduce the contact angle,and the contact angle decreases to 53?when the content of sodium hydroxymethanesulfonate was 1.2%.When the mass fraction of CA was 2%,the maximum water flux reached 105 L/(m~2·h),the rejection rate was 50%and the porosity was 72%.The anti-fouling performance increased with the increase of CA mass fraction.When the mass fraction of CA was 4%,the flux attenuation was 50%after continuous filtration for 120 mins.When the mass fraction of CA was 2%,the addition of sodium hydroxymethanesulfonate was 1.2%PES ultrafiltration membrane had the best anti-fouling performance.The flux decay was 56%of the initial,the porosity was up to 74.3%,the water flux was 110 L/(m~2·h),the average pore size was 19.8 nm and the rejection rate was 50%.The addition of CA and sodium hydroxymethanesulfonate promoted the ratio of finger-like pores,making the pore walls dense and enhancing the rejection rate. |
