Preparation And Characterization Of Hydrophilic Polysulfone Ultrafilitration Membrane

As an outstanding membrane material,polysulfone?PSF?is one of the most extensively used polymers in the preparation of water treatment separation membrane.However,the PSF is extremely hydrophobic and easily contaminated in the application.Compared with hydrophobic membrane,a large number of studies have confirmed that hydrophilic membranes are favorable in inhibiting the adsorption of proteins onto the membrane and improving the membrane anti-fouling ability.Therefore,the hydrophilic modification of PSF is particularly important.To settle the problem above,in this study,the PSF membrane was modified by blending method.Firstly,for further modification,the effects of the addition ofpolyethylene glycol?PEG?and polyvinylpyrrolidone?PVP?on hydrophilicity of PSF membrane were studied.The results showed that with the increase of PEG content,the hydrophilicity of membrane was improved and the porosity increased first and then decreased.Moreover,the water flux increased first and then decreased with the increase of PEG content,while the trend of the rejection rate of BSA was opposite.And the molecular weight of PEG also affected the performance of membrane,with the increase of molecular weight of PEG,the porosity and hydrophilicity of membrane increased.Meanwhile,the pure water flux increased while the rejection decreased.With the increase of PVP content,the contact angle of the membrane fell from 71°to 54°,the porosity increased first and then decreased.When the content of PVP was up to 4wt%,the porosity increased to 74.5%,the flux was up to 195 L/?m²·h?,and the rejection rate was down to 89%,the modified membrane has a certain anti-fouling ability.The surface groups of nano titanium dioxide?TiO₂?are mainly hydroxyl,so TiO₂ is strong hydrophilic.For further improving the hydrophilicity of membrane,building on the previous stages,PVP was chosen as additive 1,commercially available TiO₂ particles and homemade TiO₂ sol were chosen as additive 2,respectively,then the PSF membrane was prepared via immersion precipitation phase inversion process.The results showed that the addition of TiO₂ particles helps to increase the hydrophilicity of the hybrid membrane.When the content of TiO₂ particle is 1wt%,the contact angle decreased to 55°and the porosity rised to 85%,the flux reaches to the highest value,275 L/?m²·h?and the rejection was up to 95%;meanwhile,the membrane has the best anti-fouling ability.When the content of TiO₂ sol is6wt%,the contact angle decreased to 41°,the flux reached to the highest value,579 L/?m²·h?and the rejection rate was 85%.TiO₂ possesses not only strong hydrophilic,but also good antibacterial properties,and this helps to alleviate biological fouling,but TiO₂ does not possess antibacterial properties under the dark conditions.So the antibacterial particle,copper doping TiO₂ particle was prepared by the impregnation method.Then the antibacterial particle was blending with PSF to prepare membrane which has antibacterial properties under dark conditions.The content of antibacterial particle in casting solution was 1wt%.The prepared membrane has two antibacterial mechanisms—photocatalytic antibacterial mechanism and copper ion contact antibacterial mechanism.When the doping ratio of Cu²⁺/TiO₂ was 1wt%,the modified membranes exhibited the separation performance with pure water flux of 335.65 L/?m²·h?and BSA rejection rate of 85%.Moreover,through the film indiscrete method,under the UV irradiation,the antibacterial rate was 93.5%;while under the dark,the antibacterial rate was53.2%.and the shake flask method,the antibacterial rate was 71%.