Study On The Performance Improvement Of Polyethersulfone Ultrafiltration Membrane Using Polymers And Nanomaterials

As an efficiency, energy saving, environmental friendly and molecular grade filtration technology, membrane separation is generally applied to separation, concentration, purification and refining functions. The separation membrane is the crucial component of membrane process, and it is important to develop the application of membranes with high-performance. Ultrafiltration is a major branch of membrane separation, and widely used for the industrial water treatment, pharmaceutical, food processing and living water purification and other fields. In order to obtain high-performance ultrafiltration membrane, in this work, several polymers and polyaniline nanocomposites(PANI-PVP) and titanium dioxide nanomaterials were used to improve the separation performance of polyethersulfone(PES) ultrafiltration membrane.The modified ultrafiltration membranes were prepared via immerse precipitation phase inversion method by using PES as the membrane material, N,N-Dimethylacetamide(DMAc) as the solvent, polymethylmethacrylate(PMMA), polyvinylpyrrolidone(PVP-58000), triblock copolymer(Pluronic F127) or copolymer of vinyl acetate and N-vinyl pyrrolidone(P(vp-co-va)-50000) as the polymer additives. The effects of the additive type on membrane performance were investigated. The results demonstrated that the modified memebranes using PMMA, PVP, Pluronic F127, and P(vp-co-va) as the additive showed the typical asymmetric structure. The addition of polyer additives promoted the formation of large cavity at the cross section structure of the membrane. The addition of polymer additives can enhance membrane hydrophilicity and the pure water flux.The pure water flux of PES ultrafiltration membrane was increased about 1.7-4.8 times, and BSA rejection remained at above 96.7%.Dispersion polymerization is employed for the preparation of PANI-PVP8000, PANI-PVP58000 nanocomposites. Other two titanium dioxide nanoparticles, TiO2(5-10nm) and TiO2(25nm), were also selected as the additives. The effects of these four kinds of nanomaterials on the membrane performance were analyzed and compared. The results showed that the prepared PES/PANI-PVP8000-0.5 nanocomposite membrane had a hydrophilic surface with the water contact angle of 62.5°. Both of the pure water flux of nano modified composite materials and the BSA solution flux were promoted, besides, the intercept rate of BSA could reach above 98.7%. The addition of nanoparticles also improved antifouling property of the membranes.By using the mixed additives, such as Plu/PANI-PVP58000, P(vp-co-va)/PANI-PVP58000, P(vp-co-va)/TiO2(5-10nm), and Plu/TiO2(5-10nm), the prepared modified ultrafiltration membranes showd an improvment in surface hydrophilicity and permeation flux. The PES/Plu-2.0/PANI-PVP58000-0.5 membrane had asurface contact angle of 63.1°. Under 0.20 MPa TMP, the modified membranes incorporating the mixed additive exhibited 3.4-5.0 times of pure water flux of PES membrane with BSA intercept rate of above 97.3%.