Fabrication Of Antifouling Membranes Research Articles

Surface modification of PVDF membrane by CNC/Cu-MOF-74 for enhancing antifouling property

Membrane fouling is one of the main impediments that limit the wide application of Polyvinylidene fluoride (PVDF) membrane. In this study, for the first time, we incorporated the cellulose nanocrystal (CNCs) onto Cu-MOF-74 by physical stirring and then coated the composites on the PVDF membrane to ameliorate the antifouling performance. The PVDF membrane with the addition of CNC/Cu-MOF-74 composite showed enhanced hydrophilicity compared with the pristine membrane, which significantly promoted the permeability and antifouling performance. The Bovine serum albumin (BSA) multiple-cycle antifouling results revealed that the flux recovery ratio (FRR) value (76.9 %) was much higher than that of the pristine membrane (60.8 %). The enhancement of recovery flux was correlated with the increased electrostatic repulsion and hydrophilicity of the modified membrane according to the contact angle test and Zeta-potential measurement. Meanwhile, the CNC/Cu-MOF-74 modified membrane showed improved antibacterial efficiency (96.3 % at 4 h) due to the predominant antibacterial efficacy of Cu-MOF-74. The efficiently antibacterial achievement of modified membrane was attributed to the release of Cu2+ and the generation of •OH. This study proposed a novel modified membrane with excellent antifouling properties and provided new insights into the fabrication of antifouling membranes with outstanding performance.

Antifouling membranes with bi-continuous porous structures and high fluxes prepared by vapor-induced phase separation

Antifouling poly(ether sulfone) (PES) composite membranes with novel bi-continuous porous structures, high fluxes and hydrophilic surfaces are successfully prepared by simultaneously manipulating the migration of amphiphilic three-block polymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic® F127) to the membrane surfaces and the microstructures of membranes by vapor-induced phase separation (VIPS) method. Effects of the additive mass ratios of Pluronic® F127 to PES and VIPS process parameters, including the dissolution and vapor temperature (T), the relative humidity of vapor (RH) and the exposure time to vapor (t), on microstructures of membranes and the surface hydrophilicity of membranes are systematically investigated. When the additive mass ratio of Pluronic® F127 to PES is 100%, PES/Pluronic® F127 composite membranes with bi-continuous porous structure across the full cross-section can be easily fabricated. For the composite membranes with additive mass ratio of 100%, when t = 1 min, the water contact angles of membranes decrease remarkably when the temperature increases from T = 25 °C to T = 40 °C. For the PES/Pluronic® F127 composite membranes prepared via VIPS method with T = 25 °C, RH = 70% and t = 20 min, the water contact angle is as low as 34.5°, the water flux is as high as 236512 L m−2 h−1 bar−1 and the static adsorption amount of bovine serum albumin (BSA) is only 4.6 μg cm−2. Valuable guidance is presented in this study about the design and fabrication of antifouling membranes with high flux and hydrophilic surfaces.

Fabrication of antifouling membranes by blending poly(vinylidene fluoride) with cationic polyionic liquid

ABSTRACTMembrane fouling problem is now limiting the rapid development of membrane technology. A newly synthesized cationic polyionic liquid (PIL) [P(PEGMA‐co‐BVIm‐Br)] was blended with poly(vinylidene fluoride) (PVDF) to prepare antifouling PVDF membranes. The PVDF/P(PEGMA‐co‐BVIm‐Br) exhibited an increased surface hydrophilicity, the water contact angle was reduced from 77.8° (pristine PVDF) to 57.9°. More porous membrane structure was obtained by adding PIL into the blending polymers, as high as 478.0 L/m2·h of pure water flux was detected for the blend PVDF membrane in comparison with pristine PVDF (17.2 L/m2·h). Blending of the cationic PIL with PVDF gave a more positive surface charge than pristine PVDF membrane. Blend membranes showed very high rejection rate (99.1%) and flux recovery rate (FRR, 83.0%) to the positive bovine serum albumin (BSA), due to the electrostatic repulsion between the membrane surface and proteins. After three repeated filtration cycles of positive BSA, the blend PVDF membranes demonstrated excellent antifouling performance, the permeation flux of the membranes was recovered very well after a simple deionized water washing, and as high as 70% of FRR was obtained, the water flux was maintained at above 350 L/m2·h. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 48878.