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Synergistic effect of carboxylated-MWCNTs on the performance of acrylic acid UV-grafted polyamide nanofiltration membranes
摘要： Surface modification of a commercial polyamide nanofiltration membrane was achieved by UV induced graft polymerization of acrylic acid and incorporation of carboxylated-MWCNTs (COOH-MWCNTs). The grafting process was done under different monomer concentrations and UV exposure times. The modified membranes were characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle and zeta-potential analysis, and cross-flow filtration experiments. Changes in the surface hydrophilicity, negative charge and roughness of the modified membranes improved their permeability and fouling resistance significantly. The membrane grafted with 50 g/L acrylic acid under 5 min UV exposure showed the best filtration performance including pure water flux of 38.8 L/m2 h, salt rejections of 97.43% (Na2SO4) and 93.4% (NaCl), and flux recovery ratio (FRR) of 80.2% during bovine serum albumin (BSA) filtration. After optimizing grafting condition, different amounts of COOH-MWCNTs were dispersed in the monomer solution for embedding in the grafting layer. By adding 0.2 wt% COOH-MWCNTs to the grafting layer, a water flux improvement of around 30% was observed. But, excess loading of the COOH-MWCNTs led to compaction of the grafting layer and made it inflexible and subsequently, reduced the hydrophilicity and permeability of the membrane. Fouling tests with BSA aqueous solution showed that antifouling ability of the modified membranes was remarkably improved at all concentrations of the COOH-MWCNTs. Furthermore, salt rejection results displayed that simultaneous surface modification through grafting and COOH-MWCNTs embedding could effectively improve the nanofiltration performance of the membranes in the term of permeability, desalination and fouling resistance.
关键词： Acrylic acid,Nanofiltration,Antifouling,Surface modification,Multiwalled carbon nanotube,Grafting
更新于2025-09-23 15:23:52
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Determination of parvovirus retention profiles in virus filter membranes using laser scanning microscopy
摘要： Virus filtration is a highly effective method in the downstream processing of biotherapeutic products to provide effective removal of potential infectious agents based on a size exclusion mechanism. The direct visualization of viruses retained inside the filter membrane represents a valuable tool to get a deeper understanding of the filtration process and to explain observations of virus breakthrough under particular operating conditions. Parvoviruses, which are used as worst-case models in validation studies, were purified and labeled with fluorescent dyes to detect their retention pattern inside the filter membrane using laser scanning microscopy. Critical factors influencing the reproducibility and accuracy of the approach were identified and optimized. The retention profiles revealed detectable differences between viruses, suggesting that the use of bacteriophages or nanoparticles as surrogates is limited in their applicability to accurately predict the behavior of parvoviruses in filter membranes. The established method enables a direct and quantitative analysis of the virus retention profile, adding a valuable tool to the conventional measurement of the viral load reduction to better understand the mechanism underlying the removal of viruses during nanofiltration of biotherapeutic products.
关键词： Parvovirus retention profile,Virus filtration,Nanofiltration,Laser scanning microscopy,Filter membrane
更新于2025-09-23 15:19:57
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Counterion‐Switched Reversibly Hydrophilic and Hydrophobic TiO <sub/>2</sub> ‐Incorporated Layer‐By‐Layer Self‐Assembled Membrane for Nanofiltration
摘要： The manipulation of surface wettability has been regarded as an efficient strategy to improve the membrane performances. Herein, the counterion-switched reversibly hydrophilic and hydrophobic surface of TiO2-loaded polyelectrolyte membrane are prepared by layer-by-layer assembly of poly(sodium 4-styrene sulfonate) (PSS) and poly(diallydimethyl-ammoniumchloride (PDDA) containing TiO2@PDDA nanoparticles (NPs) on the hydrolyzed polyacrylonitrile (PAN) substrate membrane. The obtained polyelectrolyte multilayer (PEM) membranes [PEM-TiO2]4.5+X? (X? = Cl?, PFO? [perfluorooctanoate] etc.) show different hydrophilicity and hydrophobicity with various counterions. The integration of TiO2 NPs obviously improves the wettability and nanofiltration (NF) performance of PEM membrane for (non)aqueous system of dyes (crystal violet, eriochrome black T) with a high recyclability. The highly hydrophilic [PEM-TiO2]4.5+Cl? (water contact angle [WCA]: 13.2 ± 1.8°) and hydrophobic [PEM-TiO2]4.5+PFO? (WCA: 115.4 ± 2.3°) can be reversibly switched via counterion exchange between Cl? and PFO?, verifying the surface with a reversible hydrophilic–hydrophobic transformation. For such membranes, the morphology, wettability, and NF performance rely on the loading of TiO2@PDDA NPs and surface counterion. Meanwhile, the motion and interaction of water or ethanol in the hydrophilic or hydrophobic membrane are revealed by low-field nuclear magnetic resonance. This work provides a facile and rapid approach to fabricate smart and tunable wetting surface for potential utilization in (non)aqueous NF separation.
关键词： (non)aqueous nanofiltration,TiO2-incoporated polyelectrolyte multilayer membranes,counterion-switched surfaces,LbL self-assembly,reversible wettability
更新于2025-09-19 17:13:59