Search

Abstract Different from the typical interfacial polymerization for nanofiltration membrane fabrication, we proposed a novel method to prepare charged nanofiltration membrane via rapid immersion thermal annealing process with the ultrafiltration membrane, which was prepared from the amphiphilic copolymer, poly(vinyl chloride) -g- poly(2-(dimethylamino)ethyl methacrylate) (PVC -g- PDMA) via non-solvent induced phase separation. The pore structures and chemical properties of the membranes, and annealing conditions including the media where the membrane was annealed, annealing temperature and time, were investigated in detail. It is found that the porous separation layer was collapsed to be a stable, defect-free, and smooth film as the dense separation layer of nanofiltration membrane when it was annealed in n -heptane above its glass transition temperature (T g) for only 1 min while the pore size cutoff was tailored from 20 nm to 2 nm. Salt rejections were in the order of MgCl 2 > NaCl > MgSO 4 > Na 2 SO 4 at neutral condition due to Donnan repulsion, indicating a typical positively charged nanofiltration membrane. Overall, this rapid immersion thermal annealing process provides a facile and effective strategy to tailor ultrafiltration membrane toward nanofiltration applications for amphiphilic copolymer based membranes. Graphical abstract fx1 Highlights • NF membrane was formed rapidly via thermal annealing from ultrafiltration membrane. • Pore size of NF membrane could be tailored by the annealing condition. • The positively charged NF membranes showed high divalent cations rejection and water permeace. • Outstanding adhesive strength between the supports and the separation layer was attained. [ABSTRACT FROM AUTHOR]

Novel antifouling and chlorine-resistant ultrafiltration membranes were successfully fabricated using poly(vinyl chloride-co-acrylonitrile-co-sodium 4-styrenesulfonate) (PVC-PAN-PSS), a novel poly(vinyl chloride)-based copolymer, via a non-solvent induced phase separation (NIPS) method. Quartz crystal microbalance data revealed reduced levels of bovine serum albumin (BSA) adsorption on PVC-PAN-PSS films when compared to those of pure poly(vinyl chloride) and polyacrylonitrile films. The morphologies, chemical compositions, surface roughness and hydrophilicity of the membrane surfaces were characterized by field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle goniometer, respectively. The hydrophilicity and antifouling properties of the membranes were clearly shown to increase with increasing level of poly(sodium 4-styrene-sulfonate) (PSS) in the copolymer; the membrane with 2 wt% PSS exhibited the best antifouling properties, namely ~99% of flux recovery ratio for humic acid (1.0 g L −1 ). Furthermore, the pore structures and antifouling properties of the PVC-PAN-PSS ultrafiltration membranes were maintained after soaking in 1000 ppm sodium hypochlorite for 168 h, while common membrane additives such as methacryloyloxyethylphosphorylcholine-co-poly(propylene glycol) methacrylate and Pluronic ® F-127 were rapidly degraded in this oxidizing environment. PVC-PAN-PSS is expected to be a promising ultrafiltration membrane material with both superior antifouling properties and excellent chlorine resistance. [ABSTRACT FROM AUTHOR]

Composite ultrafiltration membranes were successfully fabricated by blending a nonionic surfactant and inorganic nanoparticles via a nonsolvent‐induced phase separation (NIPS) method. Brij35 was used as the nonionic surfactant and silica (SiO2) nanoparticles from rice husk ash, a low cost and widely available material, were used as the inorganic nanoparticles. The synergetic effect of both additives was used to tailor the membrane structure and properties because the selected additives showed completely different or, in some cases, the opposite effect on the membrane properties and structure. The combined effects of Brij and SiO2 resulted in a membrane with a noticeable improvement in membrane overall performance including pure water permeability, hydrophilicity, antifouling properties, long‐term stability, tensile strength, on the cost of a slight decrease in membrane elongation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47737. [ABSTRACT FROM AUTHOR]

• Positively charged tight ultrafiltration (PCTUF) membrane was fabricated facilely with amphiphilic polymer. • The PCTUF membranes possessed a positively charged surface and 3.27 nm charged channel. • Trace heavy metal cations could be removed efficiently by PCTUF membrane. • Outstanding perm-selectivity of the PCTUF membrane could outperform the ever-reported membranes. The development of highly efficient membranes technology using low-pressure driven filtration process, is one of the principal challenges in the wastewater treatment field, especially those aimed at the removal of trace heavy metals. In this work, a novel positively charged tight ultrafiltration (PCTUF) membrane was developed to remove heavy metal cations (Mn2+, Co2+, Ni2+, Zn2+ and Cd2+) from contaminated waters via electrostatic repulsion mechanism. The PCTUF membrane was fabricated from a new polymer with poly (vinyl chloride co dimethylaminoethyl methacrylate), P (VC- co -DMA) via a nonsolvent induce phase separation (NIPS) process and following facile surface quaternization. The quaternization conditions, the pore structures and chemical properties of the membranes were investigated in detail. The optimally quaternized membrane possessed a positively charged surface and 3.27 nm charged channel with the water permeability of 84 L m−2 h−1 bar−1. The rejections of heavy metal cations surpassed 95% for feed solutions containing 10 ppm heavy metal. Moreover, the influences of feed concentrations and the operating condition with pressure and pH on the membrane performances were also investigated. The results revealed that the prepared PCTUF membrane with its high perm-selectivity performance provides a worthy reference for highly efficient removal of heavy metal cations. [ABSTRACT FROM AUTHOR]

To improve the permeability and antifouling properties of polyvinyl chloride (PVC) ultrafiltration (UF) membrane, amphiphilic sulfonated polysulfone (SPSF) was introduced into PVC matrix. Three types of PVC/SPSF blend membranes containing different SPSF with the sulfonation degree (SD) of 20%, 30%, and 50% were fabricated by non-solvent induced phase separation (NIPS) process. The excellent compatibility between PVC and SPSF was confirmed by differential scanning calorimetry (DSC). Surface chemical compositions, morphology, roughness, charge, hydrophilicity, permeability and antifouling properties of the pristine PVC membrane and the PVC/SPSF blend membranes were systematically compared and characterized. Due to the improved hydrophilicity and endowed negative charge, the blend membrane showed high water permeability (i.e. 880 L m−2h−1 bar−1), high bovine serum albumin (BSA) rejection (i.e. 95.7%), and high flux recovery ratio (i.e. 96%), which outperformed ever reported and commercialized PVC membranes. Furthermore, the permeability and rejection properties of PVC/SPSF UF membranes were maintained after soaking in acidic and alkaline solutions for 30 days, indicating their outstanding acid and alkali tolerance. Therefore, SPSF was expected as a potential versatile modifier for fabricating high performance UF membranes. [ABSTRACT FROM AUTHOR]