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A high-density and uniform network-like antibacterial poly(methacryloxyethyl benzyl dimethyl ammonium chloride) (PDMAE-BC) layer was covalently constructed onto polyethylene (PE) hollow fiber membrane surface in a module scale via long-distance and dynamic low-temperature (LDDLT) plasma flow irradiation and subsequent graft polymerization. After the stepwise construction using this surface plasma chemical engineering method, the hydrophilicity of membrane surface was enhanced greatly due to implantation of numerous oxygen-containing groups. Meanwhile, the surface microstructures and chemical composition distributions were more uniform along with the axial distance from the module inlet and no significant damage/etching in membrane surface was observed. And even more prominent, the obtained PDMAE-BC membrane module can effectively destroy and/or inhibit bacteria by antibacterial layer, thereby preventing the formation of biofilms. It not only exhibited a high antibacterial activity against Gram-negative Escherichia coli , but also had an antifouling property, an increased water flux and an easy-cleanability. The antibacterial efficacy reached about 92.4% in the membrane module with only 10 PE–PDMAE-BC fibers and can be further improved by increasing the fiber packing density. In the long-term running, both original and PDMAE-BC membrane modules showed a 100% rejection ratio for E. coli . Moreover, the PE–PDMAE-BC membrane module can endure general water rinsing with little loss of antibacterial efficacy and exhibited an excellent antibacterial stability. This PE–PDMAE-BC membrane module should prove useful in actual water (mainly drinking water and wastewater) treatment. [ABSTRACT FROM AUTHOR]

The modification of PE hollow fibers in a module scale was carried out by long-distance and dynamic low-temperature (LDDLT) plasma flow, which is an environment-friendly surface chemical engineering method. For the module with a plasma inlet diameter of 15 mm, contact angle variations along with fiber axial distance from plasma inlet revealed that the effective modification distance by LDDLT plasma flow was easily scaled up to about 80 cm for purpose of industrial applications. The plasma-treated membrane module (PTMM) exhibited not only good chemical resistance in various solutions but also excellent antifouling property and hydrophilic stability. Moreover, the PTMM, which was dried at 25 °C in vacuum after each filtration cycle, could still maintain high hydrophilicity after 7 water filtration cycles and storing over 90 days. Its average contact angle recovered by only 7°, and the steady water flux was about 30 L m −2 h −1 , far higher than the untreated ones. [ABSTRACT FROM AUTHOR]

Abstract: Long-distance and dynamic Ar low-temperature plasma (LDDLTP) flow pretreatment and subsequent acrylic acid (AA) grafting in aqueous solutions were developed to prepare completely hydrophilic electrospun polypropylene fibril (PPF) membranes. The investigation primarily focused on the penetrating grafts and effects of plasma conditions on the grafting. Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy, X-ray photoelectron (XPS) spectroscopy, and scanning electron microscopy (SEM) analyses were employed to characterize the chemical and morphological changes on the surface and cross-sections of the membranes. Improvements in membrane hydrophilicity and anti-fouling were characterized by measuring water contact angle (WCA), bovine serum albumin (BSA) adsorption, and water permeation. FTIR-ATR spectra of two grafted membranes irradiated in a stack showed specific absorbance peaks of carbonyl groups on three of the surfaces, but not on the downstream surface of the second membrane. The XPS and WCA analyses revealed that the active species in the LDDLTP flow can not only penetrate through the top PPF membrane but also irradiate a significant part of the second membrane. The penetration grafting modifications to the PPF membranes by the LDDLTP made the water droplet to penetrate deeply into the bulk and completely wet the whole membrane, increased water flux from 732 to 1763kgm−2 h−1 at 20°C and 0.03MPa, and reduced BSA adsorption fouling by 67% at pH 7.4. These results indicate that the controllable modifications of membranes in a module scale are possible by applying a LDDLTP. [Copyright &y& Elsevier]

Polymeric membranes have gained an immense importance for the pervaporation (PV) of biofuels. The PV performance is influenced by several complex elements and significant understanding is empirically fairly difficult. Furthermore, it is essential to specify membrane swelling in different solvents prior to the PV. A molecular dynamics simulation protocol was applied to examine the swelling of cross-linked PDMS membranes in 1-butanol, ethanol, acetone, and water, the dissolution of organic molecule in dilute aqueous solution in PDMS, the PV through these swollen membranes and dissolution rate of guest molecules in membranes. The agglomeration effects of water as well as organic molecules inside cross-linked PDMS membrane during sorption and diffusion processes were also investigated. The effects of predicted cross-linked PDMS on separation performance of membranes, interactions of the guest molecules on the swelling degree and diffusion coefficients follow the experimental trend. The predicted dissolution and diffusion, the diffusion selectivity and mean square displacement of different agglomerated forms of water and alcohol molecules through cross-linked membrane fairly matches the reported experimental results. Moreover, their reliability on the interaction between solvent and polymer, void size distribution and temperature were investigated. The micro level insights into the swelling of cross-linked polymer membranes, dissolution and diffusion of organic molecules and understanding of mass transfer were provided by simulation, which are valuable for making new membranes for high PV performance. Image 1 • A method was proposed for constructing a cross-linking PDMS model by Polymatic code. • MD simulation for the first time aiming the swelling of PDMS in 4 kinds of solvents. • Aggregates of water in PDMS contain a chain like structure of 2–3 molecules. • Dissolution selectivity of 5 wt% ABE binary aqueous solution is 74.5, 69.1, and 41.6. • An understanding of the factors affecting guest molecule dissolution and diffusion. [ABSTRACT FROM AUTHOR]

Polymeric membrane separations have been used for hydrocarbon recovery in some polyolefin plants due to the low energy consumption and easy operation, but the relatively low separation factor and hydrocarbon permeance block their ways to popularization. In this study, membranes with high propylene permeance and sufficient separation factor for propylene/nitrogen separation were prepared by direct incorporating 2-methylimidazole (MIM) into polydimethylsiloxane (PDMS), which manifested simultaneous promotion of separation factor and propylene permeance. Interestingly, MIM simultaneously acted in promoting the crosslinking process of PDMS and tetraethyl orthosilicate. A series of tests and characterizations were conducted to investigate the microstructure, morphology, thermal property, and mass transfer property of the membranes. The gas separation performance of the MIM-incorporated PDMS membrane with a separation factor of 20.2 and propylene permeance of 440.9 GPU outperformed many other propylene-selective membranes reported in the literature. Molecular dynamics simulations revealed that MIM had a preferential affinity for propylene rather than nitrogen, which was similar to PDMS, but the propylene-affinity of MIM was significantly higher than that of PDMS, accounting for the promoted separation of propylene/nitrogen upon the incorporation of MIM. The MIM-incorporated PDMS membranes with readily available, cheap materials and straightforward manufacturing procedures should be a promising alternative for hydrocarbon recovery. It is also enlightening for the study and design of membrane materials for gas separation. [Display omitted] • 2-Methylimidazole (MIM) was directly incorporated into PDMS membranes. • MIM accelerated the crosslinking reaction of PDMS prepolymer. • Separation factor and permeance of C 3 H 6 were simultaneously promoted by MIM. • MD simulation reveals MIM has a higher preferential propylene-affinity than PDMS. [ABSTRACT FROM AUTHOR]

Catalytically active membranes are the core components of the membrane reactors. Polysulfone (PSF) grafted with ionic liquids (ILs), PSF-DG-ILs, was prepared via introducing chloromethyl group into benzene ring of PSF, then grafting ILs, imidazolyl acid ILs ([(CH 2) 3 SO 3 HVIm]HSO 4), by chemical bonding. Then PSF-DG-ILs membranes were prepared by non-solvent induced phase separation technique for hydrolysis of inulin. The effects of coagulation bath, grafting degree, and various dope blending on structure, physico-chemical characters, and catalytic performance of membranes were evaluated. And results revealed that catalytic performance could be efficiently enhanced by choosing ethanol as coagulation compared with ethyl acetate, which was mainly attributed to surface segregation. Membrane mechanical strength decreased with the enhancing ILs grafting degree, while the catalytic performance increased. However, PSF-DG-ILs with high degree of ILs grafting lost its membrane-forming property. The mechanical and catalytic properties of the membrane were synergistically enhanced by blending PSF-DG-ILs polymers with high and low ILs grafting degree, then the resulting membranes broke the trade-off effect between mechanical strength and catalytic ability. Specifically, membrane fabricated by mixing the polymers with ILs grafting degree of 0.31 and 0.59 integrates optimized mechanical property and catalysis performance. The strength and strain of this blending membrane are 3.17 MPa and 14.10%. The average pore size and porosity are 215.5 nm and 46.2%. The yield of inulin hydrolysis can reach 88.22% with 20 wt% concentration of inulin at 75 °C using a flux of 23.4 L/(m2·h). Therefore, the PSF-DG-ILs membrane displayed promising potential for the application in biomass conversion. Image 1 • Novel designed PSF catalytic membranes grafted with ionic liquid were fabricated. • Strategy by blending polymers with high and low ILs grafting degree was proposed. • Membrane broke trade-off effect between mechanical strength and catalytic ability. • Membrane exhibited efficient catalytic performance and satisfactory stability. [ABSTRACT FROM AUTHOR]