排序方式: 共有87条查询结果,搜索用时 109 毫秒
41.
Y. Mansourpanah S.S. Madaeni A. Rahimpour A. Farhadian A.H. Taheri 《Journal of membrane science》2009,330(1-2):297-306
Titanium dioxide (TiO2) nanoparticles were assembled on the surface of nanofiltration blend membrane. For settling TiO2 on the membrane surface, two membrane categories were used: (i) unmodified polyethersulfone (PES)/polyimide (PI) blend membrane, and (ii) –OH functionalized PES/PI blend membrane with different concentrations of diethanolamine (DEA). These membranes were radiated by UV light after TiO2 depositing with different concentrations. 15 min immersion in colloidal suspension and 15 min UV irradiation with 160 W lamps were used for modification. The modification resulted in the formation of a photo-catalytic property with enhanced membrane hydrophilicity. The self-assembly of TiO2 nanoparticles was established through coordinance bonds with –OH functional groups on the membrane surface. A comparison between the UV irradiated TiO2 deposited blend membrane and deposited-functionalized blend membranes showed that –OH groups originate excellent adhesion of TiO2 nanoparticles on the membrane surface, increase reversible deposition, and diminish irreversible fouling. The membranes were characterized using SEM, FTIR, EDX, contact angle, cross flow filtration, and antifouling measurements. SEM images show that the presence of –OH groups on the DEA-modified membrane surface is the main parameter for extra uniformly settlement of TiO2 nanoparticles on the membrane surface. This procedure is a superior technique for modification of PES/PI nanofiltration membranes to enhance water flux and minimization membrane fouling. 相似文献
42.
Pieter Vandezande Xianfeng Li Lieven E.M. Gevers Ivo F.J. Vankelecom 《Journal of membrane science》2009,330(1-2):307-318
High throughput (HT) techniques were applied for the first time for a detailed study of parameters involved in a phase inversion process. The synthesis of integrally skinned asymmetric polyimide (Matrimid®) membranes was investigated. In spite of being one of the most important materials of reference in solvent resistant nanofiltration (SRNF), a detailed study of the phase inversion parameters for this system is still missing. Phase inversion parameters were selected both on the level of the composition of the casting solution (polymer concentration, solvent type, co-solvent/solvent weight ratio, non-solvent content) as on the level of the post-casting (evaporation time) and immersion (composition coagulation medium) conditions. The study of this extensive parameter space was conducted in a HT-fashion, in which the entire membrane preparation and testing process was miniaturized, parallellized and automated. Thanks to the availability of reliable HT techniques at all levels (i.e. preparation of polymer solutions, membrane casting and membrane testing), 145 membranes were prepared and tested (in triplicate) in the separation of the dye rose Bengal from 2-propanol within a time frame of a few months, meaning a dramatic improvement in time- and cost-efficiency. An attempt was made to link the SRNF performances of the prepared membranes and their SEM-observed morphologies more fundamentally to the phase inversion parameters through the use of Hansen solubility parameters and viscosity measurements. 相似文献
43.
Roy Chowdhury S Witte PT Blank DH Alsters PL Ten Elshof JE 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(11):3061-3066
The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous gamma-alumina membranes is reported. The recovery of Q(12)[WZn(3)(ZnW(9)O(34))(2)] (Q=[MeN(n-C(8)H(17))(3)](+)) from toluene-based media was quantitative within experimental error, while up to 97 % of Na(12)[WZn(3)(ZnW(9)O(34))(2)] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed. 相似文献
44.
In this work, m‐phenylenediamine (MPD) is used to prepare cross‐linked polyetherimide (PEI)‐based nanofiltration (NF) membrane for treatment of dye containing wastewater. The effects of dope solution composition, cross‐linking time, and dye concentration on membrane performance are investigated. Results indicate that the rejection of dye is increased with the increase of acetone concentration in the dope solution, cross‐linking time, and dye concentration. Meanwhile, membrane flux showed the opposite trend. With the aid of SEM and FTIR analysis, the cross‐linking between MPD and PEI is confirmed. The cross‐linked membrane has thicker and dense selective layer compared to the unmodified membrane. The cross‐linked NF membrane (PEI: 15 wt%; acetone: 20 wt%; cross‐linking time: 10 minutes) showed good performance in filtration of synthetic dye wastewater (Reactive Red 120, 1500 ppm) with 98% dye rejection and 0.013 L m?2 hour?1 of flux at relatively low operating pressure (60 psi). 相似文献
45.
Daniëlle Scheepers Benjamin Chatillon Kitty Nijmeijer Zandrie Borneman 《Journal of polymer science. Part A, Polymer chemistry》2021,59(12):1293-1304
Nanofiltration (NF) membrane processes are attractive to remove multivalent ions. As ion retention in NF membranes is determined by both size and charge exclusion, negatively charged membranes are required to reject negatively charged ions. Layer-by-layer assembly of alternating polycation (PC) and polyanion layers on top of a support is a versatile method to produce membranes. Especially the polyelectrolyte (PE) couple polydiallyldimethylammoniumchloride and poly(sodium-4-styrenesulfonate) (PDADMAC/PSS) is extensively investigated. This PE couple cannot form highly negatively charged membrane surfaces, due to interdiffusion and charge overcompensation of PDADMAC into the PSS layers, which limits the operational window to tailor membrane properties. We propose the use of asymmetric layer formation and show how combining two charge densities of one PC can produce negatively charged NF membranes. Starting from hollow fiber ultrafiltration supports coated with base layers of PDADMAC/PSS, they are coated with PDADMAC/PSS or poly(acrylamide-co-diallyldimethylammoniumchloride), P(AM-co-DADMAC)/PSS layers. P(AM-co-DADMAC) has a charge density of only 32% compared to 100% for PDADMAC. The particular novel membranes coated with P(AM-co-DADMAC) have a highly negatively charged surface and high permeabilities (7–19 L/[m2hbar]), with high retentions for Na2SO4 of up to 95%. These values position the developed membranes in the top range compared to commercial and other layer-by-layer membranes. 相似文献
46.
K.R. Balaji R. Hardian V.G.D. Kumar R. Viswanatha S. Kumar S. Kumar A. Singh M.S. Santosh G. Szekely 《Materials Today Chemistry》2021
Composite nanofiltration membranes offer advantages because of synergetic effects among the constituent materials’ properties. However, the sustainability of both the membrane fabrication and the raw materials has been a drawback of this energy-efficient separation technology. We report the facile fabrication of a nanocomposite membrane composed of a two-dimensional (2D) material of reduced graphene oxide (rGO) combined with a one-dimensional (1D) material of a ternary metal-based chalcogenide (NaFeS2 or NFS) using silkworm pupae protein as a natural binder. All the source materials can be derived from either nature or waste, ensuring the sustainability of the membrane and its production method. The structural characteristics of the synthesized membranes were analyzed, and the morphology of the composite membranes was studied thoroughly. Thermogravimetric analysis, differential scanning calorimetry, and nanoindentation characterizations indicated that the composite membranes were mechanically and thermally stable. The water and acetone fluxes; salt, dye, and pollutant rejections; and long-term membrane performance were evaluated using a cross-flow filtration system. Solute rejection was observed to increase (up to 98%, 94%, 95%, and 78% for Rhodamine B, 2,4-dichlorophenol, MgCl2, and NaCl, respectively) with increasing concentration of the nanomaterials in the membrane. The fine-tuning of the molecular weight cutoff from 794 to 600 g mol?1 was achieved by varying the concentration of the nanomaterials from 1 to 3 mg mL?1. Our research findings demonstrate the synergetic effects of combining 1D and 2D materials using silkworm pupae binder. The composite membrane was stable in different classes of organic solvents, including hydrocarbons, alcohols, esters, ethers, polar aprotic solvents, halogenated solvents, and ketones. This first use of natural pupae binder in constructing membrane materials paves the way toward the development of more sustainable membranes. 相似文献
47.
Inside Cover: Self‐Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra‐ to Nanofiltration (Angew. Chem. Int. Ed. 47/2015)
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48.
Ashok K. Pandey Ronald F. Childs Marcia West John N. A. Lott Brian E. McCarry James M. Dickson 《Journal of polymer science. Part A, Polymer chemistry》2001,39(6):807-820
Robust, polyelectrolyte‐filled, microporous membranes were prepared by the introduction and crosslinking of a preformed polymer within the pores of a poly(propylene) host membrane. Specifically, poly(vinylbenzyl chloride) (PVBCl) was reacted with piperazine or 1,4‐diaminobicyclo[2.2.2]octane in an N,N‐dimethylformamide (DMF) solution contained in the pores of the microporous base membrane. The remaining chloromethyl groups were reacted with an amine, such as trimethylamine, to form positively charged ammonium sites. This simple two‐step procedure gave dimensionally stable, anion‐exchange membranes in which the degree of crosslinking and the mass loading were determined by the concentration of PVBCl and crosslinker in the starting DMF solution. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes are fully characterized. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 807–820, 2001 相似文献
49.
高分子纳滤膜的研究及进展 总被引:5,自引:0,他引:5
对高分子纳滤膜的发展背景以及国内外在这一领域的研究的研究进展作了详细的介绍。 相似文献
50.