The Experts below are selected from a list of 380319 Experts worldwide ranked by ideXlab platform
Benjamin S Hsiao - One of the best experts on this subject based on the ideXlab platform.
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high Filtration performance thin film nanofibrous composite membrane prepared by electrospraying technique and hot pressing treatment
Journal of Membrane Science, 2016Co-Authors: Lingdi Shen, Xuefen Wang, Xufeng Yu, Cheng Cheng, Chenlei Song, Benjamin S HsiaoAbstract:Abstract For conventional powder coating technology, powder coating materials were directly coated onto the target surface and then heated and cured to form a coat. Inspired by this technology, a facile route for fabrication of thin film nanofibrous composite (TFNC) membrane consisting of a nanofibrous substrate and a hydrophilic barrier layer was developed by electrospraying poly(vinyl alcohol) (PVA) nanobeads onto the electrospun polyacrylonitrile (PAN) substrate and following by hot-pressing treatment assisted by moistening absorption. Water molecules from absorbed moisture acted as “plasticizer” and could facilitate PVA melting. The moistened electrosprayed PVA nanobeads could be easily melted or softened to be pressed imperceptibly into an integrated barrier film on the supporting layer at a certain temperature. The depositing time of PVA electrospraying, moistcuring time, thermal treatment temperature and time were optimized to achieve an integrated, nonporous PVA barrier layer. The resulting barrier layer was chemically crosslinked and its Filtration performance can be finely controlled by different PVA crosslinking degree. Especially, the optimized PVA/PAN TFNC membrane possessed high ultraFiltration performance in BSA Filtration tests with Water flux 173.0 L/m 2 h and rejection above 98.0% at low feeding pressure 0.3 MPa. This work may provide a practical feasibility for Water Filtration application.
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electrospun nanofibrous membranes for high flux microFiltration
Journal of Membrane Science, 2012Co-Authors: Ran Wang, Brandon Li, Benjamin S HsiaoAbstract:Abstract Highly porous electrospun nanofibrous membranes have gained considerable interest in Water Filtration applications. To understand the effects of electrospun nanofibrous structures on the Filtration performance, a series of nanofibrous membranes with different fiber diameters, diameter distributions and membrane thicknesses were prepared and studied. The results indicate a strong correlation between the physical parameters of the membrane and the Filtration performance. For example, a thicker membrane with a smaller average fiber diameter greatly favors the formation of a smaller pore size and narrower pore size distribution, although the influence of the membrane thickness is relatively limited. Based on successful control of the total composite structure (electrospun polyacrylonitrile (PAN)/non-woven polyethylene terephthalate (PET)) containing the electrospun layer thickness of 200 ± 10 μm and a mean fiber diameter of 100 ± 20 nm, a high flux microFiltration (MF) membrane with a maximum pore size of 0.62 ± 0.03 μm and a mean pore size of 0.22 ± 0.01 μm was obtained. The PAN/PET nanofibrous MF membranes performed significantly better than the commercial MF membrane of the same mean pore size (0.22 μm), with two to three times higher flux (∼1.5 L/m2 h). The nanofibrous MF filter could maintain a very high rejection ratio of micro-particle and bacteria (LRV = 6). The results suggest that electrospun nanofibrous membranes are excellent materials for high-flux MF applications.
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Novel nanofibrous scaffolds for Water Filtration with bacteria and virus removal capability
Journal of Electron Microscopy, 2011Co-Authors: Anna Sato, Hongyang Ma, Benjamin S Hsiao, Ran Wang, Benjamin ChuAbstract:We demonstrate a new class of composite fibrous membranes, consisting of an ultra-fine cellulose nanofibrous network infused into an electrospun polyacrylonitrile (PAN) nanofibrous scaffold on a melt-blown polyethylene terephthalate (PET) non-woven substrate for Water purification. Depending on the infusion process and the ultra-fine cellulose nanofibers (UFCNs) used [e.g. modified ultra-fine cellulose nanofibers (m-UFCNs) or microcrystalline cellulose nanofibers (MCCNs)], different nanostructured scaffolds were formed as seen by electron microscopy. Membranes with UFCNs consist of an interwoven two-dimensional ultra-fine nanofibrous network that is deeply entangled with the electrospun scaffold and organized in a quasi-three-dimensional fashion, while those with MCCNs tend to locally wrap around the electrospun scaffolding nanofibers without forming a major network. Filtration tests illustrated that both membranes, while maintaining high permeation flux, exhibited excellent retention capabilities for simultaneous sieving for bacteria and adsorption for viruses.
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high flux ultraFiltration membranes based on electrospun nanofibrous pan scaffolds and chitosan coating
Polymer, 2006Co-Authors: Kyunghwan Yoon, Xuefen Wang, Dufei Fang, Benjamin S HsiaoAbstract:Abstract Conventional ultraFiltration (UF) or nanoFiltration (NF) filters for Water treatments are based on porous membranes, typically manufactured by the phase immersion method. The torturous porosity in these membranes usually results in a relatively low flux rate. In this study, we demonstrated a new type of high flux UF/NF medium based on an electrospun nanofibrous scaffold (e.g. polyacrylonitrile, PAN) coupled with a thin top layer of hydrophilic, Water-resistant, but Water-permeable coating (e.g. chitosan). Such nanofibrous composite membranes can replace the conventional porous membranes and exhibit a much higher flux rate for Water Filtration. The interconnected porosity of the non-woven nanofibrous scaffold can be controlled partially by varying the fiber diameter (from about 100 nm to a few micrometers) through the electrospinning processing. The example membrane, containing an electrospun PAN scaffold with an average diameter from 124 to 720 nm and a porosity of about 70%, together with a chitosan top layer having a thickness of about 1 μm, although not yet fully optimized, exhibited a flux rate that is an order magnitude higher than commercial NF membranes in 24 h of operation, while maintaining the same rejection efficiency (>99.9%) for oily waste-Water Filtration.
Mark D. Sobsey - One of the best experts on this subject based on the ideXlab platform.
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chitosan coagulation to improve microbial and turbidity removal by ceramic Water Filtration for household drinking Water treatment
International Journal of Environmental Research and Public Health, 2016Co-Authors: Lydia Abebe, Xinyu Chen, Mark D. SobseyAbstract:The use of porous ceramic filters is promoted globally for household Water treatment, but these filters are ineffective in removing viruses from Water. In order to increase virus removal, we combine a promising natural coagulant, chitosan, as a pretreatment for ceramic Water filters (CWFs) and evaluate the performance of this dual barrier Water treatment system. Chitosan is a non-toxic and biodegradable organic polymer derived by simple chemical treatments from chitin, a major source of which is the leftover shells of crustacean seafoods, such as shrimp, prawns, crabs, and lobsters. To determine the effectiveness of chitosan, model test Water was contaminated with Escherichia coli K011 and coliphage MS2 as a model enteric bacterium and virus, respectively. Kaolinite clay was used to model turbidity. Coagulation effectiveness of three types of modified chitosans was determine at various doses ranging from 5 to 30 mg/L, followed by flocculation and sedimentation. The pre-treated supernatant Water was then decanted into the CWF for further treatment by Filtration. There were appreciable microbial removals by chitosan HCl, acetate, and lactate pretreatment followed by CWF treatment, with mean reductions (95% CI) between 4.7 (±1.56) and 7.5 (±0.02) log10 for Escherichia coli, and between 2.8 (±0.10) and 4.5 (±1.04) log10 for MS2. Turbidity reduction with chitosan treatment and Filtration consistently resulted in turbidities < 1 NTU, which meet turbidity standards of the US EPA and guidance by the World Health Organization (WHO). According to WHO health-based microbial removal targets for household Water treatment technology, chitosan coagulation achieved health protective targets for both viruses and bacteria. Therefore, the results of this study support the use of chitosan to improve household drinking Water Filtration processes by increasing virus and bacteria reductions.
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Sustained use of a household-scale Water Filtration device in rural Cambodia
Journal of Water and Health, 2009Co-Authors: Joe Brown, S. Proum, Mark D. SobseyAbstract:The effectiveness of point-of-use Water treatment may be limited by declining use over time, particularly when Water treatment is introduced via targeted intervention programmes. In order to evaluate the long-term uptake and use of locally produced ceramic Water filters in rural Cambodia, we visited households that had received filters as part of NGO-subsidized distribution programmes over a 4 year period from 2002 to 2006. Of the more than 2,000 filters distributed, we visited 506 randomly selected households in 13 villages spanning three provinces to assess filter time in use and to collect data on factors potentially correlated with long-term use. Results indicate that filter use declined at the rate of approximately 2% per month after implementation, largely owing to breakages, and that, controlling for time since implementation, continued filter use over time was most closely positively associated with: related Water, sanitation and hygiene practices in the home; cash investment in the technology by the household; and use of surface Water as a primary drinking Water source.
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point of use household drinking Water Filtration a practical effective solution for providing sustained access to safe drinking Water in the developing world
Environmental Science & Technology, 2008Co-Authors: Mark D. Sobsey, Christine E Stauber, Joe Brown, Lisa M Casanova, Mark ElliottAbstract:The lack of safe Water creates a tremendous burden of diarrheal disease and other debilitating, life-threatening illnesses for people in the developing world. Point-of-use (POU) Water treatment technology has emerged as an approach that empowers people and communities without access to safe Water to improve Water quality by treating it in the home. Several POU technologies are available, but, except for boiling, none have achieved sustained, large-scale use. Sustained use is essential if household Water treatment technology (HWT) is to provide continued protection, but it is difficult to achieve. The most effective, widely promoted and used POU HWTs are critically examined according to specified criteria for performance and sustainability. Ceramic and biosand household Water filters are identified as most effective according to the evaluation criteria applied and as having the greatest potential to become widely used and sustainable for improving household Water quality to reduce Waterborne disease and death.
Temesgen Samuel - One of the best experts on this subject based on the ideXlab platform.
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development of antimicrobial Water Filtration hybrid material from bio source calcium carbonate and silver nanoparticles
Applied Surface Science, 2014Co-Authors: Vitus Apalangya, Vijaya K Rangari, Boniface J Tiimob, Shaik Jeelani, Temesgen SamuelAbstract:Abstract Biobased calcium carbonate and silver hybrid nanoparticles were synthesized using a simple mechanochemical milling technique. The XRD spectrum showed that the hybrid materials is composed of crystalline calcite and silver nanoparticles. The TEM results indicated that the silver nanoparticles are discrete, uncapped and well stabilized in the surface of the eggshell derived calcium carbonate particles. The silver nanoparticles are spherical in shape and 5–20 nm in size. The SEM studies indicated that the eggshells are in micron size with the silver nanoparticle embedded in their surface. The hybrid eggshell/silver nanocomposite exhibited superior inhibition of E. coli growth using the Kirby–Bauer discs diffusion assay and comparing the zone of inhibition around the filter paper disc impregnated with the hybrid particles against pristine silver nanoparticles.
Richard D Noble - One of the best experts on this subject based on the ideXlab platform.
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thin film composite bicontinuous cubic lyotropic liquid crystal polymer membranes effects of anion exchange on Water Filtration performance
Journal of Membrane Science, 2014Co-Authors: Laine M Carte, Ia R Wiesenaue, Richard D NobleAbstract:The effects of anion-exchange on the Filtration performance of thin-film composite (TFC) membranes with an active layer consisting of a nanostructured, lyotropic (i.e., surfactant) liquid crystal (LLC) polymer were investigated. These TFC LLC membranes are made by the in situ cross-linking of reactive amphiphiles (i.e., surfactants) that self-organize in the presence of glycerol into a type I bicontinuous cubic (QI) phase that contains a uniform, 3D-interconnected pore network lined with tethered cationic moieties and free mobile anions in the pores. In this study, a systematic series of experiments were performed to independently investigate how monovalent cations and anions affect transport in these TFC QI membranes. TFC QI membranes exposed to feed solutions that contain different cations (i.e., Li+(aq), Na+(aq), and K+(aq)) but have the same monovalent anion as the free mobile anion in the membrane (i.e., Br–(aq)) have a constant flux and a high rejection (>98%). When the cation is kept constant (i.e., Na+(aq)) and the anion in the feed is varied (i.e., Cl–(aq), Br–(aq), NO3(aq)–, and I–(aq)) and allowed to partially anion-exchange with the membrane, a high rejection is maintained (≥96%), but the flux significantly changes depending on the anion in the feed solution. The flux of the TFC QI membranes can also be repeatedly be cycled by contacting the membranes with different anions. Control experiments with completely anion-exchanged TFC QI membranes (i.e., with Cl–(aq), Br–(aq), NO3(aq)–, and I–(aq)) showed that the rejection of sodium salts and uncharged organic solutes was virtually the same for all of the completely anion-exchanged membranes. As a whole, these results demonstrate that the flux of these TFC QI membranes can be tuned by changing the anion with little to no change in the rejection performance. The unique performance characteristics of TFC QI membranes may offer advantages over conventional NF and RO membranes for Water purification applications or other aqueous separations.
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Water Filtration performance of a lyotropic liquid crystal polymer membrane with uniform sub 1 nm pores
Journal of Membrane Science, 2011Co-Authors: Eva S Hatakeyama, Christophe J Gabriel, Ia R Wiesenaue, Jenny L Loh, Meijua Zhou, Richard D NobleAbstract:Abstract The Water Filtration performance of a supported, nanostructured, lyotropic (i.e., surfactant) liquid crystal (LLC) polymer membrane containing uniform, sub-1-nm pores was examined in more detail using more extensive aqueous Filtration tests and a more structurally representative nanopore model. This nanoporous membrane material is based on the radical cross-linking of an ionic, LLC monomer that forms a type I bicontinuous cubic (Q I ) phase with a 3D interconnected, annulus-like, Water pore network. Previously, initial Water transport studies using a limited number of solutes demonstrated initial proof-of-concept that this LLC polymer membrane can reject small molecules based on molecular size discrimination. In this study, more comprehensive transport experiments using aqueous solutions containing a wider range of different size neutral organic molecules and salt ions were undertaken. The results of these experiments showed that the LLC polymer membrane has a rejection performance in between that of a commercial, high-performance reverse osmosis (RO) membrane (Dow SW30HR) and that of a conventional porous nanoFiltration (NF) membrane (Dow NF-270) with non-uniform pore sizes. Specifically, the LLC membrane was found to reject inorganic salt ions much better than a NF membrane, and on a level comparable to a RO membrane. It does not reject small neutral organic solutes as well as a RO membrane, but it was found to reject organic solutes better than a conventional NF membrane. Also, the organic solute rejection behavior was fitted using two different Donnan-steric pore models (DSPM) with different pore shapes (i.e., cylindrical and straight slit). It was determined that the Q I -phase LLC membrane has an effective pore radius between 0.29 nm and 0.45 nm. This modeling also suggested that the LLC nanopores are indeed uniform in size. Initial chemical stability and fouling experiments suggest this nanoporous LLC polymer membrane is also very resistant to chlorine degradation and protein fouling. This combination of properties makes this nanoporous LLC polymer a very promising membrane material for Water desalination and other NF processes.
Edward L Cussle - One of the best experts on this subject based on the ideXlab platform.
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self assembled block copolymer thin films as Water Filtration membranes
ACS Applied Materials & Interfaces, 2010Co-Authors: William A Phillip, Ando J Oneill, Marc D Rodwogi, Marc A Hillmye, Edward L CussleAbstract:Nanoporous membranes containing monodisperse pores of 24 nm diameter are fabricated using poly(styrene-b-lactide) block copolymers to template the pore structure. A 4 μm thin film of the block copolymer is cast onto a microporous membrane that provides mechanical reinforcement; by casting the copolymer film from the appropriate solvents and controlling the solvent evaporation rate, greater than 100 cm2 of a thin film with polylactide cylinders oriented perpendicular to the thin dimension is produced. Exposing the composite membrane to a dilute aqueous base selectively etches the polylactide block, producing the porous structure. The ability of these pores to reject dissolved poly(ethylene oxide) molecules of varying molecular weight matches existing theories for transport through small pores.
