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Tao Wu, Zongman Zhang, Ding Zhai, Yang Liu, Qingguo Liu, Lixin Xue, Congjie Gao
A ternary nanocomposite consisting of N-doped graphene (NGR)/TiO₂/activated carbon (NGRT@AC) was prepared, and the components' synergetic effect on dye degradation was investigated after deposition on the surface of a polysulfone membrane (PSF). As far as we know, this ternary composite catalyst has never previously been used to degrade dyes nor been used as a functional layer for separation membranes. The surface morphology and structure of the as-prepared membranes were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS)...
January 15, 2019: Membranes
Alexander Dhaliwal, Adree Khondker, Richard Alsop, Maikel C Rheinstädter
The physical effects of small sugars on membranes have been studied for decades, primarily because of their membrane stabilization in cold or dehydrated environments. We studied the effects of up to 20 mol% glucose in bilayers made of 1,2-dimyristoyl- sn -glycero-3-phosphocholine (DMPC) at low hydration by combining X-ray diffraction and Molecular Dynamics (MD) simulations. In agreement with previous studies, we observe membrane thinning at low and membrane thickening at high sugar concentrations. Glucose was found to preferentially localize to the outer head region of phospholipid bilayers at all concentrations, and partitioning of sugar in the membranes was found to monotonically increase with increasing sugar concentration...
January 15, 2019: Membranes
Alexios-Spyridon Kyriakides, Spyros Voutetakis, Simira Papadopoulou, Panos Seferlis
This work focuses on the development and implementation of an integrated process design and control framework for a membrane-based hydrogen production system based on low temperature methane steam reforming. Several alternative flowsheet configurations consisted of either integrated membrane reactor modules or successive reactor and membrane separation modules are designed and assessed by considering economic and controller dynamic performance criteria simultaneously. The design problem is expressed as a non-linear dynamic optimization problem incorporating a nonlinear dynamic model for the process system and a linear model predictive controller aiming to maintain the process targets despite the effect of disturbances...
January 15, 2019: Membranes
Xenia Nebavskaya, Veronika Sarapulova, Dmitrii Butylskii, Christian Larchet, Natalia Pismenskaya
Coating ion exchange membranes with polyelectrolyte has been proven to be a cheap way to reduce concentration polarization and increase limiting current (for polyelectrolytes carrying fixed groups of the same sign of charge with respect to the membrane bulk), to create high monovalent selectivity, and to add the function of H⁺/OH- ions generation (for polyelectrolytes bearing fixed groups of the opposite sign of charge with respect to the membrane bulk). In the latter case, the balance between the counterion transport and the H⁺/OH- ions generation is affected by parameters of the substrate and the modifying layer...
January 11, 2019: Membranes
Erick Ramírez-Cedillo, Wendy Ortega-Lara, María R Rocha-Pizaña, Janet A Gutierrez-Uribe, Alex Elías-Zúñiga, Ciro A Rodríguez
Biocompatible and biodegradable membrane treatments for regeneration of bone are nowadays a promising solution in the medical field. Bioresorbable polymers are extensively used in membrane elaboration, where polycaprolactone (PCL) is used as base polymer. The goal of this work was to improve electrospun membranes' biocompatibility and antibacterial properties by adding micro- and nanoparticles such as Ag, TiO₂ and Na₂Ti₆O13 . Micro/nanofiber morphologies of the obtained membranes were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and a tensile test...
January 10, 2019: Membranes
Qing-Kun Zhong, Ze-Yin Wu, Ya-Qi Qin, Zhang Hu, Si-Dong Li, Zi-Ming Yang, Pu-Wang Li
In this study, the porous composite films of carboxymethyl chitosan/alginate/tranexamic acid were fabricated, with calcium chloride as the crosslinking agent and glycerin as a plasticizer. The composite films were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The properties of the composite films, including water absorption, air permeability, and cumulative release rate, were tested. In addition, their hemostatic performance was evaluated. The results showed that the appearance of the films with good adhesion was smooth and porous...
January 8, 2019: Membranes
Giuseppe Genduso, Bader S Ghanem, Ingo Pinnau
The nonideal behavior of polymeric membranes during separation of gas mixtures can be quantified via the solution-diffusion theory from experimental mixed-gas solubility and permeability coefficients. In this study, CO₂-CH₄ mixtures were sorbed at 35 °C in 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA)-m-phenylenediamine (mPDA)-a polyimide of remarkable performance. The existence of a linear trend for all data of mixed-gas CO₂ versus CH₄ solubility coefficients-regardless of mixture concentration-was observed for 6FDA-mPDA and other polymeric films; the slope of this trend was identified as the ratio of gas solubilities at infinite dilution...
January 8, 2019: Membranes
Alsu I Akhmetshina, Nail R Yanbikov, Artem A Atlaskin, Maxim M Trubyanov, Amal Mechergui, Ksenia V Otvagina, Evgeny N Razov, Alla E Mochalova, Ilya V Vorotyntsev
Nowadays, the imidazolium-based ionic liquids containing acetate counter-ions are attracting much attention as both highly selective absorbents of the acidic gases and CO₂ carriers in the supported ionic liquid membranes. In this regard, the investigation of the gas transport properties of such membranes may be appropriate for better understanding of various factors affecting the separation performance and the selection of the optimal operating conditions. In this work, we have tested CH₄, CO₂ and H₂S permeability across the supported ionic liquid membranes impregnated by 1-butyl-3-methylimidazolium acetate (bmim[OAc]) with the following determination of the ideal selectivity in order to compare the facilitated transport membrane performance with the supported ionic liquid membrane (SILM) that provides solution-diffusion mechanism, namely, containing 1-butyl-3-methylimidazolium tetrafluoroborate (bmim[BF₄])...
January 5, 2019: Membranes
Eleonora Ricci, Maria Grazia De Angelis
In an effort to reduce the experimental tests required to characterize the mixed-gas solubility and solubility-selectivity of materials for membrane separation processes, there is a need for reliable models which involve a minimum number of adjustable parameters. In this work, the ability of the Dual Mode Sorption (DMS) model to represent the sorption of CO₂/CH₄ mixtures in three high free volume glassy polymers, poly(trimethylsilyl propyne) (PTMSP), the first reported polymer of intrinsic microporosity (PIM-1) and tetrazole-modified PIM-1 (TZ-PIM), was tested...
January 4, 2019: Membranes
Nuha Awang, Juhana Jaafar, Ahmad Fauzi Ismail, Mohd Hafiz Dzarfan Othman, Mukhlis A Rahman
One of the main problems in direct methanol fuel cell (DMFC) application is methanol crossover. In order to solve the problem, an exfoliated void-free electrospun Sulfonated Poly(Ether Ether Ketone) (SPEEK)/cloisite nanocomposite membrane was developed. The membrane was prepared by immersing electrospun SPEEK/cloisite fiber mats onto incomplete solidified SPEEK polymer matrix. A well dispersed and reduction size of cloisite particles that ranges from 0.29⁻0.39 µm was observed by using Scanning Electron Microscopy Analysis (SEM) and Atomic Force Microscope (AFM)...
January 2, 2019: Membranes
Shouhai Zhang, Shanshan Guan, Chengde Liu, Zhenlin Wang, Danhui Wang, Xigao Jian
This paper discusses the effect of the chemical structure of sulfonated poly(aryl ether sulfone) on the performance of composite nanofiltration membranes. The composite nanofiltration membranes were fabricated by coating sulfonated poly(aryl ether sulfone) solution onto the top surface of poly(phthalazinone ether sulfone ketone) support membranes. Three kinds of sulfonated poly(aryl ether sulfone)s with different amounts of phthalazinone moieties, namely, sulfonated poly(phthalazinone ether sulfone) (SPPES), sulfonated poly(phthalazinone biphenyl ether sulfone) (SPPBES), and sulfonated poly(phthalazinone hydroquinone ether sulfone)s (SPPHES), were used as coating materials...
January 2, 2019: Membranes
Li Zhu, Kadalipura Puttaswamy Rakesh, Man Xu, Yingchao Dong
Highly efficient drinking water purification is still an important challenge for membrane techniques where high flux, high rejection, and low fouling are highly emphasized. In the present work, a porous network surface with carbon nanotubes (CNTs) was in situ constructed on hierarchically-structured mullite ceramic membranes. Interestingly, such a composite structure was demonstrated to effectively remove bacteria from drinking water with a highly stable long-term flux. After membrane structure characterizations, separation performance, such as flux and rejection, was assessed by the purification of bacteria-contaminated drinking water...
January 2, 2019: Membranes
Mitsuru Higa, Yuriko Kakihana, Takehiro Sugimoto, Kakuya Toyota
Hollow fiber type cation-exchange (C-HF) membranes and hollow fiber type anion-exchange (A-HF) membranes were prepared from poly (vinyl alcohol) (PVA)-based copolymer with cation-exchange groups and by blending PVA and polycation, respectively, by a gel fiber spinning method. In order to control the water content of the hollow fiber membranes, the membranes were cross-linked physically by annealing, and then cross-linked chemically by using glutaraldehyde (GA) solutions at various GA concentrations. The outer diameter of C-HF and A-HF membranes were ca...
January 2, 2019: Membranes
Javier M Ochando-Pulido, Antonio Martínez-Férez, Marco Stoller
Dynamic membrane system behaviour must be adequately addressed to avoid process unfeasibility. The lack of proper analysis will mean relying on erroneous permeate flux values in the system design, which will lead to quick and/or steady high fouling rates. In this paper, the authors present additional data supporting the boundary flux theory as a helpful tool for membrane engineers to carefully avoid process failures. By fitting the dynamic permeate flux data to the boundary flux model, it was possible to calculate the β fouling index for the three selected membranes (one nanofiltration (NF) and two reverse osmosis (RO) ones)...
December 26, 2018: Membranes
Haoli Zhou, Wanqin Jin
Microporous polymer membranes have been widely studied because of their excellent separation performance. Among them, polymers of intrinsic micro-porosity (PIMs) have been regarded as a potential next-generation membrane material for their ultra-permeable characteristics and their solution-processing ability. Therefore, many reviews have been reported on gas separation and monomers for the preparation of PIMs. This review aims to provide an overview of the structure-solubility property. Different structures such as non-network and network macromolecular structure made of different monomers have been reviewed...
December 26, 2018: Membranes
Simon Gustafsson, Frank Westermann, Tobias Hanrieder, Laura Jung, Horst Ruppach, Albert Mihranyan
Pore-size distribution (PSD) is the most critical parameter for size-exclusion virus removal filters. Yet, different dry- and wet-state porometry methods yield different pore-size values. The goal of this work is to conduct comparative analysis of nitrogen gas sorption (NGSP), liquid-liquid and cryoporometry with differential scanning calorimetry (CP-DSC) methods with respect to characterization of regular and cross-linked virus removal filter paper based on cellulose nanofibers, i.e. the mille-feuille filter...
December 20, 2018: Membranes
Lin Li, Ruisong Xu, Chengwen Song, Bing Zhang, Qingling Liu, Tonghua Wang
Carbon molecular sieve (CMS) membranes are novel materials derived from the pyrolysis of the polymeric precursors and have a well-developed ultra-microporous structure that can separate small gas pairs with minor difference in diameter, and thus exhibit higher gas permeability and selectivity than polymeric membranes. However, the gas permeability for traditional pure CMS membranes now cannot satisfy the requirements of commercial applications due to their disordered pore structure and high gas molecular diffusion resistance...
December 17, 2018: Membranes
Shoichi Doi, Maki Kinoshita, Masahiro Yasukawa, Mitsuru Higa
Performance of anion exchange membranes (AEMs), including polyvinyl chloride (PVC) as backing and binder, decreases during a repetitive cleaning-in-place (CIP) treatment using alkali. In this study, we have systematically performed two optical analyses, relative total visible (VIS) reflectance and handheld X-ray fluorescence (XRF), for alkali-attacked commercially available AEM (Neosepta® AMX, Tokyo, Japan) with different NaOH immersion conditions (0⁻1.0 M NaOH at 40⁻80 °C for 0⁻168 h). The VIS reflectance and XRF data were then compared with the electrical and mechanical performances (i...
December 14, 2018: Membranes
Elsa Lasseuguette, Richard Malpass-Evans, Mariolino Carta, Neil B McKeown, Maria-Chiara Ferrari
Gas transport properties of PIM-EA(H₂)-TB, a microporous Tröger's base polymer, were systematically studied over a range of pressure and temperature. Permeability coefficients of pure CO₂, N₂, CH₄ and H₂ were determined for upstream pressures up to 20 bar and temperatures up to 200 °C. PIM-EA(H₂)-TB exhibited high permeability coefficients in absence of plasticization phenomena. The permeability coefficient of N₂, CH₄ and H₂ increased with increasing temperature while CO2 permeability decreased with increasing temperature as expected for a glassy polymer...
December 14, 2018: Membranes
Abdul Latif Ahmad, Jayasree Sugumaran, Noor Fazliani Shoparwe
In this study, the antifouling properties of polyethersulfone (PES) membranes blended with different amounts of ZnO nanoparticles and a fixed ratio of N-methyl-2-pyrrolidone (NMP)-acetone mixture as a solvent were investigated. The properties and performance of the fabricated membranes were examined in terms of hydrophilicity, porosity, pore size, surface and cross-section image using scanning electron microscopy (SEM), surface roughness using atomic force microscopy (AFM), pure water flux, and humic acid filtration...
December 14, 2018: Membranes
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