Types Of Membrane Materials Research Articles

Constructing Microporous Ion Exchange Membranes via Simple Hypercrosslinking for pH‐Neutral Aqueous Organic Redox Flow Batteries

AbstractIon exchange membranes (IEMs) play a critical role in aqueous organic redox flow batteries (AORFBs). Traditional IEMs that feature microphase‐separated microstructures are well‐developed and easily available but suffer from the conductivity/selectivity tradeoff. The emerging charged microporous polymer membranes show the potential to overcome this tradeoff, yet their commercialization is still hindered by tedious syntheses and demanding conditions. We herein combine the advantages of these two types of membrane materials via simple in situ hypercrosslinking of conventional IEMs into microporous ones. Such a concept is exemplified by the very cheap commercial quaternized polyphenylene oxide membrane. The hypercrosslinking treatment turns poor‐performance membranes into high‐performance ones, as demonstrated by the above 10‐fold selectivity enhancement and much‐improved conductivities that more than doubled. This turn is also confirmed by the effective and stable pH‐neutral AORFB with decreased membrane resistance and at least an order of magnitude lower capacity loss rate. This battery shows advantages over other reported AORFBs in terms of a low capacity loss rate (0.0017 % per cycle) at high current density. This work provides an economically feasible method for designing AORFB‐oriented membranes with microporosity.

Constructing Microporous Ion Exchange Membranes via Simple Hypercrosslinking for pH-Neutral Aqueous Organic Redox Flow Batteries.

Ion exchange membranes (IEMs) play a critical role in aqueous organic redox flow batteries (AORFBs). Traditional IEMs that feature microphase-separated microstructures are well-developed and easily available but suffer from the conductivity/selectivity tradeoff. The emerging charged microporous polymer membranes show the potential to overcome this tradeoff, yet their commercialization is still hindered by tedious syntheses and demanding conditions. We herein combine the advantages of these two types of membrane materials via simple in situ hypercrosslinking of conventional IEMs into microporous ones. Such a concept is exemplified by the very cheap commercial quaternized polyphenylene oxide membrane. The hypercrosslinking treatment turns poor-performance membranes into high-performance ones, as demonstrated by the above 10-fold selectivity enhancement and much-improved conductivities that more than doubled. This turn is also confirmed by the effective and stable pH-neutral AORFB with decreased membrane resistance and at least an order of magnitude lower capacity loss rate. This battery shows advantages over other reported AORFBs in terms of a low capacity loss rate (0.0017 % per cycle) at high current density. This work provides an economically feasible method for designing AORFB-oriented membranes with microporosity.

Analysis and comparison of the membrane-cryogenic hybrid process and multistage membrane process for pre-combustion carbon capture based on the superstructure method

The feed in pre-combustion carbon capture has a high CO2 concentration and high pressure, which gives membrane technology and membrane-based hybrid technology a strong separation driving force. Because the membrane-cryogenic hybrid method can inexpensively achieve the high CO2 purity and recovery, it offers a novel approach in addition to traditional separation methods. Nevertheless, it is uncommon to consider the combination of membrane materials and processes. Furthermore, investigations comparing multistage membrane processes with membrane-cryogenic hybrid processes under identical conditions are lacking. Therefore, this paper establishes separately the membrane-cryogenic hybrid processes and multistage membrane process by the superstructure method, which considers the number of membrane stage, membrane material type, and operating parameters simultaneously. The optimal process structures for three-stage membrane, cryogenic-membrane process, and membrane-cryogenic process are investigated and compared. The influences of membrane price and electricity price on the CO2 capture cost are also investigated. Results shows that the CO2 capture cost of cryogenic + membrane process is the lowest (11.69 $/t CO2) of the studied processes at 96 % CO2 purity and 90 % CO2 recovery. The system structure of the cryogenic + membrane process varies with CO2 purity and recovery. Electricity price has a more important impact on the CO2 capture cost than membrane price under the optimized conditions.

Microalgae cell adhesions on hydrophobic membrane substrates using quartz crystal microbalance with dissipation.

Microalgal cell adhesion and biofilm formation are affected by interactions between microalgae strains and membrane materials. Variations of surface properties of microalgae and membrane materials are expected to affect cell-membranes and cell-cell interactions and thus initial microalgal cell adhesion and biofilm formation rates. Hence, it should be possible to identify the dominant mechanisms controlling microalgal cell adhesion and biofilm formation. The effects of surface properties of three different microalgal strains and three different types of membrane materials on microalgal cell adhesion and biofilm formation were systematically investigated in real time by monitoring changes in the oscillation frequency and dissipation of the quartz crystal resonator (QCM-D). The results revealed that in general a higher surface free energy, more negative zeta potential, and higher surface roughness of membrane materials positively correlated with a larger quantity of microalgae cell deposition, while a more hydrophilic microalgae with a larger negative zeta potential preferred to attach to a more hydrophobic membrane material. The adhered microalgal layers exhibited viscoelastic properties. The relative importance of these mechanisms in controlling microalgae cell attachment and biofilm formation might vary, depending on the properties of specific microalgae species and hydrophobic membrane materials used.

The tensile strength test and result comparison of new transparent architecture membrane material STFE

ABSTRACT STFE(structural, transparent, fluorinated, envelope) membrane material is a new type of transparent architecture membrane material. Compared with general architecture membrane materials, which have the disadvantage of cannot balance strength and transparency, STFE has both high transparency and certain tensile strength. In this study, tensile strength tests were conducted on this new type of membrane material, and data obtained from different test methods, such as clamping test, winding test, and dumbbell-shaped test, were compared, and the mechanism for the differences was analyzed. The results showed that the winding-type test with smooth surface contact yielded the highest and most accurate strength data, clamping tests due to the tendency of the specimen to slip out of the clamping end, dumbbell tests due to the stress concentration effect, and winding tests with rough surface contact due to material damage caused by pressure, all reduce the measured tensile strength values. The measured tensile strength of STFE membrane material was 4241N/5 cm in the warp direction and 4335N/5 cm in the weft direction. This indicates that STFE membrane material has sufficient strength to be used in tensile membrane structures.

Surface properties of membrane materials and their role in cell adhesion and biofilm formation of microalgae

In this study, the effects of surface properties of membrane materials on microalgae cell adhesion and biofilm formation were investigated using Chlorella vulgaris and five different types of membrane materials under hydrodynamic conditions. The results suggest that the contact angle (hydrophobicity), surface free energy, and free energy of cohesion of membrane materials alone could not sufficiently elucidate the selectivity of microalgae cell adhesion and biofilm formation on membrane materials surfaces, and membrane surface roughness played a dominant role in controlling biofilm formation rate, under tested hydrodynamic conditions. A lower level of biofilm EPS production was generally associated with a larger amount of biofilm formation. The zeta potential of membrane materials could enhance initial microalgae cell adhesion and biofilm formation through salt bridging or charge neutralization mechanisms.

Current and Potential Applications of Green Membranes with Nanocellulose.

Large-scale applications of nanotechnology have been extensively studied within the last decade. By exploiting certain advantageous properties of nanomaterials, multifunctional products can be manufactured that can contribute to the improvement of everyday life. In recent years, one such material has been nanocellulose. Nanocellulose (NC) is a naturally occurring nanomaterial and a high-performance additive extracted from plant fibers. This sustainable material is characterized by a unique combination of exceptional properties, including high tensile strength, biocompatibility, and electrical conductivity. In recent studies, these unique properties of nanocellulose have been analyzed and applied to processes related to membrane technology. This article provides a review of recent synthesis methods and characterization of nanocellulose-based membranes, followed by a study of their applications on a larger scale. The article reviews successful case studies of the incorporation of nanocellulose in different types of membrane materials, as well as their utilization in water purification, desalination, gas separations/gas barriers, and antimicrobial applications, in an effort to provide an enhanced comprehension of their capabilities in commercial products.

Research progress and prospects on hydrogen separation membranes

Abstract Membrane separation technologies, with a broad application prospect in the field of hydrogen separation, are characterized by the simplicity of the devices, high energy efficiency and environmental friendliness. The performance of separation membranes is the primary factor that determines the efficiency of hydrogen separation. Therefore, the development of hydrogen separation membranes is always a research focus. This paper presents and reviews the research developments and features of organic membranes, inorganic membranes and hybrid matrix membranes for hydrogen separations. First, the characterization methods of key index parameters of membrane materials are presented. Second, the performance parameters of different types of membrane are compared. Finally, the trend of technological development of different types of membrane materials is forecast.

REGENERATION OF ULTRAFILTRATION MEMBRANES IN THE PROCESS OF SEPARATING OIL-WATER SYSTEMS

It is proposed to use a baromembrane process for the purification of spent oil-containing products. Tubular ultrafluorescence polymer membranes with an active layer of fluoroplast with diatomite additives and ceramic membranes based on Al2O3 were used as filter elements. During the operation of membrane elements, there is a drop in specific productivity associated with their contamination. Contamination of ultrafiltration membranes is considered as irreversible deposition of high-molecular substances, petroleum products and fats on the surface or in the pores of the membrane. However, with proper technical operation, it is possible to increase the service life of the membranes. The paper considers two strategies for maintenance of membrane elements based on their washing (regeneration) at certain intervals. The choice of the method and mode of regeneration of membrane elements is determined depending on the type of membrane material and on the specific operating conditions of their operation. For the regeneration of polymer tubular membranes due to their anisotropic design and the fragile connection between the active (fine-porous) and drainage (coarse-porous) layers, a chemical washing method using kerosene as a reagent is proposed. For ceramic membranes, due to the peculiarities of their production by sintering at high temperatures, two regeneration methods are possible: physical and chemical. The physical method consisted in using permeate backwash of membrane pores. Experiments have shown that it is most effective to regenerate membrane elements with a 30% drop in specific productivity by backwash, since it does not require the use of additional reagents and their subsequent disposal.

Membrane Fabrication for Carbon Dioxide Separation: A Critical Review

AbstractMembrane fabrication methods, mechanisms, and modification of membranes for CO2 separation are discussed. Various types of membrane materials with high CO2 separation performance are summarized. Rapid prototyping can achieve precise control of the thickness of membranes and freely design the spatial structure of membranes, which provides a new development direction for material application and process combination. Hence, a critical comparison of membrane fabrication using different methods can provide a comprehensive overview on the potential of the rapid prototyping technology in membrane fabrication. This is important to demonstrate the prospects of the membrane technology development for CO2 separation.

Simultaneous removal of dissolved sulphide and dissolved methane from anaerobic effluents with hollow fibre membrane contactors.

Dissolved gases in the effluent of anaerobic reactors, specifically dissolved methane (D-CH4) and sulphide (S2-), are a drawback for anaerobic-based sewage treatment plants (STPs). This article studied the simultaneous desorption/removal of both gases from anaerobic effluents with hollow fibre membrane contactors (HFMCs), evaluating two types of membrane materials (e.g. microporous and dense) at different operating conditions (atmospheric air as sweeping gas or vacuum, and different gas/liquid flows and vacuum pressures). The transfer of other gases, such as O2 and CO2, was studied as well. Desorption/removal efficiencies up to 99% for D-CH4 and 100% for S2- were obtained, with the higher efficiencies reported for the dense HFMC and with air as sweeping gas. It was found that the removal mechanism for S2- was oxidation with O2 from the air. In addition, the use of air as sweeping gas allowed the obtention of a nearly O2 saturated effluent, with more elevated dissolved oxygen concentrations in the microporous HFMC. Finally, it was found that the higher mass-transfer resistance in the dense membrane was compensated by a better performance in the liquid phase (lower mass-transfer resistance) in this unit, which allowed better D-CH4 desorption efficiencies.

Research and Design of Etching Line about Nuclear Track Membrane

Nuclear track membrane is a new type of membrane material with uniform pore size distribution. It can be used as a high-precision filtration membrane and there is a wide range of applications in sewage treatment, cell filtration, and biomedicine. The main production processes of nuclear track membrane include heavy ion irradiation and chemical etching, so there is a great significance about the research and design of etching lines. The main contents studied in this paper include the physical design principle of the etched line, the basic engineering structure, the basic control system architecture, and a complete HMI. The research plays an important role in the development and large-scale application of nuclear track membrane in this paper.

First-use hypersensitivity reactions during hemodialysis

Hypersensitivity reactions during hemodialysis result from the interaction between blood constituents and the hemodialysis membrane. Different types of membrane materials, including cellulose, substituted cellulose, or synthetic noncellulose, are used in dialyzers' manufacture which can affect the frequency and type of reaction seen. Two types of reactions, classified as Type A and Type B, have been described. Type A reaction is far less common but more severe than Type B. The following is a case of Type A reaction in a 63-year-old Caucasian male who had his first hemodialysis prescribed with a synthetic noncellulose membrane. His hemodialysis session was aborted and the reaction was successfully managed. Subsequent dialysis sessions were performed, uneventfully, with a substituted cellulose membrane. This case illustrates the importance of remaining vigilant and cognizant of the possibility of hypersensitivity reactions to hemodialysis membranes, as some of the reactions could be potentially life-threatening.

Cross-Linking With Diamine Monomers to Prepare Graphene Oxide Composite Membranes With Varying D-Spacing for Enhanced Desalination Properties.

As a new type of membrane material, graphene oxide (GO) can easily form sub-nanometer interlayer channels, which can effectively screen salt ions. The composite membrane and structure with a high water flux and good ion rejection rate were compared by the cross-linking of GO with three different diamine monomers: ethylenediamine (EDA), urea (UR), and p-phenylenediamine (PPD). X-ray photoelectron spectroscopy (XPS) results showed that unmodified GO mainly comprises π-π interactions and hydrogen bonds, but after crosslinking with diamine, both GO and mixed cellulose (MCE) membranes are chemically bonded to the diamine. The GO-UR/MCE membrane achieved a water flux similar to the original GO membrane, while the water flux of GO-PPD/MCE and GO-EDA/MCE dropped. X-ray diffraction results demonstrated that the covalent bond between GO and diamine can effectively inhibit the extension of d-spacing during the transition between dry and wet states. The separation performance of the GO-UR/MCE membrane was the best. GO-PPD/MCE had the largest contact angle and the worst hydrophilicity, but its water flux was still greater than GO-EDA/MCE. This result indicated that the introduction of different functional groups during the diamine monomer cross-linking of GO caused some changes in the performance structure of the membrane.

Next generation air conditioner for sustainable cooling solutions

Generally in summer, air conditioning systems are essential for improving the human comfort and productivity. The mechanical vapor compression system (VCS) is probably the most used system. However, the refrigerant used in VCS is harmful to the environment and the initial cost is high. So, the aim of this study is to introduce a sustainable, energy-efficient and climate-friendly air conditioning system in which there is no refrigerant. The proposed system is the integration of two modules i.e., Direct evaporative cooling (DEC) module and vacuum-assisted isothermal membrane-based air dehumidification (VIMAD) module, where the DEC module will cool and humidify the entering air stream and then this cool and humidified air will enter into the VIMAD module and the air will get dehumidified. Finally, the output will be cool and dehumidified air at the exit of the system. In this paper, the proposed system is explained. Moreover, the basic principle of the DEC, the background of DEC and the basic principle of the VIMAD system, background on the types of membrane materials that can be used in VIMAD are explained. Also, the effects of various parameters on the performance of the DEC and VIMAD are presented.

Membrane Flash Index: Powerful and Perspicuous Help for Efficient Separation System Design.

There are different factors and indices to characterize the performance of a pervaporation membrane, but none of them gives information about their capabilities in the area of liquid separation compared to the most convenient alternative, which is distillation. Membrane flash index (MFLI) can be considered the first and only one that shows if the membrane is more efficient or not than distillation and quantifies this feature too. Therefore, the MFLI helps select the best separation alternative in the case of process design. In this study, the evaluation and capabilities of membrane flash index are comprehensively investigated in the cases of six aqueous mixtures: methyl alcohol–water, ethyl alcohol–water, isobutyl alcohol–water, tetrahydrofuran–water, N-butyl alcohol–water, and isopropanol–water. It must be concluded that the separation capacity of organophilic type membranes is remarkably lower than hydrophilic membranes in all cases of separation. The study of the MFLI is extended with the consideration of other binary interaction parameters like separation factor, permeation flux, selectivity, and pervaporation separation index (PSI) in order to find a descriptive relationship between them. For the same membrane material type, descriptive function can be determined between feed concentration and MFLI and PSI and separation factor, which can be used to calculate each other’s value. On the basis of the indices and especially the MFLI, a significant help can be given to the process design engineer to select the right liquid separation alternative and, in the case of pervaporation, find the most appropriate membrane.

Modeling of a square-shape ZnO, ZnS and AlN membrane for mems capacitive pressure-sensor applications

In this paper, mathematical modeling and simulation of a MEMS-based clamped square-shape membrane for capacitive pressure sensors have been performed. Three types of membrane materials were investigated (i.e. Zinc Oxide (ZnO), Zinc Sulfide (ZnS) and Aluminum Nitride (AlN)). Various performance parameters such as capacitance changes, deflection, nonlinearity, the sensitivity of the membrane structure for different materials and film-thicknesses have been considered using the Finite Element Method (FEM) and analytically determined using the FORTRAN environment. The simulation model outperforms in terms of the effective capacitance value. The results show that the membrane deflection is linearly related to the applied pressure. The ZnS membrane provides a capacitance of 0.023 pico-Farad at 25 kPa with a 42.5% relative capacitance changes to reference capacitance. Additionally, the results show that for ZnO and AlN membranes the deflection with no thermal stress is higher than that with thermal stress. However, an opposite behavior for the ZnS membrane structure has been observed. The mechanical and capacitance sensitivities are affected by the membrane thickness as the capacitance changes are inversely proportional to the membrane thickness. Such results open possibilities to utilize various materials for pressure sensor applications by means of the capacitance-based detection technique.

Membrane distillation for industrial wastewater treatment: Studying the effects of membrane parameters on the wetting performance

Substantial amounts of trace hazardous elements have been detected in industrial wastewater (e.g fluoride > 900 mg/L). Feed water characteristics, operational parameters, and membrane properties are major factors affecting flux and rejection of the MD process. Membrane parameters such as membrane material type and pore size have been investigated. Fluoride ion rejection was selected to setup a methodology to remove trace elements from wastewater by adjusting the membrane parameters in DCMD. Study of the fouling thickness of the MD membrane using pH and feed water composition revealed that a PVDF membrane with a smooth surface holds a thicker fouling layer, which enhances fluoride rejection while reducing the permeate flux. On the other hand, PTFE and PP membranes showed higher mass transfer and higher wetting performance, respectively. Therefore,a PVDF membrane with low organic feed water at higher alkaline pH can be utilized to obtain high-quality permeate, while PTFE can provide the highest flux with acceptable permeate water quality. Therefore, this methodology can be applied toidentify the optimum membrane to fit the required permeate flux, rejection requirements,and operating pH to treat any kind of non-volatileinorganic pollutants from industrial wastewater.

UV mediated attachment of short Arginine-Tryptophan antimicrobial peptides on reverse osmosis membrane surfaces inhibit Pseudomonas aeruginosa biofilm

Biofouling of membranes is a persistent challenge in many water purification processes including desalination. A biofilm consists of communities of organisms adhering to surfaces, thus increasing the anti-bacterial activity of the surfaces might inhibit biofilm formation and reduce the biofouling problem. Antimicrobial peptides (AMPs) attached to various surfaces for prevention of biofilm can be widely applicable for water purification technology. However, the mechanism of action of tethered AMPs is still poorly understood. Here we show a facile method to covalently attach AMPs on RO membrane surfaces, achieved by incorporation of the photoreactive 3-(4-benzoylphenyl)alanine (Bpa) into the AMP sequence RWRWRWA-(Bpa), concentration of the peptide on the surface by filtration, and subsequent irradiation with UV light. Bacteria viability on modified surfaces decreased up to 55% and biofilm inhibition was observed using Pseudomonas aeruginosa. The modification increased the surface hydrophilicity, reducing the water contact angle from 70°±5 to 54°±7, and moderately altered the performance of the membrane: permeate flux was reduced by 16–37%, and NaCl rejection increased 6%. This efficient modification method for immobilizing AMPs onto surfaces is broadly applicable to many types of membrane materials and may facilitate investigations of the mode of action of surface-tethered AMPs.

Rejection of Commonly Used Electrolytes in Asymmetric Flow Field Flow Fractionation: Effects of Membrane Molecular Weight Cutoff Size, Fluid Dynamics, and Valence of Electrolytes.

Asymmetric flow field flow fractionation (AF4) is an efficient size-based separation technique for the characterization of submicron size particulates. In AF4, membranes having various molecular weight cutoff sizes are used as a barrier to retain particles while allowing the carrier fluid containing electrolytes to permeate. Here, we have hypothesized that electrolyte rejection by the barrier membrane leads to the accumulation of electrolytes in the channel during operation. Electrolyte accumulation can cause various adverse effects that can lead to membrane fouling. An instrument setup containing a conductivity detector was assembled, and the rejection of commonly used carrier electrolytes such as trisodium citrate, ethylenediaminetetraacetic acid, sodium chloride, and ammonium carbonate was evaluated by varying the concentration, cross-flow rate, focusing flow rate, membrane material type, and cutoff sizes. The results showed that electrolyte rejection increased with a decrease in the electrolyte concentration and the molecular weight cutoff size (pore size) or with an increase in the charge state of the anion in the carrier electrolytes. We proposed an electrostatic repulsion-based rejection mechanism and verified it with the measurement of the rejection rate while varying the electrolyte concentration in the running media.