Zeitschriftenartikel: „Gas Separation Techniques“

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Durand, J., und V. Rouessac. „CVD techniques for gas separation membranes synthesis - characterization - applications“. Le Journal de Physique IV 11, PR3 (August 2001): Pr3–1053—Pr3–1063. http://dx.doi.org/10.1051/jp4:20013132.

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Sattar, Muhammad Awais, Matheus Martinez Garcia, Robert Banasiak, Luis M. Portela und Laurent Babout. „Electrical Resistance Tomography for Control Applications: Quantitative Study of the Gas-Liquid Distribution inside A Cyclone“. Sensors 20, Nr. 21 (25.10.2020): 6069. http://dx.doi.org/10.3390/s20216069.

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Phase separation based centrifugal forces is effective, and thus widely explored by the process industry. In an inline swirl separator, a core of the light phase is formed in the center of the device and captured further downstream. Given the inlet conditions, this gas core created varies in shape and size. To predict the separation behavior and control the process in an optimal way, the gas core diameter should be measured with the minimum possible intrusiveness. Process tomography techniques such as electrical resistance tomography (ERT) allows us to measure the gas core diameter in a fast and non-intrusive way. Due to the soft-field nature and ill-posed problem in solving the inverse problem, especially in the area of low spatial resolution, the reconstructed images often overestimate the diameter of the object under consideration leading to unreliable measurements. To use ERT measurements as an input for the controller, the estimated diameters should be corrected based on secondary measurements, e.g., optical techniques such as high-speed cameras. In this context, image processing and image analysis techniques were adapted to compare the diameter calculated by an ERT system and a fast camera. In this paper, a correction method is introduced to correct the diameter obtained by ERT based on static measurements. The proposed method reduced the ERT error of dynamic measurements of the gas core size from over 300% to below 20%, making it a reliable sensing technique for controlled separation processes.

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Elhenawy, Salma, Majeda Khraisheh, Fares AlMomani und Mohamed Hassan. „Key Applications and Potential Limitations of Ionic Liquid Membranes in the Gas Separation Process of CO2, CH4, N2, H2 or Mixtures of These Gases from Various Gas Streams“. Molecules 25, Nr. 18 (18.09.2020): 4274. http://dx.doi.org/10.3390/molecules25184274.

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Heightened levels of carbon dioxide (CO2) and other greenhouse gases (GHGs) have prompted research into techniques for their capture and separation, including membrane separation, chemical looping, and cryogenic distillation. Ionic liquids, due to their negligible vapour pressure, thermal stability, and broad electrochemical stability have expanded their application in gas separations. This work provides an overview of the recent developments and applications of ionic liquid membranes (ILMs) for gas separation by focusing on the separation of carbon dioxide (CO2), methane (CH4), nitrogen (N2), hydrogen (H2), or mixtures of these gases from various gas streams. The three general types of ILMs, such as supported ionic liquid membranes (SILMs), ionic liquid polymeric membranes (ILPMs), and ionic liquid mixed-matrix membranes (ILMMMs) for the separation of various mixed gas systems, are discussed in detail. Furthermore, issues, challenges, computational studies and future perspectives for ILMs are also considered. The results of the analysis show that SILMs, ILPMs, and the ILMMs are very promising membranes that have great potential in gas separation processes. They offer a wide range of permeabilities and selectivities for CO2, CH4, N2, H2 or mixtures of these gases. In addition, a comparison was made based on the selectivity and permeability of SILMs, ILPMs, and ILMMMs for CO2/CH4 separation based on a Robeson’s upper bound curves.

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El-Naggar, Ashraf Yehia. „Thermal and Hydrothermal Treatment of Silica Gels as Solid Stationary Phases in Gas Chromatography“. Journal of Analytical Methods in Chemistry 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/931067.

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Silica gel was prepared and treated thermally and hydrothermally and was characterized as solid stationary phase in gas chromatography. The characteristics have been evaluated in terms of polarity, selectivity, and separation efficiencies. These parameters were used to assess the outer silica surface contributions and the degree of surface deactivation brought about by different treatment techniques. The parent silica elutes the paraffinic hydrocarbons with high efficiency of separation and elutes aromatic hydrocarbons with nearly good separation and has bad separation of alcohols. The calcined silica at 500°C and 1000°C has a pronounced effect on the separation of aromatic hydrocarbons compared with the parent silica and hydrothermal treatment of silica. With respect to alcohols separation, the obtained bad separations using treated and untreated silica reflect the little effect of the thermal and hydrothermal treatment on the silica surface deactivation.

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Shekhah, Osama, Valeriya Chernikova, Youssef Belmabkhout und Mohamed Eddaoudi. „Metal–Organic Framework Membranes: From Fabrication to Gas Separation“. Crystals 8, Nr. 11 (31.10.2018): 412. http://dx.doi.org/10.3390/cryst8110412.

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Gas membrane-based separation is considered one of the most effective technologies to address energy efficiency and large footprint challenges. Various classes of advanced materials, including polymers, zeolites, porous carbons, and metal–organic frameworks (MOFs) have been investigated as potential suitable candidates for gas membrane-based separations. MOFs possess a uniquely tunable nature in which the pore size and environment can be controlled by connecting metal ions (or metal ion clusters) with organic linkers of various functionalities. This unique characteristic makes them attractive for the fabrication of thin membranes, as both the diffusion and solubility components of permeability can be altered. Numerous studies have been published on the synthesis and applications of MOFs, as well as the fabrication of MOF-based thin films. However, few studies have addressed their gas separation properties for potential applications in membrane-based separation technologies. Here, we present a synopsis of the different types of MOF-based membranes that have been fabricated over the past decade. In this review, we start with a short introduction touching on the gas separation membrane technology. We also shed light on the various techniques developed for the fabrication of MOF as membranes, and the key challenges that still need to be tackled before MOF-based membranes can successfully be used in gas separation and implemented in an industrial setting.

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Sadiq, Muhammad Munir, Kiyonori Suzuki und Matthew R. Hill. „Towards energy efficient separations with metal organic frameworks“. Chemical Communications 54, Nr. 23 (2018): 2825–37. http://dx.doi.org/10.1039/c8cc00331a.

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The huge energy requirement for industrial separations of chemical mixtures has necessitated the need for the development of energy efficient and alternative separation techniques in order to mitigate the negative environmental impacts associated with greenhouse gas emissions from fossil fuel combustions for energy generation.

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Lungu, Mihai, Raluca Giugiulan, Antoanetta Lungu, Madalin Bunoiu und Adrian Neculae. „The Aharonov-Bohm Effect and Transport Properties in Graphene Nanostructures“. Annals of West University of Timisoara - Physics 57, Nr. 1 (01.12.2013): 86–95. http://dx.doi.org/10.1515/awutp-2015-0110.

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Abstract This paper investigates the possibility to improve the filtering process of flue gas by separation of suspended nanoparticle using dielectrophoresis. The study focuses on the particles having an average radius of about 50-150 nm, that cannot be filtrated by classical techniques but have a harmful effect for environment and human health. The size distribution nanoparticles collected from the flue gas filters of a hazardous waste incinerator plant were evaluated. Based on obtained experimental data and a proposed mathematical model, the concentration distribution of nanoparticle suspended in flue gas inside a microfluidic separation device was analyzed by numerical simulations, using the finite element method. The performances of the device were described in terms of three new specific quantities related to the separation process, namely Recovery, Purity and Separation Efficiency. The simulations could provide the optimal values of control parameters for separation process, and aim to be a useful tool in designing microfluidic devices for separating nanoparticle from combustion gases.

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Mohammad R. Gharibzahedi, Sayyed, und Javad Karimi-Sabet. „Gas Separation in Nanoporous Graphene from Molecular Dynamics Simulation“. Chemical Product and Process Modeling 11, Nr. 1 (01.03.2016): 29–33. http://dx.doi.org/10.1515/cppm-2015-0059.

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Abstract Membrane separation processes are energetically efficient compared to the other techniques such as cryogenic distillation and gas adsorption techniques. It is well known that a membrane's permeance is inversely proportional to its thickness. Regard to its single atom thickness and its mechanical strength, nanoporous graphene has been proposed as a very promising candidate for highly efficient gas separation applications. In this work, using classical molecular dynamics, we report the separation performance of such membrane in a molecular-sieving process as a function of pore size and chemical functionalization of pore rim. To investigate the membrane separation capability, we have calculated the permeance of each gas molecule of the considered binary mixtures through the membranes and therefore the separation selectivity. We investigated the separation performance of nanoporous graphene for CO2/N2, H2/CH4 and He/CH4 with 50:50 proportions of each component and the separation selectivity has been calculated. We also calculated the potential of the mean force to characterize the energy profile for gas transmission. The separation selectivity reduced by increasing the pore size. However, presence of chemical functionally pores in the membrane increased the separation selectivity. Furthermore, the gas permeance through nanoporous graphene membranes is related not only to transport rate to the graphene surface as well as kinetic diameters but also to molecular adsorbed layer which is formed on the surface. The flux of molecules through the nanopores is also dependent on pore chemistry which is considered as gas-pore interactions in the molecular simulations and can be a sizable factor in simulation in contrast to experimental observations. This study suggests that nanoporous graphene could represent a suitable membrane for gas separation.

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Gil-Ramírez, Alicia, und Irene Rodriguez-Meizoso. „Purification of Natural Products by Selective Precipitation Using Supercritical/Gas Antisolvent Techniques (SAS/GAS)“. Separation & Purification Reviews 50, Nr. 1 (21.05.2019): 32–52. http://dx.doi.org/10.1080/15422119.2019.1617737.

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Faghihian, H., und M. Pirouzi. „Nitrogen separation from natural gas by modified clinoptilolite“. Clay Minerals 44, Nr. 3 (September 2009): 289–92. http://dx.doi.org/10.1180/claymin.2009.044.3.289.

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AbstractSeparation of nitrogen, the major impurity of natural gas, is necessary for quality improvement of the gas. In this study, purified and some ion-exchanged forms of clinoptilolite were used to separate N2 from natural gas. Competitive adsorption of mixtures of N2, CH4 and C2H6 by Cu2+ (Cu-Cp)-, Zn2+ (Zn-Cp)-, Ni2+ (Ni-Cp)- and Mn2+ (Mn-Cp)-exchanged samples was studied at different pressures and ambient temperature. Among the cations studied, Cu2+ has the lowest selectivity towards N2. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, BET N2 adsorption and wet chemical analysis techniques.

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BROWN, IAN, MARK BOWDEN, TIM KEMMITT, JEREMY WU und JULES CARVALHO. „NANOSTRUCTURED ALUMINA CERAMIC MEMBRANES FOR GAS SEPARATION“. International Journal of Modern Physics B 23, Nr. 06n07 (20.03.2009): 1015–20. http://dx.doi.org/10.1142/s0217979209060397.

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Nanostructured alumina ceramic templates have been fabricated by anodizing annealed high-purity aluminium foil. Pore diameter, pore separation and thickness in these alumina ceramics can be controlled using a range of acid electrolytes and anodizing voltage profiles. Thermal development of the structure of these robust and optically clear templates have been compared using XRD, thermal analysis and 27 Al MAS NMR techniques, showing that species substituted in the alumina lattice from decomposition of the acid electrolyte play a major role in determining the chemical and physical stability of the ceramic template at elevated temperatures. Deposition of ultrathin palladium films on the surface of these alumina templates creates robust membranes that enable hydrogen separation from mixed gas streams at elevated temperatures. Gas permeability measurements through these membranes as a function of temperature have demonstrated their very high selectivity for hydrogen.

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Hitchings, A., T. O'Doherty und N. Syred. „Submicrometre particle separation via high-speed gas centrifuges“. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 211, Nr. 1 (01.02.1997): 17–29. http://dx.doi.org/10.1243/0954408971529511.

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The separation of submicrometre particulate matter from gases is a problem that has attracted much interest over the years. Filter systems require low face velocities and hence tend to be of large size, while also requiring sophisticated, bulky, regeneration systems. A high-speed centrifuge which can be linked with a turbocharger has been developed which can remove particulates well into the submicrometre range in diameter. The centrifuge operates at speeds of up to 60 000 r/min, with the assistance of both axial thrust air bearings and radial foil bearings. Experimental analysis of the centrifuge using particle sizing techniques etc. has shown the effectiveness of the system operating at a range of different flowrates. This has been done by comparing the relative effectiveness of the system for the different flowrates. The paper discusses the analysis of the separative efficiency (i.e. the ability to concentrate particles into a small proportion of the gas) of the present system and the predicted efficiencies of future systems.

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Sutrisna, Putu Doddy, Ronaldo Pangestu Hadi, Jonathan Siswanto und Giovanni J. Prabowo. „The CO2/CH4 Separation Potential of ZIF-8/Polysulfone Mixed Matrix Membranes at Elevated Particle Loading for Biogas Upgradation Process“. International Journal of Renewable Energy Development 10, Nr. 2 (30.11.2020): 213–19. http://dx.doi.org/10.14710/ijred.2021.33118.

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Biogas is a renewable energy that has been explored widely in Indonesia to substitute non-renewable energy. However, the presence of certain gas, such as carbon dioxide (CO2), can decrease the calorific value and generate greenhouse gas. Hence, the separation of CO2 from methane (CH4) occurs as a crucial step to improve the utilization of biogas. The separation of CH4/CO2 can be conducted using a polymeric membrane that needs no chemical, hence considered as an environmentally friendly technique. However, the utilization of polymeric membrane in gas separation processes is hampered by the trade-off between gas throughput and selectivity. To solve this problem, the incorporation of inorganic particles, such as Zeolitic Imidazolate Framework-8 (ZIF-8) particles, into the polymer matrix to improve the gas separation performance of the membrane has been conducted recently. In this research, ZIF-8 has been incorporated into Polysulfone matrix to form ZIF-8/Polysulfone-based membrane by simple blending and phase inversion techniques in flat sheet configuration. The pure gas permeation tests showed an increase in gas permeability (26 Barrer compared to 17 Barrer) after the inclusion of ZIF-8 particles with a slight decrease in CO2/CH4selectivity for particle loading more than 15wt. %. Therefore, the membrane with 15wt. % of particles showed the best performance in terms of gas selectivity. This result was due to the aggregation of ZIF-8 particles at particle loading higher than 15wt. %. Chemical analysis indicated an interaction between filler and polymer, and there were increases in the degree of crystallinity after the incorporation of ZIF-8.

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Yang, Liu, Molin Qin, Junchao Yang, Genwei Zhang und Jiana Wei. „Review on stationary phases and coating methods of MEMs gas chromatography columns“. Reviews in Analytical Chemistry 39, Nr. 1 (01.01.2020): 247–59. http://dx.doi.org/10.1515/revac-2020-0102.

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Abstract Gas chromatography (GC) is an important and widely used technique for separation and analysis in the field of analytical chemistry. Micro gas chromatography has been developed in response to the requirement for on-line analysis and on-site analysis. At the core of micro gas chromatography, microelectromechanical systems (MEMs) have the advantages of small size and low power consumption. This article introduces the stationary phases of micro columns in recent years, including polymer, carbon materials, silica, gold nanoparticles, inorganic adsorbents and ionic liquids. Preparation techniques ranging from classical coating to unusual sputtering of stationary phases are reviewed. The advantages and disadvantages of different preparation methods are analyzed. The paper introduces the separation characteristics and application progress of MEMs columns and discusses possible developments.

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Voegele-Kliewer, C. E., A. D. McMaster und G. W. Dirks. „A SEM/TEM examination of a ceramic membrane“. Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 682–83. http://dx.doi.org/10.1017/s0424820100144802.

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Materials other than polymers, e.g. ceramic silicates, are currently being investigated for gas separation processes. The permeation characteristics of one such material, Vycor (Corning Glass #1370), have been reported for the separation of hydrogen from hydrogen iodide. This paper will describe the electron microscopy techniques applied to reveal the porous microstructure of a Vycor membrane. The application of these techniques has led to an increased understanding in the relationship between the substructure and the gas transport properties of this material.

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DEMATTOS, I., M. DECASTRO und M. VALCARCEL. „Pervaporation: An integrated evaporation/gas-diffusion approach to analytical continuous separation techniques“. Talanta 42, Nr. 5 (Mai 1995): 755–63. http://dx.doi.org/10.1016/0039-9140(95)01491-s.

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Bisoi, Soumendu, Arun Kumar Mandal, Asheesh Singh und Susanta Banerjee. „Gas separation properties of Troeger’s base-bridged polyamides“. e-Polymers 17, Nr. 4 (27.06.2017): 283–93. http://dx.doi.org/10.1515/epoly-2016-0291.

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AbstractA series of new polyamides (PAs) has been prepared from a Troeger base-bridged diamine (TB), 2,8- diamino-4,10-dimethyl-6H,12H-5,11-methanodibenzo[1,5]-diazocine and different commercially available diacid monomers via the conventional polycondensation method. Dense membranes were prepared from the PAs by solution casting and solvent evaporation techniques. The synthesized PAs showed high glass transition temperature (283–290°C), 10% weight loss up to temperature 431°C in air, and tensile strength up to 91 MPa. The PA membranes showed higher permeability than some commercially used glassy polymers (PCO2 up to 109 and PO2 up to 21 Barrer) and permselectivity (PCO2/PCH4 up to 53.7 and PO2/PN2 up to 7.52) in comparison to many other PAs published in the literature.

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Lackner, G., F. J. S. Alhanati, S. A. Shirazi, D. R. Doty und Z. Schmidt. „Numerical Simulation of the Gas-Liquid Flow in a Rotary Gas Separator“. Journal of Energy Resources Technology 120, Nr. 1 (01.03.1998): 41–48. http://dx.doi.org/10.1115/1.2795008.

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The presence of free gas at the pump intake adversely affects the performance of an electrical submersible pump (ESP) system, often resulting in low efficiency and causing operational problems. One method of reducing the amount of free gas that the pump has to process is to install a rotary gas separator. The gas-liquid flow associated with the down hole installation of a rotary separator has been investigated to address its overall phase segregation performance. A mathematical model was developed to investigate factors contributing to gas-liquid separation and to determine the efficiency of the separator. The drift-flux approach was used to formulate this complex two-phase flow problem. The turbulent diffusivity was modeled by a two-layer mixing-length model and the relative velocity between phases was formulated based on published correlations for flows with similar characteristics. The well-known numerical procedure of Patankar-Spalding for single-phase flow computations was extended to this two-phase flow situation. Special discretization techniques were developed to obtain consistent results. Special under relaxation procedures were also developed to keep the gas void fraction in the interval [0, 1]. Predicted mixture velocity vectors and gas void fraction distribution for the two-phase flow inside the centrifuge are presented. The model’s predictions are compared to data gathered on a field scale experimental facility to support its invaluable capabilities as a design tool for ESP installations.

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Xu, Peng Xia, und Yan Feng Geng. „Wet Gas Flow Metering Based on Differential Pressure and BSS Techniques“. Advanced Materials Research 383-390 (November 2011): 4922–27. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.4922.

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Wet gas flow is a typical two-phase flow with low liquid fractions. As differential pressure signal contains rich information of flow parameters in two-phase flow metering, a new method is proposed for wet gas flow metering based on differential pressure (DP) and blind source separation (BSS) techniques. DP signals are from a couple of slotted orifices and the BSS method is based on time-frequency analysis. A good relationship between the liquid flow rate and the characteristic quantity of the separated signal is established, and a differential pressure correlation for slotted orifice is applied to calculate the gas flow rate. The calculation results are good with 90% relative errors less than ±10%. The results also show that BSS is an effective method to extract liquid flow rate from DP signals of wet gas flow, and to analysis different interactions among the total DP readings.

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Cerdà, Víctor, Jessica Avivar und Amalia Cerdà. „Laboratory automation based on flow techniques“. Pure and Applied Chemistry 84, Nr. 10 (27.06.2012): 1983–98. http://dx.doi.org/10.1351/pac-con-11-11-14.

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Flow techniques have undoubtedly aroused special interest in relation to many other automatic methodologies of analysis. Ever since segmented flow analysis (SFA) was developed by Skeggs in 1957, flow techniques have been in continuous evolution toward new develop-ments. There is no solid argument in favor of using any particular flow technique separately; rather, substantial advantages can be derived from their combination. Since flow-based methods are nonseparative tools, the advantages of combining flow techniques with separation techniques are noteworthy. High selectivity can be achieved by coupling them with liquid chromatography (LC), gas chromatography (GC), solid-phase extraction (SPE), or capillary electrophoresis (CE). Thus, a detailed description of flow techniques, their evolution, their hyphenation advantages, and a critical comparison between current developed methods exploiting flow techniques aimed at solving present analytical needs are reviewed in this article.

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Ahmad, Fatin Nurwahdah, Norazlianie Sazali und Mohd Hafiz Dzafran Othman. „A Mini Review on Carbon Molecular Sieve Membrane for Oxygen Separation“. Journal of Modern Manufacturing Systems and Technology 4, Nr. 1 (27.03.2020): 23–35. http://dx.doi.org/10.15282/jmmst.v4i1.3800.

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Membrane-based technology has proved its practicality in gas separation through its performance. Various type of membranes has been explored, showing that each type of them have their own advantages and disadvantages. Polymeric membranes have been widely used to separate O2/N2, however, its drawbacks lead to the development of carbon molecular sieve membrane. Carbon molecular sieve membranes have demonstrated excellent separation performance for almost similar kinetic diameter molecules such as O2/N2. Many polymer precursors can be used to produce carbon molecular sieve membrane through carbonization process or also known as heat treatment. This paper discusses the variety of precursors and carbonization parameters to produce high quality and performance of carbon molecular sieve membranes. This paper covers the evaluation in advancement and status of high-performance carbon membrane implemented for separating gas, comprising the variety of precursor materials and the fabrication process that involve many different parameters, also analysis of carbon membranes properties in separating various type of gas having high demand in the industries. The issues regarding the current challenges in developing carbon membrane and approaches with the purpose of solving and improving the performance and applications of carbon membrane are included in this paper. Also, the advantages of the carbon membrane compared to other types of membranes are highlighted. Observation and understanding the variables affecting the quality of membrane encourage the optimization of conditions and techniques in producing high-performance membrane.

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Tiuca, Ioana, Katalin Nagy und Radu Oprean. „Recent developments in fatty acids profile determination in biological samples - a review“. Revista Romana de Medicina de Laborator 23, Nr. 4 (01.12.2015): 371–84. http://dx.doi.org/10.1515/rrlm-2015-0035.

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Abstract The present paper is a literature review of the recent years dealing with the most important separation techniques of fatty acids in biological samples. Our aim was to make a synthesis of the analytical methods used, to note the most used ones, but also to mention other methods that are less utilized, which can have important advantages (such as less time consuming, greener reagents, etc.). Gas-chromatographic separation methods were described and compared to liquid chromatographic separations of fatty acids in different types of biological samples. In the same time, the importance of determining fatty acids profiles in biological samples was revealed, pointing out the possible implications in diagnostics of different types of disorders or remarking different profiles compared to healthy states.

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Shimekit, Biruh, Azmi Mohd Shariff, Hilmi Mukhtar, Mohamad Azmi Bustam, Ali E. I. Elkhalifah, Sami Ullah und Nadia Riaz. „Interfacial Defects on Mixed Matrix Membranes and Mitigation Techniques for Gas Separation: A Review“. Applied Mechanics and Materials 625 (September 2014): 653–56. http://dx.doi.org/10.4028/www.scientific.net/amm.625.653.

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Development of novel mixed matrix membranes (MMMs) has become frontier candidates for improving the upper bound trade-off curve between permeability and selectivity of gases for industrial polymeric membranes. However, fabrication of ideal MMMs is practically challenging as the dispersion of inorganic phase into the polymer may produce polymeric-inorganic interfacial defects at the vicinity of the polymer matrix. For instance, the inorganic phase may cause interfacial void, polymer chain rigidification or partial pore blockage on the overall MMMs. Since there are only few studies that specifically focus on the issues of the interfacial morphology of MMMs, therefore, the present study provides brief description of the aforementioned interfacial (non-ideal) defects of MMMs and summarizes the techniques used to repair the interfacial defects for enhanced gas separation in MMMs.

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Zimmerman, Catherine M., Anshu Singh und William J. Koros. „Diffusion in gas separation membrane materials: A comparison and analysis of experimental characterization techniques“. Journal of Polymer Science Part B: Polymer Physics 36, Nr. 10 (30.07.1998): 1747–55. http://dx.doi.org/10.1002/(sici)1099-0488(19980730)36:10<1747::aid-polb16>3.0.co;2-9.

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Yuenyao, Chalad, Thawat Chittrakarn, Yutthana Tirawanichakul und Suksawat Sirijarukul. „Surface Modification of Asymmetric Polysulfone/Polyethylene Glycol Membranes by DC Ar-Glow Discharge Plasma“. International Journal of Polymer Science 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/4759150.

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Polysulfone/polyethylene glycol (PSF/PEG) membranes were prepared by dry/wet phase inversion method. Effects of direct current glow discharge plasma using argon as working gas on morphological structures and gas separation properties of membranes were studied. Alteration of membrane characteristics were analyzed by various techniques like contact angle, scanning electron microscope, Fourier transform infrared spectroscopy, and dynamic mechanical thermal analysis. Gas separation properties were measured in terms of permeation and ideal O2/N2 selectivity. Results showed that hydrophilic and gas separation properties of PSF/PEG membranes increased by plasma surface modification. It was also shown that the dosage of PEG and plasma treatment affected the morphological structures and mechanical and gas separation properties. The macro voids and transmembrane structure disappeared with a little amount of PEG dosage. Pore size and mechanical strength tend to decrease with increasing PEG dosage up to 10 wt%. Glass transition temperature (Tg) receded from 201.8 to 143.7°C for pure PSF and PSF/PEG with PEG dosage of 10 wt%. O2 and N2 gases permeation through the 10-minute plasma treated membranes tend to increase. However, the permeation strongly dispersed when treatment time was more extended.

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Dang, Huynh N. P., und Joselito P. Quirino. „Analytical Separation of Carcinogenic and Genotoxic Alkenylbenzenes in Foods and Related Products (2010–2020)“. Toxins 13, Nr. 6 (28.05.2021): 387. http://dx.doi.org/10.3390/toxins13060387.

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Alkenylbenzenes are potentially toxic (genotoxic and carcinogenic) compounds present in plants such as basil, tarragon, anise star and lemongrass. These plants are found in various edible consumer products, e.g., popularly used to flavour food. Thus, there are concerns about the possible health consequences upon increased exposure to alkenylbenzenes especially due to food intake. It is therefore important to constantly monitor the amounts of alkenylbenzenes in our food chain. A major challenge in the determination of alkenylbenzenes in foods is the complexity of the sample matrices and the typically low amounts of alkenylbenzenes present. This review will therefore discuss the background and importance of analytical separation methods from papers reported from 2010 to 2020 for the determination of alkenylbenzenes in foods and related products. The separation techniques commonly used were gas and liquid chromatography (LC). The sample preparation techniques used in conjunction with the separation techniques were various variants of extraction (solvent extraction, liquid-liquid extraction, liquid-phase microextraction, solid phase extraction) and distillation (steam and hydro-). Detection was by flame ionisation and mass spectrometry (MS) in gas chromatography (GC) while in liquid chromatography was mainly by spectrophotometry.

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Salleh, W. N. W., Norazlianie Sazali, H. Hasbullah, Norhaniza Yusof, Juhana Jaafar und Ahmad Fauzi Ismail. „Gas Permeation Study of Carbon Tubular Membrane by Manipulating Carbonization Temperature Profile“. Advanced Materials Research 1112 (Juli 2015): 145–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1112.145.

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Membrane-based separation technology has been widely applied for large-scale industrial CO2 capture due to its lower energy consumption and low pollutant production compared with other conventional techniques. The desirable properties in high performance gas separation membranes involve steps that must carefully be designed and controlled. This study investigates the role of carbonization temperature in the fabrication and performance analysis of carbon membranes prepared from polyimide. A commercial polyimide, Matrimid® 5218, was coated on the surface of ceramic tube to produce supported polymer membrane. The prepared polymer membrane was then carbonized under nitrogen atmosphere to produce supported carbon membrane for CO2/CH4 separation. The resulting carbon tubular membrane separation performance was evaluated using pure gas permeation test. Results showed that the suitable carbonization temperature for Matrimid-based carbon tubular membrane was at 850 °C. The highest selectivity for CO2/CH4 of 82.47 was obtained from carbon tubular membrane prepared at 850 °C.

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Lipinski, Gregor, und Markus Richter. „Raman Sensor for the Determination of Gas Solubility“. Physchem 1, Nr. 2 (04.08.2021): 176–88. http://dx.doi.org/10.3390/physchem1020012.

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Efficient and environmentally responsible use of resources requires the development and optimization of gas separation processes. A promising approach is the use of liquids that are designed for specific tasks, e.g., the capture of carbon dioxide or other greenhouse gases. This requires an accurate determination of gas solubilities for a broad range of temperatures and pressures. However, state of the art measurement techniques are often very time consuming or exhibit other pitfalls that prevent their use as efficient screening tools. Here, we show that the application of Raman spectroscopy through a compact measuring system can simplify data acquisition for the determination of gas solubilities in liquids. To demonstrate that this approach is expedient, we determined gas solubilities of carbon dioxide in water for three isotherms T = (288.15, 293.15, 298.15) K over a pressure range from p = (0.5–5) MPa and in three imidazolium-based ionic liquids for one isotherm T = 298.15 K at pressures from p = (0.1–5) MPa. When compared to data in the literature, all results are within the reported uncertainties of the measurement techniques involved. The developed analysis method eliminates the need for a lengthy volume or mass calibration of the sample prior to the measurements and, therefore, allows for fast screening of samples, which can help to advance gas separation processes in scientific and industrial applications.

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Suliman, F. „Off-line optimization of the separation of 2,4-dinitrophenylhydrazones by gas chromatography using chemometric techniques“. Talanta 56, Nr. 1 (04.01.2002): 175–83. http://dx.doi.org/10.1016/s0039-9140(01)00554-9.

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Gauglitz, Günter, Benedikt Wimmer, Tanja Melzer und Carolin Huhn. „Glyphosate analysis using sensors and electromigration separation techniques as alternatives to gas or liquid chromatography“. Analytical and Bioanalytical Chemistry 410, Nr. 3 (02.11.2017): 725–46. http://dx.doi.org/10.1007/s00216-017-0679-x.

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Chung Chong, Kok, Yin Yin Chan, Woei Jye Lau, Soon Onn Lai, Ahmad Fauzi Ismail und Hui Shan Thiam. „Preparation and characterization of polysulfone membrane coated with poly(ether block amid) for oxygen enrichment process“. Malaysian Journal of Fundamental and Applied Sciences 15, Nr. 1 (04.02.2019): 50–53. http://dx.doi.org/10.11113/mjfas.v15n2019.1226.

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Oxygen enriched air (OEA) is widely applied in various areas such as chemical and medical applications. Currently, cryogenic distillation and pressure swing adsorption are the two common technologies that being commercially used for i the production of OEA. However, these two techniques are not economically favorable due to required intensive energy and large built-up area. With the advancement of membrane technology in separation process, it garners the interest from both industrial and academic to explore the feasibility of membrane in gas separation. In this study, polysulfone (PSF) hollow fiber membranes with poly(ether block amide) (PEBAX) coating were used for the separation of O2/N2 gas. The hollow fiber membranes used in this work were fabricated by phase inversion spinning process using PSF pellet, along with N,N-dimetyhlacetamide (DMAc) and ethanol (EtOH) as solvent and co-solvent, whereas tetrahydrofuran (THF) as additive. The fabricated membrane exhibited dense structure in the inner layer whereas finger like layer at the outer surface. The formation of this structure was attributed by rapid phase inversion of the solution arose from strong solvent used. The EDX surface mapping analysis confirmed the formation of PEBAX coating on the membrane surface. Gas permeation study in this work illustrated that the pristine PSF membrane exhibited better gas separation performance relative to the PEBAX coated membrane with 20% higher in terms of permeance. The results obtained from this work suggested that the PEBAX coating enhanced the membrane surface but not certain to improve the gas separation performance. Further study on the PEBAX materials for the membrane coating is essential to polish its potential in gas separation.

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Shirvani, Hemmat, Saeid Maghami, Ali Pournaghshband Isfahani und Morteza Sadeghi. „Influence of Blend Composition and Silica Nanoparticles on the Morphology and Gas Separation Performance of PU/PVA Blend Membranes“. Membranes 9, Nr. 7 (05.07.2019): 82. http://dx.doi.org/10.3390/membranes9070082.

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Polymer blending and mixed-matrix membranes are well-known modification techniques for tuning the gas separation properties of polymer membranes. Here, we studied the gas separation performance of mixed-matrix membranes (MMMs) based on the polyurethane/poly(vinyl alcohol) (PU/PVA) blend containing silica nanoparticles. Pure (CO2, CH4, N2, O2) and mixed-gas (CO2/N2 and CO2/CH4) permeability experiments were carried out at 10 bar and 35 °C. Poly(vinyl alcohol) (PVA) with a molecular weight of 200 kDa (PVA200) was blended with polyurethane (PU) to increase the CO2 solubility, while the addition of silica particles to the PU/PVA blend membranes augmented the CO2 separation performance. The SEM images of the membranes showed that the miscibility of the blend improved by increasing the PVA contents. The membrane containing 10 wt % of PVA200 (PU/PVA200–10) exhibited the highest CO2/N2~32.6 and CO2/CH4~9.5 selectivities among other blend compositions, which increased to 45.1 and 15.2 by incorporating 20 wt % nano-silica particles.

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Lee, Hing-Biu. „Review of Analytical Methods for the Determination of Nonylphenol and Related Compounds in Environmental Samples“. Water Quality Research Journal 34, Nr. 1 (01.02.1999): 3–36. http://dx.doi.org/10.2166/wqrj.1999.002.

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Abstract Analytical methods published in the last 20 years for the extraction, chromato-graphic separation, and quantification of alkylphenol ethoxylates (APEO) and related compounds in environmental samples are reviewed. Examples of various isolation and preconcentration techniques for water, effluent, sediment and sludge are presented. This includes procedures from the classical liquid-liquid and Soxhlet extraction to the up-to-date solid phase and supercritical fluid extraction. Chromatographic separation of APEO by normal and reversed phase liquid chromatography (LC) and capillary column gas chromatography (GC) is compared. A variety of quantification methods involving the common LC and GC detectors as well as various mass spectrometric techniques are also discussed.

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Parys, Wioletta, Małgorzata Dołowy und Alina Pyka-Pająk. „Current Strategies for Studying the Natural and Synthetic Bioactive Compounds in Food by Chromatographic Separation Techniques“. Processes 9, Nr. 7 (24.06.2021): 1100. http://dx.doi.org/10.3390/pr9071100.

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The present study summarizes the new strategies including advanced equipment and validation parameters of liquid and gas chromatography methods i.e., thin-layer chromatography (TLC), column liquid chromatography (CLC), and gas chromatography (GC) suitable for the identification and quantitative determination of different natural and synthetic bioactive compounds present in food and food products, which play an important role in human health, within the period of 2019–2021 (January). Full characteristic of some of these procedures with their validation parameters is discussed in this work. The present review confirms the vital role of HPLC methodology in combination with different detection modes i.e., HPLC-UV, HPLC-DAD, HPLC-MS, and HPLC-MS/MS for the determination of natural and synthetic bioactive molecules for different purposes i.e., to characterize the chemical composition of food as well as in the multi-residue analysis of pesticides, NSAIDs, antibiotics, steroids, and others in food and food products.

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Latif, Ahmad Abdul, Jimoh K. Adewole, Suzylawati Binti Ismail, Leo Choe Peng und Abdullah S. Sultan. „Membrane Separation of CO₂from Natural Gas: A State-of-the-Art Review on Material Development“. Defect and Diffusion Forum 333 (Januar 2013): 135–47. http://dx.doi.org/10.4028/www.scientific.net/ddf.333.135.

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Natural gas (NG) processing and membrane technology are two very important fields that are of great significance due to increasing demand for energy as well as separation of gas mixtures. While NG is projected to be the number one primary source of energy by 2050, membrane separation is a commercially successful competitor to other separation techniques for energy efficient gas separation processes [1]. Most of the NG produced in the world is coproduced with acid gases such as CO2which need to be removed to increase the caloric value of NG. A comprehensive review of research efforts in CO2separation from natural gas is required to capture details of the current scientific and technological progresses on the development of new membrane materials with better separation performance, and the improvement of properties of the existing ones. This paper presents the progress that has been achieved in eliminating the limitations that dominate the large scale application of membrane materials at the present time. Various polymers that have been developed to resist plasticization and the method employed to fabricate these polymers are highlighted. Also the range of plasticization pressures (together with corresponding selectivities and permeabilities at these pressures) that have so far been achieved by these fabrication methods is presented. It is believed that this review will serve as a good reference source especially for research in design and development of membrane materials with better resistance to CO2-induced plasticization.

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Konegger, Thomas, Herwig Peterlik und Rajendra K. Bordia. „Micro-/Mesoporous Polymer-Derived Ceramic Structures Using Molecular Porogens“. Key Engineering Materials 742 (Juli 2017): 310–16. http://dx.doi.org/10.4028/www.scientific.net/kem.742.310.

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Micro-and mesoporous ceramics demonstrate promising properties for applications in energy-and environment-related fields. Due to their high thermal and chemical stability, they are particularly suited for separation in harsh thermal or chemical environments, e.g. as membrane materials for the separation of gas mixtures. In this work, we present the use of a preceramic poly(vinyl)silazane in combination with organic molecular porogens for the generation of micro-/mesoporous non-oxide ceramic structures. Microporosity is generated during the pyrolytic conversion process, while the addition of molecular porogens, to be removed during the heat-treatment, enables further control of the micro-/mesopore structure. A systematic investigation of various porogens showed the suitability of polystyrene for this purpose. Based on these findings, the pore structure and pore connectivity of polysilazane/polystyrene-derived structures were evaluated using gas physisorption and small angle X-ray scattering techniques. This material was further investigated by preparing asymmetric membranes consisting of micro-/mesoporous polysilazane/polystyrene-derived layers on porous ZrO2/TiO2 supports. The potential for gas separation applications was then demonstrated by single-gas permance evaluation of the generated structures at temperatures up to 300 °C.

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Goh, Pei Sean, Kar Chun Wong, Lukka Thuyavan Yogarathinam, Ahmad Fauzi Ismail, Mohd Sohaimi Abdullah und Be Cheer Ng. „Surface Modifications of Nanofillers for Carbon Dioxide Separation Nanocomposite Membrane“. Symmetry 12, Nr. 7 (02.07.2020): 1102. http://dx.doi.org/10.3390/sym12071102.

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CO2 separation is an important process for a wide spectrum of industries including petrochemical, refinery and coal-fired power plant industries. The membrane-based process is a promising operation for CO2 separation owing to its fundamental engineering and economic benefits over the conventionally used separation processes. Asymmetric polymer–inorganic nanocomposite membranes are endowed with interesting properties for gas separation processes. The presence of nanosized inorganic nanofiller has offered unprecedented opportunities to address the issues of conventionally used polymeric membranes. Surface modification of nanofillers has become an important strategy to address the shortcomings of nanocomposite membranes in terms of nanofiller agglomeration and poor dispersion and polymer–nanofiller incompatibility. In the context of CO2 gas separation, surface modification of nanofiller is also accomplished to render additional CO2 sorption capacity and facilitated transport properties. This article focuses on the current strategies employed for the surface modification of nanofillers used in the development of CO2 separation nanocomposite membranes. A review based on the recent progresses made in physical and chemical modifications of nanofiller using various techniques and modifying agents is presented. The effectiveness of each strategy and the correlation between the surface modified nanofiller and the CO2 separation performance of the resultant nanocomposite membranes are thoroughly discussed.

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Guo, Fei, Bingzhang Li, Rui Ding, Dongsheng Li, Xiaobin Jiang, Gaohong He und Wu Xiao. „A Novel Composite Material UiO-66@HNT/Pebax Mixed Matrix Membranes for Enhanced CO2/N2 Separation“. Membranes 11, Nr. 9 (07.09.2021): 693. http://dx.doi.org/10.3390/membranes11090693.

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Mixing a polymer matrix and nanofiller to prepare a mixed matrix membrane (MMM) is an effective method for enhancing gas separation performance. In this work, a unique UiO-66-decorated halloysite nanotubes composite material (UiO-66@HNT) was successfully synthesized via a solvothermal method and dispersed into the Pebax-1657 matrix to prepare MMMs for CO2/N2 separation. A remarkable characteristic of this MMM was that the HNT lumen provided the highway for CO2 diffusion due to the unique affinity of UiO-66 for CO2. Simultaneously, the close connection of the UiO-66 layer on the external surface of HNTs created relatively continuous pathways for gas permeation. A suite of microscopy, diffraction, and thermal techniques was used to characterize the morphology and structure of UiO-66@HNT and the membranes. As expected, the embedding UiO-66@HNT composite materials significantly improved the separation performances of the membranes. Impressively, the as-obtained membrane acquired a high CO2 permeability of 119.08 Barrer and CO2/N2 selectivity of 76.26. Additionally, the presence of UiO-66@HNT conferred good long-term stability and excellent interfacial compatibility on the MMMs. The results demonstrated that the composite filler with fast transport pathways designed in this study was an effective strategy to enhance gas separation performance of MMMs, verifying its application potential in the gas purification industry.

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Held, C. B., und D. K. Robbins. „Investigation of Liquid and Gas Chromatography Techniques for Separation of Diastereomers of -( -Methylbenzyl) Amino Isobutyric Acid“. Journal of Chromatographic Science 41, Nr. 8 (01.09.2003): 422–27. http://dx.doi.org/10.1093/chromsci/41.8.422.

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D’Orazio, Giovanni, Chiara Fanali, Chiara Dal Bosco, Alessandra Gentili und Salvatore Fanali. „Chiral separation and analysis of antifungal drugs by chromatographic and electromigration techniques: Results achieved in 2010–2020“. Reviews in Analytical Chemistry 40, Nr. 1 (01.01.2021): 220–52. http://dx.doi.org/10.1515/revac-2021-0136.

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Abstract The determination and separation of enantiomers is an interesting and important topic of research in various fields, e.g., biochemistry, food science, pharmaceutical industry, environment, etc. Although these compounds possess identical physicochemical properties, a pair of enantiomers often has different pharmacological, toxicological, and metabolic activities. For this reason, chiral discrimination by using chromatographic and electromigration techniques has become an urgent need in the pharmaceutical field. This review intends to offer the “state of the art” about the separation of chiral antifungal drugs and several related precursors by both liquid and gas chromatography, as well as electromigration methods. This overview is organized into two sections. The first one describes general considerations on chiral antifungal drugs. The second part deals with the main analytical methods for the enantiomeric discrimination of these drugs, including a brief description of chiral selectors and stationary phases. Moreover, many recent applications attesting the great interest of analytical chemists in the field of enantiomeric separation are presented.

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Ameen, Ayesha, und Shahid Raza. „Metaproteomics approaches and techniques: A review“. International Journal of Advances in Scientific Research 3, Nr. 5 (05.06.2017): 49. http://dx.doi.org/10.7439/ijasr.v3i5.4167.

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Extensive studies have been done on metagenomics for various microbial communities. The advancements in metagenomics level led to the need of metaproteomics approaches. Metaproteomics involve the identification, function and expression of various proteins present in microbial community, it also involves the identification and expression analysis of stress related proteins. The concepts of metaproteomics come with advancement in proteomics techniques which includes 2D gel electrophoresis for the identification of proteins and peptides in a particular microbial community. Mass spectrometry which is used to separate the proteins by desorption and ionization using a gas on a liquid medium. MALDI use for protein identification and separation, connected with TOF to give better results. The metaproteomics approaches become more advanced when HPLC and LC were used for peptides and protein with computational tools to sequence the peptide and protein. It is concluded that there is a requirement of research in metaproteomics. Many scientists have done research on these approaches but there is lack of better quality and desirable results.

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Mahenthiran, Ashvin Viknesh, und Zeinab Abbas Jawad. „A Prospective Concept on the Fabrication of Blend PES/PEG/DMF/NMP Mixed Matrix Membranes with Functionalised Carbon Nanotubes for CO2/N2 Separation“. Membranes 11, Nr. 7 (10.07.2021): 519. http://dx.doi.org/10.3390/membranes11070519.

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With an ever-increasing global population, the combustion of fossil fuels has risen immensely to meet the demand for electricity, resulting in significant increase in carbon dioxide (CO2) emissions. In recent years, CO2 separation technology, such as membrane technology, has become highly desirable. Fabricated mixed matrix membranes (MMMs) have the most desirable gas separation performances, as these membranes have the ability to overcome the trade-off limitations. In this paper, blended MMMs are reviewed along with two polymers, namely polyether sulfone (PES) and polyethylene glycol (PEG). Both polymers can efficiently separate CO2 because of their chemical properties. In addition, blended N-methyl-2-pyrrolidone (NMP) and dimethylformamide (DMF) solvents were also reviewed to understand the impact of blended MMMs’ morphology on separation of CO2. However, the fabricated MMMs had challenges, such as filler agglomeration and void formation. To combat this, functionalised multi-walled carbon nanotube (MWCNTs-F) fillers were utilised to aid gas separation performance and polymer compatibility issues. Additionally, a summary of the different fabrication techniques was identified to further optimise the fabrication methodology. Thus, a blended MMM fabricated using PES, PEG, NMP, DMF and MWCNTs-F is believed to improve CO2/nitrogen separation.

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Jamil, Asif, Momina Zulfiqar, Usama Arshad, Subhan Mahmood, Tanveer Iqbal, Sikander Rafiq und Muhammad Z. Iqbal. „Development and Performance Evaluation of Cellulose Acetate-Bentonite Mixed Matrix Membranes for CO2 Separation“. Advances in Polymer Technology 2020 (13.12.2020): 1–12. http://dx.doi.org/10.1155/2020/8855577.

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Membrane science is a state-of-the-art environmentally green technology that ascertains superior advantages over traditional counterparts for CO2 capture and separation. In this research, mixed matrix membranes (MMMs) comprising cellulose acetate (CA) with various loadings of bentonite (Bt) clay were fabricated by adopting the phase-inversion technique for CO2/CH4 and CO2/N2 separation. The developed pristine and MMMs were characterized for morphological, thermal, structural, and mechanical analyses. Several techniques such as scanning electron microscopy, thermogravimetric analysis, Fourier transformed infrared spectroscopy, and nano-indentation investigations revealed the promising effect of Bt clay in MMMs as compared to pristine CA membrane. Nano-indentation test identified that elastic modulus and hardness of the MMM with 1 wt. loading was increased by 64% and 200%, respectively, compared to the pristine membrane. The permeability decreased with the incorporation of Bt clay due to uniform dispersion of filler attributed to enhanced tortuosity for the gas molecules. Nevertheless, an increase in gas separation performance was observed with Bt addition up to 1 wt. loading. The opposite trend prevailed with increasing Bt concentration on the separation performance owing to filler agglomeration and voids creation. The maximum value of ideal selectivity (CO2/CH4) was achieved at 2 bar pressure with 1 wt. % Bt loading, which is 79% higher than the pristine CA membrane. For CO2/N2, the ideal selectivity was 123% higher compared to the pristine membrane with 1 wt. % Bt loading at 4 bar pressure.

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Asif, Khadija, Serene Sow Mun Lock, Syed Ali Ammar Taqvi, Norwahyu Jusoh, Chung Loong Yiin, Bridgid Lai Fui Chin und Adrian Chun Minh Loy. „A Molecular Simulation Study of Silica/Polysulfone Mixed Matrix Membrane for Mixed Gas Separation“. Polymers 13, Nr. 13 (01.07.2021): 2199. http://dx.doi.org/10.3390/polym13132199.

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Polysulfone-based mixed matrix membranes (MMMs) incorporated with silica nanoparticles are a new generation material under ongoing research and development for gas separation. However, the attributes of a better-performing MMM cannot be precisely studied under experimental conditions. Thus, it requires an atomistic scale study to elucidate the separation performance of silica/polysulfone MMMs. As most of the research work and empirical models for gas transport properties have been limited to pure gas, a computational framework for molecular simulation is required to study the mixed gas transport properties in silica/polysulfone MMMs to reflect real membrane separation. In this work, Monte Carlo (MC) and molecular dynamics (MD) simulations were employed to study the solubility and diffusivity of CO2/CH4 with varying gas concentrations (i.e., 30% CO2/CH4, 50% CO2/CH4, and 70% CO2/CH4) and silica content (i.e., 15–30 wt.%). The accuracy of the simulated structures was validated with published literature, followed by the study of the gas transport properties at 308.15 K and 1 atm. Simulation results concluded an increase in the free volume with an increasing weight percentage of silica. It was also found that pure gas consistently exhibited higher gas transport properties when compared to mixed gas conditions. The results also showed a competitive gas transport performance for mixed gases, which is more apparent when CO2 increases. In this context, an increment in the permeation was observed for mixed gas with increasing gas concentrations (i.e., 70% CO2/CH4 > 50% CO2/CH4 > 30% CO2/CH4). The diffusivity, solubility, and permeability of the mixed gases were consistently increasing until 25 wt.%, followed by a decrease for 30 wt.% of silica. An empirical model based on a parallel resistance approach was developed by incorporating mathematical formulations for solubility and permeability. The model results were compared with simulation results to quantify the effect of mixed gas transport, which showed an 18% and 15% percentage error for the permeability and solubility, respectively, in comparison to the simulation data. This study provides a basis for future understanding of MMMs using molecular simulations and modeling techniques for mixed gas conditions that demonstrate real membrane separation.

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Raikar, Prachi, und Gurupadayya Bannimath. „Recent Trends in Chiral Separation-A Collective Paradigm of Selected Chiral Impurities“. Current Pharmaceutical Analysis 16, Nr. 5 (15.06.2020): 456–73. http://dx.doi.org/10.2174/1573412915666181219144507.

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Chiral separation plays a very important role in the modern pharmaceutical analysis and will continue in upcoming years. Separation and identification of chiral impurities are indispensable. According to ICH guidelines, only the active enantiomer of the drug has to be marketed, so there is a focus on separation of the inactive enantiomer which acts as a chiral impurity. The impurities present in the enantiomers also pose various toxic adverse effects on bioavailability and efficacy, hence the need to separate these impurities will forever be trending. This review primarily focuses on the separation techniques like Capillary Electrophoresis (CE), High-Performance Liquid Chromatography (HPLC), Gas Chromatography (GC), and Supercritical Fluid Chromatography (SFC) followed by the year-wise trend in the separation of selected chiral impurities. In the coming years, researchers should work on using ultra-fast, selective, and sensitive methods for the effective separation of chiral impurities.

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Zellweger, C., C. Hüglin, J. Klausen, M. Steinbacher, M. K. Vollmer und B. Buchmann. „Inter-comparison of four different carbon monoxide measurements techniques and evaluation of the long-term carbon monoxide time series of Jungfraujoch“. Atmospheric Chemistry and Physics Discussions 9, Nr. 1 (26.01.2009): 2381–415. http://dx.doi.org/10.5194/acpd-9-2381-2009.

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Abstract. The 12-year record (1996–2007) of continuous carbon monoxide (CO) measurements of the high-alpine site Jungfraujoch (JFJ), Switzerland, was investigated with a focus on trend analysis. To date this is one of the longest time series of continuous CO measurements in the free troposphere over Central Europe. A significant negative trend was observed at JFJ with a decrease of 21.4±0.3% in the investigated period, or an average annual decrease of 2.65±0.04 ppb/yr (1.78%/yr). These results were compared with emission inventory data reported to the Long-range Transboundary Air Pollution (LRTAP) Convention. It could be shown that long range transport significantly influences the CO levels observed at JFJ, with air masses of non-European origin contributing to at least a third to observed mixing ratios. Such trend analysis and inter-comparison with emission inventories are only possible with data of known quality. To this end, the Non-dispersive Infrared Absorption (NDIR) technique used for CO measurements at JFJ was inter-compared over two months using three additional analytical techniques, namely Vacuum UV Resonance Fluorescence (VURF), gas chromatographic separation with a mercuric oxide reduction detector (GC/HgO), and gas chromatographic separation followed by reduction on a nickel catalyst and analysis by a flame ionization detector (GC/FID). The agreement among all techniques was better than 2% for one-hourly averages which confirmed the suitability of the NDIR method for CO measurements even at remote sites.

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Selahle, Shirley Kholofelo, Anele Mpupa und Philiswa Nosizo Nomngongo. „A review of extraction, analytical, and advanced methods for the determination of neonicotinoid insecticides in environmental water matrices“. Reviews in Analytical Chemistry 40, Nr. 1 (01.01.2021): 187–203. http://dx.doi.org/10.1515/revac-2021-0134.

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Abstract Neonicotinoid insecticides are widely used to kill and prevent unwanted insects from attacking growing crops. Extensive use of insecticides in various compartments of the environment has led to adverse effect on the health of living organisms. Several analytical methodologies have been reported for extraction and quantification of neonicotinoid insecticides in various matrices. The analytical detection techniques range from traditional to modern or state of the art quantification methods. The traditional analytical techniques include gas chromatography and high-performance liquid chromatography. These methods require extensive sample pretreatment before identification, separation, and quantification of target analytes. Advanced detection techniques refer to the sensor technologies based on optical, biorecognition, molecular imprinted polymers chemical, and piezoelectric. In this review, a summary and explanation of the various traditional analytical and advanced methodologies for extraction, separation, detection, and quantification of neonicotinoid insecticides residue in water samples have been discussed.

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Garcia, Xavier, Maria Sabaté, Jorge Aubets, Josep Jansat und Sonia Sentellas. „Ion Mobility–Mass Spectrometry for Bioanalysis“. Separations 8, Nr. 3 (16.03.2021): 33. http://dx.doi.org/10.3390/separations8030033.

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This paper aims to cover the main strategies based on ion mobility spectrometry (IMS) for the analysis of biological samples. The determination of endogenous and exogenous compounds in such samples is important for the understanding of the health status of individuals. For this reason, the development of new approaches that can be complementary to the ones already established (mainly based on liquid chromatography coupled to mass spectrometry) is welcomed. In this regard, ion mobility spectrometry has appeared in the analytical scenario as a powerful technique for the separation and characterization of compounds based on their mobility. IMS has been used in several areas taking advantage of its orthogonality with other analytical separation techniques, such as liquid chromatography, gas chromatography, capillary electrophoresis, or supercritical fluid chromatography. Bioanalysis is not one of the areas where IMS has been more extensively applied. However, over the last years, the interest in using this approach for the analysis of biological samples has clearly increased. This paper introduces the reader to the principles controlling the separation in IMS and reviews recent applications using this technique in the field of bioanalysis.

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Kobayashi, Yasunori, Seiichi Takami, Momoji Kubo und Akira Miyamoto. „Non-equilibrium molecular simulation studies on gas separation by microporous membranes using dual ensemble molecular simulation techniques“. Fluid Phase Equilibria 194-197 (März 2002): 319–26. http://dx.doi.org/10.1016/s0378-3812(01)00690-2.

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Alqaheem, Yousef, und Abdulaziz A. Alomair. „Microscopy and Spectroscopy Techniques for Characterization of Polymeric Membranes“. Membranes 10, Nr. 2 (24.02.2020): 33. http://dx.doi.org/10.3390/membranes10020033.

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Polymeric membrane is a proven technology for water purification and wastewater treatment. The membrane is also commercialized for gas separation, mainly for carbon dioxide removal and hydrogen recovery. Characterization techniques are excellent tools for exploring the membrane structure and the chemical properties. This information can be then optimized to improve the membrane for better performance. In this paper, characterization techniques for studying the physical structure such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) are discussed. Techniques for investigating the crystal structure such as X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) are also considered. Other tools for determining the functional groups such Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance (NMR) are reviewed. Methods for determining the elemental composition such as energy-dispersion X-ray spectroscopy (EDS), X-ray fluorescent (XRF), and X-ray photoelectron spectroscopy (XPS) are explored. The paper also gives general guidelines for sample preparation and data interpretation for each characterization technique.

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