Littérature scientifique sur le sujet « Organic charge separators »
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Articles de revues sur le sujet "Organic charge separators"
1
Francisco, Mark, Cheng-Tang Pan, Bo-Hao Liao, Mao-Sung Wu, Ru-Yuan Yang, Jay Chu, Zhi-Hong Wen, Chien-Feng Liao et Yow-Ling Shiue. « Fabrication and Analysis of Near-Field Electrospun PVDF Fibers with Sol-Gel Coating for Lithium-Ion Battery Separator ». Membranes 11, no 3 (9 mars 2021) : 186. http://dx.doi.org/10.3390/membranes11030186.
Texte intégralRésumé :
Environmental and economic concerns are driving the demand for electric vehicles. However, their development for mass transportation hinges largely on improvements in the separators in lithium-ion batteries (LIBs), the preferred energy source. In this study, innovative separators for LIBs were fabricated by near-field electrospinning (NFES) and the sol-gel method. Using NFES, poly (vinylidene fluoride) (PVDF) fibers were fabricated. Then, PVDF membranes with pores of 220 nm and 450 nm were sandwiched between a monolayer and bilayer of the electrospun fibers. Nanoceramic material with organic resin, formed by the sol-gel method, was coated onto A4 paper, rice paper, nonwoven fabric, and carbon synthetic fabric. Properties of these separators were compared with those of a commercial polypropylene (PP) separator using a scanning electron microscope (SEM), microtensile testing, differential scanning calorimetry (DSC), ion-conductivity measurement, cyclic voltammetry (CV), and charge-discharge cycling. The results indicate that the 220 nm PVDF membrane sandwiched between a bilayer of electrospun fibers had excellent ionic conductivity (~0.57 mS/cm), a porosity of ~70%, an endothermic peak of ~175 °C, better specific capacitance (~356 mAh/g), a higher melting temperature (~160 °C), and a stable cycle performance. The sol-gel coated nonwoven fabric had ionic conductivity, porosity, and specific capacitance of ~0.96 mS/cm., ~64%, and ~220 mAh/g, respectively, and excellent thermal stability despite having a lower specific capacitance (65% of PP separator) and no peak below 270 °C. The present study provides a significant step toward the innovation of materials and processes for fabricating LIB separators.
2
Ahmed, Faheem, Shalendra Kumar, Nagih Mohammed Shaalan, Osama Saber, Sarish Rehman, Abdullah Aljaafari, Hatem Abuhimd et Mohammad Alshahrani. « Synergistic Effect of Hexagonal Boron Nitride-Coated Separators and Multi-Walled Carbon Nanotube Anodes for Thermally Stable Lithium-Ion Batteries ». Crystals 12, no 2 (18 janvier 2022) : 125. http://dx.doi.org/10.3390/cryst12020125.
Texte intégralRésumé :
In this work, we report the development of separators coated with hexagonal boron nitride (hBN) to improve the thermal stability of Li-ion batteries (LIBs). Aiming to achieve a synergistic effect of separators and anodes on thermal stability and electrochemical performance, multiwalled carbon nanotubes (MWCNTs) were prepared via plasma-enhanced chemical vapor deposition (PECVD) method and used as potential anode materials for LIBs. The grown MWCNTs were well characterized by using various techniques which confirmed the formation of MWCNTs. The prepared MWCNTs showed a crystalline structure and smooth surface with a diameter of ~9–12 nm and a length of ~10 μm, respectively. Raman spectra showed the characteristic peaks of MWCNTs and BN, and the sharpness of the peaks showed the highly crystalline nature of the grown MWCNTs. The electrochemical studies were performed on the fabricated coin cell with a MWCNT anode using a pristine and BN-coated separators. The results show that the cell with the BN-coated separator in a conventional organic carbonate-based electrolyte and MWCNTs as the anode resulted in a discharge capacity (at 65 °C) of ~567 mAhg−1 at a current density of 100 mAg−1 for the first cycle, and delivered a capacity of ~471 mAhg−1 for 200 cycles. The columbic efficiency was found to be higher (~84%), which showed excellent reversible charge–discharge behavior as compared with the pristine separator (69%) after 200 cycles. The improved thermal performance of the LIBs with the BN-coated separator and MWCNT anode might be due to the greater homogeneous thermal distribution resulting from the BN coating, and the additional electron pathway provided by the MWCNTs. Thus, the fabricated cell showed promising results in achieving the stable operation of the LIBs even at higher temperatures, which will open a pathway to solve the practical concerns over the use of LIBs at higher temperatures without compromising the performance.
3
Huang, Yi-Chen, Yin-Ju Yen, Yu-Hsun Tseng et Sheng-Heng Chung. « Module-Designed Carbon-Coated Separators for High-Loading, High-Sulfur-Utilization Cathodes in Lithium–Sulfur Batteries ». Molecules 27, no 1 (30 décembre 2021) : 228. http://dx.doi.org/10.3390/molecules27010228.
Texte intégralRésumé :
Lithium–sulfur batteries have great potential as next-generation energy-storage devices because of their high theoretical charge-storage capacity and the low cost of the sulfur cathode. To accelerate the development of lithium–sulfur technology, it is necessary to address the intrinsic material and extrinsic technological challenges brought about by the insulating active solid-state materials and the soluble active liquid-state materials. Herein, we report a systematic investigation of module-designed carbon-coated separators, where the carbon coating layer on the polypropylene membrane decreases the irreversible loss of dissolved polysulfides and increases the reaction kinetics of the high-loading sulfur cathode. Eight different conductive carbon coatings were considered to investigate how the materials’ characteristics contribute to the lithium–sulfur cell’s cathode performance. The cell with a nonporous-carbon-coated separator delivered an optimized peak capacity of 1112 mA∙h g−1 at a cycling rate of C/10 and retained a high reversible capacity of 710 mA∙h g−1 after 200 cycles under lean-electrolyte conditions. Moreover, we demonstrate the practical high specific capacity of the cathode and its commercial potential, achieving high sulfur loading and content of 4.0 mg cm−2 and 70 wt%, respectively, and attaining high areal and gravimetric capacities of 4.45 mA∙h cm−2 and 778 mA∙h g−1, respectively.
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Maraschky, Adam M., Melissa L. Meyerson, Stephen J. Percival, Martha M. Gross, Amanda S. Peretti, Erik D. Spoerke et Leo J. Small. « Optimizing the Current Collector for Sodium Iodide-Metal Halide Catholytes in Low-Temperature Molten Sodium Batteries ». ECS Meeting Abstracts MA2022-02, no 55 (9 octobre 2022) : 2135. http://dx.doi.org/10.1149/ma2022-02552135mtgabs.
Texte intégralRésumé :
Low-cost, long-duration energy storage is critically needed for a robust electric grid powered by renewable sources. In the pursuit of meeting this need, low-temperature (<130 °C) molten sodium batteries (MNaBs) with NaI-metal halide molten salt catholytes have been developed. This battery design circumvents many of the safety concerns caused by metal dendrites and flammable organic solvents found in Li-metal or Li-ion batteries. It also drastically reduces the high-temperature material requirements and operating costs compared to traditional MNaBs, such as ZEBRA, which operate near 300 °C. The presented battery operates at 110 °C—just above the melting point of Na (98 °C). It features a molten Na anode, a NaSICON ceramic separator, and a NaI/AlCl3 catholyte. Among the key challenges to widespread utilization of these emerging MNaBs is reducing the overpotential on the cathode while operating at practical current densities over numerous cycles. To improve the performance of the cathode, we examined the electrochemical behavior of a variety of disk electrode materials, including W, Mo, Ta, and glassy carbon (GC) in a 3-electrode configuration. A custom cell was designed to mimic a full battery with separators for both the reference and counter electrodes. Excess molten salt was used to keep bulk concentrations practically constant over the course of the experiments. This enabled experiments that isolated the working electrode from other battery elements, such as a changing catholyte or the NaSICON interfaces. Voltammetry, electrochemical impedance spectroscopy, chronopotentiometry, and chronoamperometry were used to evaluate each material’s charge/discharge kinetics and stability. Instability on charging is hypothesized to be due to iodine (I2) adsorption on rapid iodide (I-) oxidation. Discharge, on the other hand, is limited by the transport of triiodide (I3 -), which depends on the battery’s state of charge. Insights from these studies serve as the foundation for the rational design of high-surface area electrodes for iodide-based molten salt catholytes. After initial testing in the 3-electrode cell, the performance of several high surface area current collectors was evaluated in rate tests and continuous cycling of lab-scale battery cells. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
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Dalwadi, Shrey, Arnav Goel, Constantine Kapetanakis, David Salas-de la Cruz et Xiao Hu. « The Integration of Biopolymer-Based Materials for Energy Storage Applications : A Review ». International Journal of Molecular Sciences 24, no 4 (16 février 2023) : 3975. http://dx.doi.org/10.3390/ijms24043975.
Texte intégralRésumé :
Biopolymers are an emerging class of novel materials with diverse applications and properties such as superior sustainability and tunability. Here, applications of biopolymers are described in the context of energy storage devices, namely lithium-based batteries, zinc-based batteries, and capacitors. Current demand for energy storage technologies calls for improved energy density, preserved performance overtime, and more sustainable end-of-life behavior. Lithium-based and zinc-based batteries often face anode corrosion from processes such as dendrite formation. Capacitors typically struggle with achieving functional energy density caused by an inability to efficiently charge and discharge. Both classes of energy storage need to be packaged with sustainable materials due to their potential leakages of toxic metals. In this review paper, recent progress in energy applications is described for biocompatible polymers such as silk, keratin, collagen, chitosan, cellulose, and agarose. Fabrication techniques are described for various components of the battery/capacitors including the electrode, electrolyte, and separators with biopolymers. Of these methods, incorporating the porosity found within various biopolymers is commonly used to maximize ion transport in the electrolyte and prevent dendrite formations in lithium-based, zinc-based batteries, and capacitors. Overall, integrating biopolymers in energy storage solutions poses a promising alternative that can theoretically match traditional energy sources while eliminating harmful consequences to the environment.
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Wisinska, Natalia H., Magdalena Skunik-Nuckowska, Sławomir Dyjak, Wladyslaw Wieczorek et Pawel J. Kulesza. « Poly(norepinephrine) As a Functional Additive for Hybrid Cellulose/Agarose-Based Hydrogel Membranes : Application to Supercapacitors ». ECS Meeting Abstracts MA2022-02, no 54 (9 octobre 2022) : 2051. http://dx.doi.org/10.1149/ma2022-02542051mtgabs.
Texte intégralRésumé :
A rapidly growing interest in renewable energy sources requires not only developing efficient energy storage systems but also incorporating a greater number of eco-friendly components. Electrochemical double-layer capacitors (EDLCs) are a class of energy storage devices capable to store the electrical charge due to the separation of oppositely charged ions in the electrical field which results in the formation of an electrical double layer (EDL) at the electrode/electrolyte interface. EDLCs consist in general of two porous carbon-based electrodes pre-soaked with electrolyte and separated with a membrane (separator). The simple electrostatic mechanism of energy storage, coupled with a lack of chemical changes and faradaic transitions during operation, results in high electrical capacitance compared to classical capacitors, significantly higher power density in contrast to batteries, and practically unlimited life span. Currently, commercial EDLCs typically rely on organic solvents, such as acetonitrile or propylene carbonate, with the addition of ionically-conductive salts. However, there are several drawbacks when it comes to practical applications involving particular low conductivity, toxicity, flammability and high cost. This resulted in an increased interest in aqueous electrolytes such as KOH, H2SO4 or simple inorganic salts, which although they have a limited potential window, exhibit many positive features including higher ionic conductivity, lower viscosity, increased safety, lower cost and ease of assembly under ambient atmosphere. Modern and technologically advanced charge storage devices often require high safety flexible and deformable devices for specific applications. However, at the current state-of-the-art, the EDLCs suffer from two prominent limitations (i) the possibility of electrolyte leakage and (ii) high standards of technology to safely encapsulate electrolytes in the device. Therefore, a lot of research is held to develop alternatives for currently used liquid (aqueous and organic) electrolytes. One of the solutions to overcome these limitations are solid-state EDLCs. Those systems use an ionically-conductive polymer or hydrogel membrane, which serves as both the separator and the electrolyte. Cellulose, built of β-(1→4)-linked D-glucose units, is one of the most prevalent and easily degradable biopolymers. Albeit, its wide availability, biodegradability and low cost, the usage of cellulose is limited due to insolubility in most common solvents. The recent alternative, to toxic and flammable organic compounds, such as N, N- dimethylformamide/N2O4, N-methylmorpholine oxide (NMMO), are ionic liquids (ILs), that have been gaining lately a lot of attention in energy storage systems. Various ILs based on imidazolium, pyridinium and ammonium cation paired with strongly basic anion (e.g., OAc-, HCOO-) were also recently used to dissolve cellulose. However, the requirements of high-purity syntheses and the cost of some of the cations/anions may affect a large scale application. Therefore, our research refers to an alternative route of chemical regeneration of microcrystalline cellulose, i.e. its dissolution using an aqueous mixture of NaOH/urea, and further processing into a hydrogel membrane in the presence of cross-linking agent epichlorohydrin. To improve the mechanical strength and electrolyte uptake, in-situ polymerized norepinephrine and agarose were subsequently incorporated obtaining an interpenetrating polymer network (IPN). The structure and morphology of the membranes were characterized with SEM/EDX, CP/MAS 13C-NMR, AT-FTIR, TGA, contact angle, and elementary analysis. The ionic conductivity was determined using impedance spectroscopy over a wide range of temperatures (5-60°C). The relation between stress and strain in the materials was also determined to diagnose the mechanical properties. The cellulose-based hydrogel membranes were further used as a support for various aqueous electrolytes, including H2SO4, Na2SO4, i.e. most commonly used for aqueous EDLCs. Also, the alternative electrolyte was used, i.e. silicotungstic acid, H4SiW12O40 which according to our recent results seems to be a promising candidate to replace conventional acidic electrolytes [1]. The designed systems were compared, in terms of energy, power and cycleability, with their analogues using conventional polypropylene separators and a liquid electrolyte. [1] N.H. Wisinska, M. Skunik-Nuckowska, S. Dyjak, P.J. Kulesza, Factors affecting the performance of electrochemical capacitors operating in Keggin-type silicotungstic acid electrolyte, Appl. Surf. Sci. 530 (2020) 147273, https://doi.org/10.1016/j.apsusc.2020.147273 Acknowledgement Financial support was provided by the National Science Center under Preludium 19 grant no. 2020/37//N/ST4/01679. This work was implemented as a part of Operational Project Knowledge Education Development 2014–2020 co-financed by the European Social Fund, Project No POWR.03.02.00-00-I007/16-00 (POWER 2014-2020)
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Su, Tzu-Chi, et Han-Yi Chen. « Suppression of Dendrite Formation with Porous and Conductive Carbon on Anode for Aqueous Zinc-Ion Hybrid Capacitors ». ECS Meeting Abstracts MA2022-01, no 3 (7 juillet 2022) : 489. http://dx.doi.org/10.1149/ma2022-013489mtgabs.
Texte intégralRésumé :
Electrochemical energy storage systems with high power and energy density have been drawing attention with the increasing demand for electric vehicles and portable electronics. However, rechargeable nonaqueous lithium-based energy storage system, which is the most widely-used type, is still limited with unsafety, resulting from its toxic organic electrolyte and flammability. Hence, zinc has been considered a strong candidate in rechargeable aqueous energy storage systems. With high theoretical capacity (823 mAh g−1) and low operating potential (−0.76 V vs. standard hydrogen electrode), Zinc-ion batteries show the highest energy density among all aqueous batteries at low cost. Moreover, to improve the low power density and short cycle life for batteries, Zinc-ion hybrid capacitors (ZICs) are introduced by combining the characterizations of both battery and supercapacitor. Despite the advantages of ZICs mentioned above, the instability during the charging and discharging process are unneglectable. Formation of dendrites due to uneven zinc electrostripping and electroplating process on zinc metal anode can cause internal short-circuit after they penetrate the separators of the batteries. Hydrogen generation also results in low Columbic efficiency. To enhance electrochemically stability for zinc metal anode, a zinc anode modification with porous reduced graphene oxide (rGO) is reported. Electrostatic Spray Deposition (ESD) is a technique through which liquid droplets of a precursor solution are accelerated by a high DC voltage to form aerosol and deposit on the heated substrate. By coating rGO with ESD on zinc anode, the study of how the morphology of coating affects the electrostripping and electroplating process can be discussed in detail. The modified materials were examined by scanning electron microscopy and electrochemical active surface area. The porous rGO coated zinc anode shows small voltage polarization and long cycle life. With porous rGO coated zinc anode, the charge distribution on the electrode can be optimized, and the porous structure can guide pathways for zinc ions. Furthermore, the zinc deposition is much uniform than bare zinc during cycling, which can be observed in several operando techniques, including transmission X-ray microscopy and optical microscopy.
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Meng, Jiang-Ping, Yun Gong, Qiang Lin, Miao-Miao Zhang, Pan Zhang, Hui-Fang Shi et Jian-Hua Lin. « Metal–organic frameworks based on rigid ligands as separator membranes in supercapacitor ». Dalton Transactions 44, no 12 (2015) : 5407–16. http://dx.doi.org/10.1039/c4dt03702b.
Texte intégral
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Choi, Hyoungwoo, et Byoung-Sun Lee. « Pilot Scale Hybrid Organic/Inorganic Coatings on a Polyolefin Separator to Enhance Dimensional Stability for Thermally Stable Long-Life Rechargeable Batteries ». Polymers 14, no 21 (22 octobre 2022) : 4474. http://dx.doi.org/10.3390/polym14214474.
Texte intégralRésumé :
The electric vehicle and energy storage markets have grown rapidly in recent years. Thermal runaway caused by malfunctioning Li-ion batteries is an urgent issue with many causes (e.g., mechanical, electrical, and thermal abuse). The most common cause of thermal runaway is the formation of an internal short circuit because of damage to the separator. There has been significant effort to improve the design of separators, but to our knowledge, only inorganic nanoparticle coatings are used in commercial Li-ion batteries. Here, hybrid organic/inorganic coating layers are synthesized in a pilot-scale process that was developed from a crosslinkable polyamide-imide synthesis technique. The fabrication process is optimized to achieve reproducible hybrid organic/inorganic coating layers that are thin (≤4 μm), permeable (≤250 s/100 cc), and thermally stable beyond 150 °C. The hybrid coating layer is applied to mini-18650 Li-ion cells to show that the discharge capacity did not change at low discharge rates, and the retention capacity after 500 cycles was better than that of the reference cells used for comparison. This work demonstrates that a novel hybrid coating layer has the potential to improve the stability of commercial Li-ion batteries.
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Lin, Yupo J. « (Invited) Applications of Novel Electrochemical Technologies for Sustainable Fuel/Chemical Production and Resources Recovery ». ECS Meeting Abstracts MA2022-02, no 27 (9 octobre 2022) : 1043. http://dx.doi.org/10.1149/ma2022-02271043mtgabs.
Texte intégralRésumé :
Electrochemical processes offer R&D opportunities toward decarbonization and resource recovery for circular economics. Innovate material produced by advancing manufacture techniques further widens its applications. In this presentation, we will discuss electrochemical process designs and material innovation to address technical and economic challenges of separations in biochemical/ biofuel production, resources recovery, CO2 utilization and impaired water treatment. In separations, the electrically driven force enabling selective capture of charged species and/or in-situ aqueous pH manipulation provides high energy efficiency, low capital footprint and cost for industrial applications compared to other separation technologies, e.g., separations by pressure-driven, thermally driven and biological-related. The common practices known are electrodialysis (ED), electrodeionization (EDI), capacitive deionization (CDI), cation intercalation desalination (CID), and ion concentration polarization (ICP). In these techniques, concentrated ions are separated from the liquid energy use is correlated with the quantity of ions removed. Therefore, the selective target capture provides “fit-for-purpose” separations. Pressure-driven processes cannot tune salinity for fit-for-purpose quality desalination but are effective at organic and biological species removal that electrochemical processes are not able to do. Thermal-driven processes cannot tune salinity for fit-for-purpose quality but are effective at organic and biological species removal. Biological-related processes typically apply bioelectrochemical reactions via microbes and bacteria to drive the removal of ions from the solution. In biological processes, ions are removed from the water solution. The ability to produce fit-for-purpose water has not been explored with biological processes, but they can treat targeted organics and biologicals. Compared to the pressure-driven membrane separation technologies used most in industrial separations, applications of selective separations have increased in recent years and becomes important to address the challenges of technology adaptation to climate change. For examples, the production of biofuel and bio-products to reduce green-house gas emission from fossil fuel and the non-conventional water supply for water-energy nexus have required high energy efficient and cost effective separation technologies. Innovative electrochemical separations can provide transformational impacts in advancing selective separations for highly energy efficient, small capital footprints and low processing cost. It, thus, enables the paradigm-shift of using alternative fuels and water supplies for industrial applications. We will discuss the key process performance metrics, energy consumption and processing rate, of various electrochemical technologies applied in biorefinery, waste to energy and water energy nexus to separate charges species from “dilute” aqueous phase. The ions separation performance demonstrated from various aqueous streams include 1) Inorganic and organic salts removal/capture in lignin valorization. and from bioprocessing streams in biofuel production; 2) volatile fatty acid removal/capture as well as biogas purification from solid waste anaerobic digester for waste to energy; 3) selective desalination of hardness, alkalinity, silica, and ammonia from impaired water for cooling water supply; 4)Capture and delivery for CO2 utilization. Critical issues in process design and material property to achieve electrochemical separation rate and energy efficiency for economic viability will be discussed.
Thèses sur le sujet "Organic charge separators"
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KARAMSHUK, SVITLANA. « Organic sensitizers for application in photonic and photovoltaic devices ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/76622.
Texte intégralRésumé :
With the increasing demand for reliable and efficient devices with minimal environmental impact, novel organic materials gain extreme interest in the research community and industry. In this work we present synthetic strategies towards new organic compounds as promising materials for dye sensitized solar cells (DSCs) and low-cost integrated optics along with the investigation of these materials in devices.
Despite the recent hype in the research community around DSCs, increasing efficiency of DSCs is still a challenge. In principle, one promising way to obtain DSCs with significantly enhanced efficiency lies in connecting an n-type photoelectrode (i.e. n-Dye/TiO2) with a p-type one (i.e. p-Dye/NiO) leading to a tandem cell composed by two serially connected photoactive electrodes, each contributing with its own photovoltage to the total photovoltage delivered by the cell. Applying such concept could theoretically lead to organic photovoltaic devices with up to 40% overall conversion yield. One of the main limitations in p-type systems, commonly based on NiO, arises from fast charge recombination between the photoinjected hole in NiO, and the reduced dye. Therefore it is crucially important to develop p-type chromophores which could produce a long-lived charge separated state and minimize back recombination.
We were thus triggered to explore new organic structures for potentially efficient chromophores for p-type devices, by considering that the intramolecular charge transfer, at the basis of efficient charge separation in donor-acceptor dyes, is strongly dependent on the electron-withdrawing ability of the acceptor. Herein we present charge separators based on organic push-pull systems of tryphenylamine donors and branched electron acceptors (SK2-3-4) based either on Dalton (SK2) or benzothidaziole acceptor groups (SK3-4) which were synthesized and characterized by steady state spectroscopic, electrochemical and computational means. All the dyes exhibit strong charge transfer bands in the visible regions with ground and excited state energetics which are favourable to the sensitization of NiO electrodes. The computational investigation revealed a clear directionality of the lowest excited state exhibiting a marked charge transfer character, shifting the electron density to the acceptor branches, an electronic situation which is favourable to the hole injection in p-type semiconductors. When tested in p-type DSCs the SK series was found capable to sensitize NiO electrodes. The charge recombination kinetics, probed by considering the charge transfer resistance at the NiO/electrolyte interface at a comparable chemical capacitance, showed that the dyes behaved similarly and that the higher Voc observed with the SK4 dye is ostensibly due to a positive shift of the valence band edge, consistent with the shift in the anodic current threshold observed in dark conditions.
The second part of this work is dedicated to synthesis and characterisation of metallo-organic materials for optoelectronic devices. Optical amplification plays crucial role in the transmission and manipulation of optical signals in modern telecomunications. Nowadays amplifiers, which rely on erbium ions in a glass matrix, suffer from difficulties in fabrication and the need of high pump power densities to produce gain. Here we show a newly synthesised series of organic fully halogenated optical amplifier materials.
We will compare the ability of materials with different halogen atoms in complexes with transition metals to provide population of triplets which together with the lack of CH or OH oscillators in the molecule, can be potentially used as an efficient chromophore to sensitise the erbium ions in a long-lifetime erbium complex. Finally by doping Er(FTPIP)3 with newly designed Zn and Co complexes, we aim to find differences in the lifetime emission from erbium at the important telecommunication wavelength of 1.5 μm.
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Maldonado, Omar. « Synthesis of charged cyclodextrin highly soluble in organic solvents for enantiomer separations in capillary electrophoresis ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/4211.
Texte intégralRésumé :
Synthesis of charged cyclodextrin highly soluble in organic solvents was
made by exchanging the inorganic counter ion (Na+) of heptakis (2,3-di-Omethyl-
6-O-sulfo)-ò-CD (Na7HDMS) with tetrabutylammonium (TBA+), to
produce TBA7HDMS. The same ion exchange was used to synthesize the TBA
salts of the analogous CDs TBA6HxDMS and TBA8ODMS. Indirect-UV
detection capillary electrophoresis (CE) and 1H NMR were used as the
characterization methods.
Separations of thirteen pharmaceuticals were made using TBA7HDMS as
the chiral resolving agent in aqueous CE. On the other hand, a set of twenty
pharmaceuticals was used for the enantiomer separations in non-aqueous CE
(NACE). Comparison between the results obtained with TBA7HDMS in aqueous
and non-aqueous CE were made. In addition, comparison between the results
obtained with TBA7HDMS and Na7HDMS in aqueous and non-aqueous CE were
made as well.
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Sanchez, Vindas Silvia Elena. « Non-aqueous, capillary electrophoretic separations of enantiomers with a charged cyclodextrin highly-soluble in organic solvents ». Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/2742.
Texte intégralRésumé :
The synthesis of the sodium salt of heptakis (2, 3-di-O-acetyl-6-O-sulfo)-β-cyclodextrin was modified to increase the isomeric purity to 98.5%. This salt was used to obtain the organic-solvent-soluble, single-isomer, charged tetrabutylammonium salt of heptakis (2, 3-di-O-acetyl-6-O-sulfo)-β-cyclodextrin. Its isomeric purity was higher than 99%, as determined by CE, and its structure was confirmed by NMR and ESI-MS analysis. The hydrophobic single-isomer cyclodextrin was utilized to separate the enantiomers of weak base analytes in aprotic media by capillary electrophoresis. The effective mobilities and separation selectivities follow trends observed with negatively charged cyclodextrins in amphiprotic solvents. The properties of the dissolved cyclodextrin are altered by its counter ion, thereby affecting the separations of enantiomers. The aprotic media allow the modification of the separation selectivity, since the binding strength of the enantiomers to the cyclodextrin is intermediate between that reported in aqueous and methanolic buffers.
Livres sur le sujet "Organic charge separators"
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Supercapacitor Technology. Materials Research Forum LLC, 2019. http://dx.doi.org/10.21741/9781644900499.
Texte intégralRésumé :
Supercapacitors are most interesting in the area of rechargeable battery based energy storage because they offer an unbeatable power density, quick charge/discharge rates and prolonged lifetimes in comparison to batteries. The book covers inorganic, organic and gel-polymer electrolytes, electrodes and separators used in different types of supercapacitors; with emphasis on material synthesis, characterization, fundamental electrochemical properties and most promising applications.
Chapitres de livres sur le sujet "Organic charge separators"
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Bunker, Bruce C., et William H. Casey. « The Ion Exchange Behavior of Oxides ». Dans The Aqueous Chemistry of Oxides. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780199384259.003.0017.
Texte intégralRésumé :
Oxides comprise the most common ion-exchange materials on our planet, with the clay minerals alone, formed by the weathering of rock, having a total mass of around 1025 g. This mass represents almost one-third of the total mass of Earth’s crust and is more than six times the mass of Earth’s oceans. These fine-grained ion exchange materials play a major role in mediating the concentrations of ionic species found in freshwater, groundwater, and our oceans (see Chapter 18). Oxide ion exchangers are also of critical importance in removing contaminants from the environment. Nowhere is this role more apparent than in the removal and sequestration of radioactive elements such as 137Cs, 90Sr, and 99Tc, which are serious hazards present in nuclear wastes. Oxide ion exchangers exhibit several properties that make them materials of choice for treating nuclear wastes, including high selectivity, enhanced stability to radiation damage relative to organic exchangers, and the potential as materials to be condensed further into solid waste after they are loaded with radioactive species. Oxide exchangers are extremely useful for extracting valuable cations from complex fluids, such as the lithium used in our highest energy density batteries. Ion exchange also represents a pathway for creating unique nanomaterials, with applications including battery separators, catalysts, optical materials, magnets, and materials for drug delivery. Oxides materials can exhibit exceptional properties as both cation and anion exchangers for a wide range of separation and water treatment technologies. Although the total ion-exchange capacity of an oxide is important for some applications, such as the deionization of water, separations require the use of oxides and hydroxides having the highest degree of ion-exchange selectivity. For selectivity, oxides must be designed with specific sites that exhibit a much higher affinity for one ion than any other, which requires much more sophistication than just generating a net charge. Here, we describe the key factors that control both the capacity and selectivity of inorganic ion exchangers, including (1) the role of acid–base reactions in controlling surface charge and ion-exchange capacity, (2) the role of local charge distributions in determining ion-exchange selectivity, and (3) the effect of shape and selective solvation on enhancing that selectivity.
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Harrison, Roger G., Paul W. Todd, Scott R. Rudge et Demetri P. Petrides. « Analytical Methods and Bench Scale Preparative Bioseparations ». Dans Bioseparations Science and Engineering. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195391817.003.0005.
Texte intégralRésumé :
The development of efficient and reliable processes for bioseparations is dependent on the availability of suitable analytical methods. This means it is important that work on analytical methodology for the bioproduct of interest starts at the very beginning of process development. Analytical studies are important throughout the development and scale up of the process, as changes can occur either to the product or to its associated impurities from what may be thought of as minor changes in the process. This chapter gives access to the vocabulary and techniques used in quality control and analytical development activities, starting with a description of specifications typically set for a pharmaceutical and the rationale behind them. Then, before discussing the assays themselves, we describe assay attributes, which can be measured and used to help not only the assay developer but also the biochemist and engineer responsible for developing downstream processes determine the usefulness and meaning of the assay. Finally, we turn to assays that are commonly applied in biotechnology, as they apply to biological activity, identity, and purity. These assays are the ultimate yardsticks by which the process is measured. Purification methods are developed for their ability to remove a contaminant from the product of interest, whether it is a related molecule, a contaminant related to a host organism, such as DNA or endotoxin, or a process contaminant, such as a residual solvent or water. Critical to understanding process performance is an understanding of how the assays that measure these contaminants have been developed, what the assay strengths and limitations are, and what they indicate and why. Electrophoresis and magnetic separation are two methods that are now used for the bench scale preparative purification of bioproducts, including living cells. The electrophoresis systems with the highest capacity are free-flow electrophoresis, density gradient electrophoresis, recycling free-flow isoelectric focusing, and rotating isoelectric focusing, and the principles of operation of these are discussed. The physical principles of magnetic separations are presented, as well as magnetic reagents and applications of magnetic separators.
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Autschbach, Jochen. « Hydrogen-like Atoms ». Dans Quantum Theory for Chemical Applications, 328–39. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190920807.003.0017.
Texte intégralRésumé :
This chapter shows how the electronic Schrodinger equation (SE) is solved for a hydrogen-like atom, i.e. an electron moving in the field of a fixed point-like nucleus with charge number Z. The hydrogen atom corresponds to Z = 1. The potential in atomic units is –Z/r, with r being the distance of the electron from the nucleus. The SE is not separable in Cartesian coordinates, but in spherical polar coordinates it separates into a radial equation and an angular momentum equation. The bound states have a total energy of –Z2/(2n2), with n = nr + ℓ being the principal quantum number (q.n.), ℓ = 0,1,2,… the angular momentum q.n., and nr = 1,2,3,… being a radial q.n. Each state for a given ℓ is 2ℓ+1-fold degenerate, with the components labelled by the projection q.n. mℓ. The wavefunctions for mℓ ≠ 0 are complex, but real linear combinations can be formed. This gives the atomic orbitals known from general and organic chemistry. Different ways of visualizing the real wavefunctions are discussed, e.g. as iso-surfaces.
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Hagel, Lars. « Separation on the basis of chemistry ». Dans Protein Purification Techniques. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780199636747.003.0011.
Texte intégralRésumé :
Most chromatographic separations are based on chemical interaction between the solute of interest or impurities to be removed and the separation medium. The exception is separations based upon physical properties such as size (e.g. size exclusion chromatography) or transport in a force field (e.g. electrochromatography). The chemical interaction may be weak (e.g. employing van der Waals forces) or very strong (e.g. involving formation of chemical bonds as in covalent chromatography). Whenever separation is based upon attractive forces between the solute and the separation medium, we talk about adsorption chromatography (also when the solute is merely retarded). The chemical interaction between the solute and the adsorbent (the chromatography medium) is governed by the surface properties of the solute and the adsorbent and is in most cases mediated by the mobile phase or additives to the mobile phase. Macromolecules such as proteins display a variety of properties and, ideally, a selected set of properties is utilized for obtaining the required selectivity (i.e. relative separation from other solutes) using a separation medium of complementary properties. This chapter briefly reviews the different types of forces of interaction between solutes and surfaces commonly employed for chromatographic purifications, important properties of solvents, and some basic surface chemical properties of proteins. This, together with a description of some common types of chromatography modes provides a basis for a rational selection of separation mechanism for the purification of proteins and the choice of mobile phase composition to regulate the relative influence of different interaction mechanisms. The separation mechanisms are focused to adsorptive modes with the exception of affinity chromatography which is discussed in Chapter 9. The different attractive forces acting between molecular and particle surfaces include (1): • dispersion forces • electrostatic dipole interactions • electron donor-acceptor forces • formation of covalent bonds All these forces are due to interactions between electric charges (permanent or induced). Dispersion, or London forces, are caused by induced dipole-induced dipole interactions and are thus classified as a non-specific interaction. This type of non-polar interaction is the dominant force promoting dissolution of non-polar solutes in organic solvents.
Actes de conférences sur le sujet "Organic charge separators"
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Rao, Vivek M., Marc-Olivier G. Delchini, Prashant K. Jain et Mohammad T. Bani Ahmad. « High-Performance Computing to Enable Next-Generation Low-Temperature Waste Heat Recovery ». Dans ASME 2020 Power Conference collocated with the 2020 International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/power2020-16374.
Texte intégralRésumé :
Abstract The Oak Ridge National Laboratory (ORNL), in collaboration with Eaton Corporation, has performed computational research and development to design an innovative, direct-contact heat exchanger (DCHE) that is optimized for a low-temperature organic Rankine cycle. A computational fluid dynamics (CFD) model of DCHE was developed in STAR-CCM+ which was later calibrated and validated against the experimental data from literature. The validated CFD model was used to develop an industry-relevant liquid-liquid direct-contact heat exchanger system with water and pentane working fluids. This work heavily relied on high-performance computing (HPC) resources to investigate multiple designs and to identify a baseline design. The innovative design consists of two chambers connected by a converging-diverging nozzle. Phase change for pentane, from liquid to vapor, occurs in the first chamber, whereas the second chamber serves as a separator. Outlets in the second chamber are staggered to prevent entrainment of the liquid water by the gaseous pentane. CFD results confirm that the design behaves as expected and the addition of baffles enhances mixing and heat transfer for higher flow rates while preventing entrainment of gaseous pentane by the liquid water.
Rapports d'organisations sur le sujet "Organic charge separators"
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Borch, Thomas, Yitzhak Hadar et Tamara Polubesova. Environmental fate of antiepileptic drugs and their metabolites : Biodegradation, complexation, and photodegradation. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7597927.bard.
Texte intégralRésumé :
Many pharmaceutical compounds are active at very low doses, and a portion of them regularly enters municipal sewage systems and wastewater-treatment plants following use, where they often do not fully degrade. Two such compounds, CBZ and LTG, have been detected in wastewater effluents, surface waters, drinking water, and irrigation water, where they pose a risk to the environment and the food supply. These compounds are expected to interact with organic matter in the environment, but little is known about the effect of such interactions on their environmental fate and transport. The original objectives of our research, as defined in the approved proposal, were to: Determine the rates, mechanisms and products of photodegradation of LTG, CBZ and selected metabolites in waters exposed to near UV light, and the influence of DOM type and binding processes on photodegradation. Determine the potential and pathways for biodegradation of LTG, CBZ and selected metabolites using a white rot fungus (Pleurotusostreatus) and ADP, and reveal the effect of DOM complexation on these processes. Reveal the major mechanisms of binding of LTG, CBZ and selected metabolites to DOM and soil in the presence of DOM, and evaluate the effect of this binding on their photodegradation and/or biodegradation. We determined that LTG undergoes relatively slow photodegradation when exposed to UV light, and that pH affects each of LTG’s ability to absorb UV light, the efficiency of the resulting reaction, and the identities of LTG’sphotoproducts (t½ = 230 to 500 h during summer at latitude 40 °N). We observed that LTG’sphotodegradation is enhanced in the presence of DOM, and hypothesized that LTG undergoes direct reactions with DOM components through nucleophilic substitution reactions. In combination, these data suggest that LTG’s fate and transport in surface waters are controlled by environmental conditions that vary with time and location, potentially affecting the environment and irrigation waters. We determined that P. ostreatusgrows faster in a rich liquid medium (glucose peptone) than on a natural lignocellulosic substrate (cotton stalks) under SSF conditions, but that the overall CBZ removal rate was similar in both media. Different and more varied transformation products formed in the solid state culture, and we hypothesized that CBZ degradation would proceed further when P. ostreatusand the ᵉⁿᶻʸᵐᵃᵗⁱᶜ ᵖʳᵒᶠⁱˡᵉ ʷᵉʳᵉ ᵗᵘⁿᵉᵈ ᵗᵒ ˡⁱᵍⁿⁱⁿ ᵈᵉᵍʳᵃᵈᵃᵗⁱᵒⁿ. ᵂᵉ ᵒᵇˢᵉʳᵛᵉᵈ ¹⁴C⁻Cᴼ2 ʳᵉˡᵉᵃˢᵉ ʷʰᵉⁿ ¹⁴C⁻ᶜᵃʳᵇᵒⁿʸˡ⁻ labeled CBZ was used as the substrate in the solid state culture (17.4% of the initial radioactivity after 63 days of incubation), but could not conclude that mineralization had occurred. In comparison, we determined that LTG does not degrade in agricultural soils irrigated with treated wastewater, but that P. ostreatusremoves up to 70% of LTG in a glucose peptone medium. We detected various metabolites, including N-oxides and glycosides, but are still working to determine the degradation pathway. In combination, these data suggest that P. ostreatuscould be an innovative and effective tool for CBZ and LTG remediation in the environment and in wastewater used for irrigation. In batch experiments, we determined that the sorption of LTG, CBZ and selected metabolites to agricultural soils was governed mainly by SOM levels. In lysimeter experiments, we also observed LTG and CBZ accumulation in top soil layers enriched with organic matter. However, we detected CBZ and one of its metabolites in rain-fed wheat previously irrigated with treated wastewater, suggesting that their sorption was reversible, and indicating the potential for plant uptake and leaching. Finally, we used macroscale analyses (including adsorption/desorption trials and resin-based separations) with molecular- level characterization by FT-ICR MS to demonstrate the adsorptive fractionation of DOM from composted biosolids by mineral soil. This suggests that changes in soil and organic matter types will influence the extent of LTG and CBZ sorption to agricultural soils, as well as the potential for plant uptake and leaching.