The Experts below are selected from a list of 13314 Experts worldwide ranked by ideXlab platform
Michael Hirscher - One of the best experts on this subject based on the ideXlab platform.
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highly effective hydrogen Isotope Separation through dihydrogen bond on cu i exchanged zeolites well above liquid nitrogen temperature
Chemical Engineering Journal, 2020Co-Authors: Linda Zhang, Renjin Xiong, Wenhua Luo, Tao Tang, Ge Sang, Changan Chen, Xiayan Yan, Jinfan Chen, Michael HirscherAbstract:Abstract Hydrogen Isotope Separation under moderate conditions with high selectivity remains a huge challenge due to the identical physicochemical properties of the Isotopes. Here, we present zeolite materials with an excellent thermal stability and highly selective for hydrogen Isotope Separation through dihydrogen bond on ion-exchanged Cu(I) centers. Thermal desorption spectroscopy (TDS) measurements show that hydrogen Isotope Separation and enrichment can be carried out in a technologically favorable temperature range from liquid nitrogen temperature to near room temperature, and a D2/H2 selectivity of 24.9 for the Cu(I)-ZSM-5 zeolite is achieved, which is the highest selectivity value ever measured at 100 K. In addition, 99.6% of deuterium can be enriched through only three adsorption/desorption cycles from a mixture with a deuterium concentration of 2.5%. Structural characterization and density functional theory calculations reveal that the high hydrogen Isotope selectivity of Cu(I)-ZSM-5 zeolite can be attributed to the strong chemical affinity through dihydrogen bond on Cu(I) sites with a large Isotope effect in zero-point energy (ΔEZPE) and adsorption enthalpy (ΔH), resulting in hydrogen Isotope Separation and enrichment efficiently through low-cost materials in a technological scale.
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exploiting dynamic opening of apertures in a partially fluorinated mof for enhancing h2 desorption temperature and Isotope Separation
Journal of the American Chemical Society, 2019Co-Authors: Linda Zhang, Seohyeon Jee, Jaewoo Park, Minji Jung, Dirk Wallacher, Alexandra Franz, Wonjoo Lee, Minyoung Yoon, Kyung Min Choi, Michael HirscherAbstract:Deuterium has been recognized as an irreplaceable element in industrial and scientific research. However, hydrogen Isotope Separation still remains a huge challenge due to the identical physicochem...
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selective hydrogen Isotope Separation via breathing transition in mil 53 al
Journal of the American Chemical Society, 2017Co-Authors: Jin Yeong Kim, Linda Zhang, Michael Hirscher, Rafael Balderasxicohtencatl, Jaewoo Park, Hoi Ri MoonAbstract:Breathing of MIL-53(Al), a flexible metal–organic framework (MOF), leads to dynamic changes as narrow pore (np) transitions to large pore (lp). During the flexible and reversible transition, the pore apertures are continuously adjusted, thus providing the tremendous opportunity to separate mixtures of similar-sized and similar-shaped molecules that require precise pore tuning. Herein, for the first time, we report a strategy for effectively separating hydrogen Isotopes through the dynamic pore change during the breathing of MIL-53(Al), a representative of flexible MOFs. The experiment shows that the selectivity for D2 over H2 is strongly related to the state of the pore structure of MIL-53(Al). The highest selectivity (SD2/H2 = 13.6 at 40 K) was obtained by optimizing the exposure temperature, pressure, and time to systematically tune the pore state of MIL-53(Al).
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exploiting diffusion barrier and chemical affinity of metal organic frameworks for efficient hydrogen Isotope Separation
Journal of the American Chemical Society, 2017Co-Authors: Jin Yeong Kim, Linda Zhang, Sung Gu Kang, Michael Hirscher, Rafael Balderasxicohtencatl, Hoi Ri MoonAbstract:Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as Isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern Separation technology. However, current commercial approaches suffer from extremely low Separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale Separation technique. Herein, we report a highly effective hydrogen Isotope Separation system based on metal–organic frameworks (MOFs) having the highest reported Separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sit...
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hydrogen Isotope Separation in metal organic frameworks kinetic or chemical affinity quantum sieving
Microporous and Mesoporous Materials, 2015Co-Authors: Ievgeniia Savchenko, Andreas Mavrandonakis, Thomas Heine, Julia Teufel, Michael HirscherAbstract:Recently we reported hydrogen Isotope Separation by quantum sieving in metal-organic framework MFU-4, a framework exhibiting gates of about the same size as the molecular radii of D2 and H2. Due to its smaller effective particle size, D2 penetrates preferentially through the framework, resulting in remarkable selectivity. Surprisingly, MFU-4l, a material of very similar composition, but with substantially larger gate openings, shows appreciable hydrogen isotopologue selectivity. This selectivity occurs at low temperature and is smaller compared to earlier reported CPO-27, a framework exhibiting open metal sites. We show that this is caused by different adsorption enthalpies which are the result of quantum effects. It turns out that two independent hydrogen Isotope Separation mechanisms have been reported for MOFs: while kinetic quantum sieving works at cryogenic temperatures for materials with small pores, different adsorption energies allow chemical affinity quantum sieving. This effect is maximized by strong adsorption centers, which allow high selectivity at high temperatures (100 K and above), and is more appropriate for the rational design of Isotope Separation membranes.
Linda Zhang - One of the best experts on this subject based on the ideXlab platform.
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highly effective hydrogen Isotope Separation through dihydrogen bond on cu i exchanged zeolites well above liquid nitrogen temperature
Chemical Engineering Journal, 2020Co-Authors: Linda Zhang, Renjin Xiong, Wenhua Luo, Tao Tang, Ge Sang, Changan Chen, Xiayan Yan, Jinfan Chen, Michael HirscherAbstract:Abstract Hydrogen Isotope Separation under moderate conditions with high selectivity remains a huge challenge due to the identical physicochemical properties of the Isotopes. Here, we present zeolite materials with an excellent thermal stability and highly selective for hydrogen Isotope Separation through dihydrogen bond on ion-exchanged Cu(I) centers. Thermal desorption spectroscopy (TDS) measurements show that hydrogen Isotope Separation and enrichment can be carried out in a technologically favorable temperature range from liquid nitrogen temperature to near room temperature, and a D2/H2 selectivity of 24.9 for the Cu(I)-ZSM-5 zeolite is achieved, which is the highest selectivity value ever measured at 100 K. In addition, 99.6% of deuterium can be enriched through only three adsorption/desorption cycles from a mixture with a deuterium concentration of 2.5%. Structural characterization and density functional theory calculations reveal that the high hydrogen Isotope selectivity of Cu(I)-ZSM-5 zeolite can be attributed to the strong chemical affinity through dihydrogen bond on Cu(I) sites with a large Isotope effect in zero-point energy (ΔEZPE) and adsorption enthalpy (ΔH), resulting in hydrogen Isotope Separation and enrichment efficiently through low-cost materials in a technological scale.
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exploiting dynamic opening of apertures in a partially fluorinated mof for enhancing h2 desorption temperature and Isotope Separation
Journal of the American Chemical Society, 2019Co-Authors: Linda Zhang, Seohyeon Jee, Jaewoo Park, Minji Jung, Dirk Wallacher, Alexandra Franz, Wonjoo Lee, Minyoung Yoon, Kyung Min Choi, Michael HirscherAbstract:Deuterium has been recognized as an irreplaceable element in industrial and scientific research. However, hydrogen Isotope Separation still remains a huge challenge due to the identical physicochem...
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barely porous organic cages for hydrogen Isotope Separation
Science, 2019Co-Authors: Ming Liu, Linda Zhang, Marc A Little, Venkat Kapil, Michele Ceriotti, Siyuan Yang, Lifeng Ding, Daniel Holden, Rafael Balderasxicohtencatl, Rob ClowesAbstract:The Separation of hydrogen Isotopes for applications such as nuclear fusion is a major challenge. Current technologies are energy intensive and inefficient. Nanoporous materials have the potential to separate hydrogen Isotopes by kinetic quantum sieving, but high Separation selectivity tends to correlate with low adsorption capacity, which can prohibit process scale-up. In this study, we use organic synthesis to modify the internal cavities of cage molecules to produce hybrid materials that are excellent quantum sieves. By combining small-pore and large-pore cages together in a single solid, we produce a material with optimal Separation performance that combines an excellent deuterium/hydrogen selectivity (8.0) with a high deuterium uptake (4.7 millimoles per gram).
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selective hydrogen Isotope Separation via breathing transition in mil 53 al
Journal of the American Chemical Society, 2017Co-Authors: Jin Yeong Kim, Linda Zhang, Michael Hirscher, Rafael Balderasxicohtencatl, Jaewoo Park, Hoi Ri MoonAbstract:Breathing of MIL-53(Al), a flexible metal–organic framework (MOF), leads to dynamic changes as narrow pore (np) transitions to large pore (lp). During the flexible and reversible transition, the pore apertures are continuously adjusted, thus providing the tremendous opportunity to separate mixtures of similar-sized and similar-shaped molecules that require precise pore tuning. Herein, for the first time, we report a strategy for effectively separating hydrogen Isotopes through the dynamic pore change during the breathing of MIL-53(Al), a representative of flexible MOFs. The experiment shows that the selectivity for D2 over H2 is strongly related to the state of the pore structure of MIL-53(Al). The highest selectivity (SD2/H2 = 13.6 at 40 K) was obtained by optimizing the exposure temperature, pressure, and time to systematically tune the pore state of MIL-53(Al).
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exploiting diffusion barrier and chemical affinity of metal organic frameworks for efficient hydrogen Isotope Separation
Journal of the American Chemical Society, 2017Co-Authors: Jin Yeong Kim, Linda Zhang, Sung Gu Kang, Michael Hirscher, Rafael Balderasxicohtencatl, Hoi Ri MoonAbstract:Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as Isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern Separation technology. However, current commercial approaches suffer from extremely low Separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale Separation technique. Herein, we report a highly effective hydrogen Isotope Separation system based on metal–organic frameworks (MOFs) having the highest reported Separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sit...
Michael L. Free - One of the best experts on this subject based on the ideXlab platform.
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high efficiency lithium Isotope Separation in an electrochemical system with 1 butyl 3 methylimidazolium dicyanamide 1 ethyl 3 methylimidazolium bis trifluoromethylsulfonyl imide and diethyl carbonate as the solvents
Separation and Purification Technology, 2020Co-Authors: Zongliang Zhang, Prashant K. Sarswat, Arun Murali, Michael L. FreeAbstract:Abstract Traditional Li Isotope Separation methods such as the column exchange process are environmentally hazardous because of the mercury involved. In this research, a high-efficiency Li Isotope Separation technique with a Separation coefficient of 1.054 was developed based on the diffusion and migration of Li Isotopes in various solvents. In many solutions, the difference in the diffusion coefficient is small; therefore, the Separation effect is not satisfactory. However, due to their unique physical and chemical properties, ionic liquids such as 1-Butyl-3-methylimidazolium dicyanamide and 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and some organic solvents such as diethyl carbonate show higher differences in Li Isotope diffusion coefficients and mobilities, hence they can be used to achieve the efficient Separation of Li Isotopes. The Isotope Separation with four Li salts (LiBF4, LiCl, LiBr, and LiI) in the three solvents was investigated utilizing these differences. The results show that some Li salts can achieve excellent Separation effect in ionic liquids and organic solvents. The corresponding model simulation results also show that the Separation effect increases with the increase of the diffusion coefficient difference, and the higher Separation coefficient may be realized by searching for the solvent with more differences in the Li Isotope diffusion coefficients and mobilities.
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high efficiency lithium Isotope Separation by electrochemical deposition and intercalation with electrochemical Isotope effect in propylene carbonate and bmim dca ionic liquid
Electrochimica Acta, 2020Co-Authors: Zongliang Zhang, Prashant K. Sarswat, Arun Murali, Michael L. FreeAbstract:Abstract Li Isotopes are of great importance in the nuclear industry and are generally produced by the environmentally hazardous column exchange process. Many Separation techniques have been proposed to develop an environmentally-friendly and cost-effective Separation method. Among all the proposed methods, the electrochemical deposition and intercalation method is of promising application in the future. However, no industrialization attempts have been made because of the lack of thorough research in this field. In this paper, the Li Isotope Separation tests were conducted with the electrochemical deposition and intercalation method and the experimental setup proposed in this research. To have a comprehensive understanding of the factors influencing performance, the effects of solvent and cathodic substrate were investigated with LiBF4 deposition tests on four substrates in two solvents. Experimental results show that the Separation coefficient from the graphite substrate is consistent with the literature reported value. Other combinations of substrates and solvents yield better Separation coefficients. For most of them, the Separation coefficient may reach 1.09–1.10, which is the highest Separation coefficient observed in various Li Isotope Separation tests in this study as well as in the literature reported to the best of the authors’ knowledge. Moreover, a Separation coefficient of 1.20 was achieved with the Ni-PC system.
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li Isotopes concentration flux investigation under conditions of diffusion and electric field assisted migration
Vacuum, 2018Co-Authors: Zongliang Zhang, Prashant K. Sarswat, Michael L. FreeAbstract:Abstract Due to the variety of applications of the Isotopes in science and engineering as well as their strategic importance in national security, efficient and purity production is essential. It is important to note that the mixture of the two Isotopes 6Li and 7Li have a natural abundances of ∼7.5% and 92.5%, respectively. 7Li in its hydroxide form is often utilized in pressurized water reactors of the power plant. One possibility of 7Li enrichment can be the application of diffusion and electric field assisted Separation in liquids or gels. In this research, a preliminary study has been conducted using COMSOL Multiphysics simulation package, in order to simulate the concentration gradients of two ions namely 7Li+ and 6Li+. In the model, both diffusion and migration conditions were implemented and associated effects of the Isotope Separation were monitored. Apart from time-dependent concentrations of the different Isotopes (their respective ions), the contour maps were also presented, including the zone of maximum efficiency for different time as well as initial concentration. The results from the model can be utilized for designing actual Isotope Separation setup and appropriate timing for sample collection.
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measurements and simulations of lithium Isotopes concentration fluxes during electrolytic lithium 7 enrichment
Symposium on Industrial Electrochemistry and Electrochemical Engineering General Session - 233rd ECS Meeting, 2018Co-Authors: Zongliang Zhang, Jaron Wallace, Prashant K. Sarswat, Michael L. FreeAbstract:High purity lithium Isotopes have significant applications in nuclear industry and other related fields. Many of the ongoing lithium Isotope Separation processes have environmental issues, and the use of mercury is one of them. As part of the development of a new lithium Isotope Separation process, the effect of the concentration gradient and electric field were studied using experimental electrochemical cells and a recently built numerical model. Samples from the experimental test were collected and then purified by the ion exchange chromatography for ICP-MS analysis. The concentration and Isotopes ratio measured with ICP-MS indicated reasonable time dependence behavior. The data confirmed that the difference in the diffusion and migration rate of the Isotopes facilitates Li Isotope Separations. Furthermore, the potentiostatic scanning tests were conducted, and they revealed the time it takes to achieve Separation with diffusion and migration. Finally, the electrochemical model with mass transfer predicted the Isotopes ratio distribution for comparison with the experimental results. The mass transfer of Li Isotopes confirmed the excellent Separation potential using the electrochemical approach.
Hoi Ri Moon - One of the best experts on this subject based on the ideXlab platform.
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Elucidation of Diffusivity of Hydrogen Isotopes in Flexible MOFs by Quasi-Elastic Neutron Scattering
'Wiley', 2021Co-Authors: Jung Minji, Park Jaewoo, Muhammad Raeesh, Kim, Jin Yeong, Grzimek Veronika, Russina Margarita, Hoi Ri Moon, Park, Jitae T., Oh HyunchulAbstract:Kinetic-quantum-sieving-assisted H-2:D-2 Separation in flexible porous materials is more effective than the currently used energy-intensive cryogenic distillation and girdle-sulfide processes for Isotope Separation. It is believed that material flexibility results in a pore-breathing phenomenon under the influence of external stimuli, which helps in adjusting the pore size and gives rise to the optimum quantum-sieving phenomenon at each stage of gas Separation. However, only a few studies have investigated kinetic-quantum-sieving-assisted Isotope Separation using flexible porous materials. In addition, no reports are available on the microscopic observation of isotopic molecular transportation during the Separation process under dynamic transition. Here, the experimental observation of a significantly faster diffusion of deuterium than hydrogen in a flexible pore structure, even at high temperatures, through quasi-elastic neutron scattering, is reported. Unlike rigid structures, the extracted diffusion dynamics of hydrogen Isotopes within flexible frameworks show that the diffusion difference between the Isotopes increases with an increase in temperature. Owing to this unique inverse trend, a new strategy is suggested for achieving higher operating temperatures for efficient Isotope Separation utilizing a flexible metal-organic framework system
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Hydrogen Separation and purification with MOF-based materials
'Royal Society of Chemistry (RSC)', 2021Co-Authors: Lim Dae-woon, Ha Junsu, Oruganti Yasaswini, Hoi Ri MoonAbstract:Hydrogen (H-2) has been receiving considerable attention as a promising future energy source owing to its high energy density and eco-friendly features. Nonetheless, H-2 production, utilization, and storage involve many technical challenges, which must be overcome to realise a sustainable hydrogen economy. In particular, the high purity of H-2 is important for its utilization as a clean fuel, so energy- and cost-efficient purification processes and materials are essential. In addition, the Separation of valuable hydrogen Isotopes such as deuterium (D) and tritium (T), which have similar physicochemical properties, is not only challenging but also significant because of the high demand for these Isotopes in industrial, medical, and scientific research but their low natural occurrence. Recently, porous crystalline metal-organic frameworks (MOFs) have emerged as a promising candidate for H-2 purification and Isotope Separation owing to their designable porosity and functionality, which affect their molecular sieving effect and the kinetic and/or chemical affinity quantum sieving effects. Their rational design and synthesis with a judicious choice of metal ions and organic ligands provide the desired properties and functionality, resulting in a controlled structural topology, pore size, shape, and surface polarity. This review is intended to provide a comprehensive understanding of the fundamental theories and strategies for MOF-based H-2 Separation and purification, including hydrogen Isotope Separation with representative examples
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selective hydrogen Isotope Separation via breathing transition in mil 53 al
Journal of the American Chemical Society, 2017Co-Authors: Jin Yeong Kim, Linda Zhang, Michael Hirscher, Rafael Balderasxicohtencatl, Jaewoo Park, Hoi Ri MoonAbstract:Breathing of MIL-53(Al), a flexible metal–organic framework (MOF), leads to dynamic changes as narrow pore (np) transitions to large pore (lp). During the flexible and reversible transition, the pore apertures are continuously adjusted, thus providing the tremendous opportunity to separate mixtures of similar-sized and similar-shaped molecules that require precise pore tuning. Herein, for the first time, we report a strategy for effectively separating hydrogen Isotopes through the dynamic pore change during the breathing of MIL-53(Al), a representative of flexible MOFs. The experiment shows that the selectivity for D2 over H2 is strongly related to the state of the pore structure of MIL-53(Al). The highest selectivity (SD2/H2 = 13.6 at 40 K) was obtained by optimizing the exposure temperature, pressure, and time to systematically tune the pore state of MIL-53(Al).
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exploiting diffusion barrier and chemical affinity of metal organic frameworks for efficient hydrogen Isotope Separation
Journal of the American Chemical Society, 2017Co-Authors: Jin Yeong Kim, Linda Zhang, Sung Gu Kang, Michael Hirscher, Rafael Balderasxicohtencatl, Hoi Ri MoonAbstract:Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as Isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern Separation technology. However, current commercial approaches suffer from extremely low Separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale Separation technique. Herein, we report a highly effective hydrogen Isotope Separation system based on metal–organic frameworks (MOFs) having the highest reported Separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sit...
Yasuhiko Fujii - One of the best experts on this subject based on the ideXlab platform.
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zinc Isotope Separation by ligand exchange chromatography using cation exchange resin
Journal of ion exchange, 2002Co-Authors: Yasutoshi Ban, Masao Aida, Masao Nomura, Yasuhiko FujiiAbstract:Zinc Isotope effects in Zn-EDTA ligand exchange were studied by using a macroporous strongly acidic cation exchange resin packed in columns. Both front and rear boundaries of a zinc band were sharp after 28m migration at 60°C. Zinc Isotope ratios of 66Zn/64Zn were measured by a mass spectrometer with surface ionization source. The enrichment of the heavier Isotope, 66Zn, was found at the front band boundary region. Isotope Separation coefficient per unit mass, e/ΔM, and height equivalent to a theoretical plate were calculated as 8.0×10-5 and 0.9mm, respectively. Discussion is extended to the profile analysis on the chromatographic Isotope Separation. The results were compared with previously reported Isotope effects in the ligand exchange reaction of other elements.
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flow rate dependence of the height equivalent to a theoretical plate in nitrogen Isotope Separation by displacement chromatography
Journal of Chromatography A, 1998Co-Authors: Masao Ohwaki, Yasuhiko Fujii, Makoto HasegawaAbstract:The effect of flow-rate in nitrogen Isotope Separation was studied for a wide range of fluid velocities using porous microreticular cation-exchange resin. The displacement chromatography was conducted from a band velocity of 6.3×10−3 to 12.5 cm/min (or Reynolds number of 15–30 000). A sharp adsorbed ammonium band was maintained even at a band velocity of 12.5 cm/min; on the other hand, tilted and/or channeled boundaries of the band are enlarged in the low-flow-rate region. The effect of fluid velocity on the height equivalent to a theoretical plate (HETP) of Isotope Separation was evaluated in terms of Reynolds number. In the present work, the HETP is proportional to the square-root of the band velocity in the turbulent flow regime and inversely proportional to the fluid velocity in the laminar flow regime due to the longitudinal mixing which is caused by tilting and/or channeling at the band boundary.
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mass dependence of uranium Isotope effects in the u iv u vi exchange reaction
Journal of the American Chemical Society, 1996Co-Authors: Masao Nomura, Nobuhiko Higuchi, Yasuhiko FujiiAbstract:Isotope Separation of {sup 233}U by anion exchange chromatography based on the U(IV)-U(VI) exchange is studied. After long-distance migration, {sup 233}U enrichment is observed at the rear band boundary. To examine the Isotope effects of {sup 233}U, {sup 234}U, and {sup 238}U, three-Isotope plots of local enrichment factors are constructed for the Isotopes contained in sample fractions of the eluted uranium band. The results clearly show an anomalous mass dependence for {sup 233}U. We previously reported that the even-mass nuclides {sup 232}U, {sup 234}U, {sup 236}U, and {sup 238}U show a regular mass-dependence in their Isotope Separation behaviors, while {sup 235}U does not fall on the same line. The Isotope effects of the odd-mass nuclides {sup 233}U and {sup 235}U deviate from the linear mass dependence observed among the even-mass nuclides. The Isotope effects observed in chemical exchange are shown to be closely related to the Isotope shifts in the atomic spectra of uranium Isotopes. 21 refs., 4 figs., 3 tabs.