A study of capillary discharge lamps in Ar–Hg and Xe–Hg mixtures

Denisova, N. V.; Gavare, Zanda; Rēvalde, Gita; Skudra, Ja; Veilande, Rita

doi:10.1088/0022-3727/44/15/155201

Cited by 9 publications

(6 citation statements)

References 16 publications

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“…The separation of Xe and Kr is of great interest and importance industrially. For example, high-purity Xe is a valuable commodity and widely used in semiconductors, electronics, medical, space, lighting, and gas lasers, while the high-purity Kr can be not only used for making gas tracer but also applied for “kryptonation” of materials, that is, utilized to measure the temperature distribution of turbine blades in aircraft engines, determine the best structure of internal combustion engines, and analyze the ultrafine cracks in turbine blades that cannot be detected by other methods. − Commercially, high-purity Xe and Kr are almost totally acquired as byproducts in cryogenic air separation, of which a 20/80 v/v mixture of Xe/Kr is obtained and must undergo further separation to produce pure Xe or Kr. Currently, cryogenic distillation is the most mature technology to separate Xe and Kr from air and nuclear waste reprocessing but which is excessively energy-intensive.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Computational Screening of Metal–Organic Frameworks for Kr/Xe Adsorption Separation: A Structure–Property Relationship-Based Screening Strategy

Lin

Xue-lian

Heng

et al. 2021

ACS Appl. Mater. Interfaces

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The separation of radioactive noble gases, such as Xe and Kr, has attracted special attention in the context of used nuclear fuel (UNF). In this study, 180 metal–organic frameworks (MOFs) formally used for selective adsorptions of ethane and ethylene, with a similar kinetic diameter to Kr and Xe, were initially screened for the Kr/Xe separation using the grand canonical Monte Carlo (GCMC) method. Then, the structure–adsorption property relationships were generalized, that is, the MOFs of higher Kr/Xe selectivity are with the porosity at 0.2–0.4 and the ratio of the largest cavity diameter/pore limiting diameter at 1.0–2.4. Based on the relationships, six reported MOFs with large Kr uptakes and Kr/Xe selectivities were experimentally screened out and validated by GCMC simulations within the CoRE-MOF database, which are higher than most reported MOFs under conditions pertinent to nuclear fuel reprocessing of an 80/20 v/v mixture of Kr/Xe at normal temperature and pressure. Further simulations reveal that higher Kr uptakes and Kr/Xe selectivities of six MOFs result from the confinement effect of the pores. Molecular dynamic simulations showed that the six MOFs are ideal membrane separation materials of Kr from Xe, which are driven by adsorption and diffusion. Analyses of electronic structure-based density functional theory calculations showed that the main interaction between Kr and the six MOFs is van der Waals force dominated by dispersion and induction interactions. Therefore, the generalized structure–adsorption property relationships may assist the screening of MOFs for the separation and production of Kr/Xe from UNF industrially.

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Section: Introductionmentioning

confidence: 99%

Multiscale Computational Screening of Metal–Organic Frameworks for Kr/Xe Adsorption Separation: A Structure–Property Relationship-Based Screening Strategy

Lin

Xue-lian

Heng

et al. 2021

ACS Appl. Mater. Interfaces

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“…ads MOF gas MOF gas (7) where E MOF+gas , E MOF , and E gas are energies of MOFs with adsorbed gas, bare MOFs without gas, and isolated Kr or Xe, respectively. This was calculated by using the DMol 353 module incorporated in the Materials Studio 2019 package.…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

“…Thus, the high-level radioactive nuclear waste of Kr and Xe must be well recycled before nuclear energy can be widely used. , On the one hand, high-purity Kr can be used to not only manufacture gas tracers but also measure the temperature distribution of turbine blades of aircraft engines and analyze ultrafine cracks in turbine blades . On the other hand, high-purity Xe is widely used in medical imaging, commercial lighting, neuroprotection, anesthesia, and other fields. – Industrially, the Kr/Xe mixture with a ratio of 80:20 is produced by processing air or nuclear waste as a byproduct, and then pure Kr and Xe are separated from this mixture by cryogenic distillation, which is an energy-intensive technology.…”

Section: Introductionmentioning

confidence: 99%

Combination of High-Throughput Screening and Assembly to Discover Efficient Metal–Organic Frameworks on Kr/Xe Adsorption Separation

Du,

Xiao,

Wang

et al. 2023

J. Phys. Chem. B

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Recycling Kr and Xe from used nuclear fuel (UNF) is conducive to regenerating economy and protecting the environment, and it is urgent to screen or design high-performance cutting-edge metal−organic framework (MOF) materials for Kr/ Xe adsorption separation. After grand canonical Monte Carlo (GCMC) simulations of Kr/Xe adsorption separation on 11,000 frameworks in CoRE MOFs (2019), the important structure− adsorption property relationship (SAPR) was induced; that is, the porosity (φ) at 0.30−0.40, LCD/PLD at 1.00−1.49, density (ρ) range between 1.20 and 2.30 g/cm 3 , and PLD at 2.40−3.38 Å can be utilized to screen for high-performance G-MOFs and hMOFs. In addition, the key "genes" (metal nodes and linkers) of MOFs determining the Kr/Xe adsorption separation were data-mined by a machine learning technique, which were assembled into novel MOFs. After comprehensive consideration of thermal stability and the adsorbent performance score (APS), eight promising MOFs on Kr/Xe separation with the APS more than 1290.89 were screened out and assembled, which are better than most of the reported frameworks. Note that the adsorption isotherms of these MOFs on Kr and Xe belong to type I curve with the thermodynamic equilibrium mechanism on Kr/Xe based on the confinement effect. Furthermore, according to the electronic structure calculations of the independent gradient model based on Hirshfeld partition (IGMH) and energy decomposition analysis, it is found that the interactions between guests and frameworks are vdW forces with dominant induction energy (Eind). In addition, the electrostatic potential gradients of frameworks are generally linearly negative correlated with Kr uptakes. Therefore, both the geometrical and electronic structures dominate the adsorption separation performance on Kr/Xe. Interestingly, these eight MOFs are also suitable for the separation of CH 4 /H 2 with considerable selectivities and CH 4 uptakes of up to 2566.67 and 3.04 mmol/g, respectively. Herein, the accurately constructed SAPR and material genomics strategy should be helpful for the experimental discovery of novel MOFs on Kr/Xe separation experimentally.

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“…The noble gases xenon (Xe) and krypton (Kr) are widely used in industrial production and daily life due to their special physical and chemical properties. For instance, Xe can be used in commercial lighting, , medical imaging, anesthesia, , and neuroprotection, , while Kr is widely used in the electronics industry, electric light source industry, as well as in gas lasers and plasma streams. The content of xenon and krypton in the atmosphere just covers a minor proportion, and they mainly exist in used nuclear fuel (UNF) with a Xe/Kr ratio of 20:80.…”

Section: Introductionmentioning

confidence: 99%

XGBoost: An Optimal Machine Learning Model with Just Structural Features to Discover MOF Adsorbents of Xe/Kr

Heng

Jiang²,

Yan

et al. 2021

ACS Omega

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The inert gases Xe and Kr mainly exist in the used nuclear fuel (UNF) with the Xe/Kr ratio of 20:80, which it is difficult to separate. In this work, based on the G-MOFs database, high-throughput computational screening for metal–organic frameworks (MOFs) with high Xe/Kr adsorption selectivity was performed by combining grand canonical Monte Carlo (GCMC) simulations and machine learning (ML) technique for the first time. From the comparison of eight classical ML models, it is found that the XGBoost model with seven structural descriptors has superior accuracy in predicting the adsorption and separation performance of MOFs to Xe/Kr. Compared with energetic or electronic descriptors, structural descriptors are easier to obtain. Note that the determination coefficients R 2 of the generalized model for the Xe adsorption and Xe/Kr selectivity are very close to 1, at 0.951 and 0.973, respectively. In addition, 888 and 896 MOFs have been successfully predicted by the XGBoost model among the top 1000 MOFs in adsorption capacity and selectivity by GCMC simulation, respectively. According to the feature engineering of the XGBoost model, it is shown that the density (ρ), porosity (ϕ), pore volume (Vol), and pore limiting diameter (PLD) of MOFs are the key features that affect the Xe/Kr adsorption property. To test the generalization ability of the XGBoost model, we also tried to screen MOF adsorbents on the CO 2 /CH 4 mixture, it is found that the prediction performance of XGBoost is also much better than that of the traditional machine learning models although with the unbalanced data. Note that the dimension of features of MOFs is low while the quantity of MOF samples in database is very large, which is suitable for the prediction by model such as XGBoost to search the global minimum of cost function rather than the model involving feature creation. The present study represents the first report using the XGBoost algorithm to discover the MOF adsorbates.

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A study of capillary discharge lamps in Ar–Hg and Xe–Hg mixtures

Cited by 9 publications

References 16 publications

Multiscale Computational Screening of Metal–Organic Frameworks for Kr/Xe Adsorption Separation: A Structure–Property Relationship-Based Screening Strategy

Multiscale Computational Screening of Metal–Organic Frameworks for Kr/Xe Adsorption Separation: A Structure–Property Relationship-Based Screening Strategy

Combination of High-Throughput Screening and Assembly to Discover Efficient Metal–Organic Frameworks on Kr/Xe Adsorption Separation

XGBoost: An Optimal Machine Learning Model with Just Structural Features to Discover MOF Adsorbents of Xe/Kr

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