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Ohkubo T, Takei A, Tachi Y, Fukatsu Y, Deguchi K, Ohki S, Shimizu T. New Approach To Understanding the Experimental 133Cs NMR Chemical Shift of Clay Minerals via Machine Learning and DFT-GIPAW Calculations. J Phys Chem A 2023; 127:973-986. [PMID: 36657157 DOI: 10.1021/acs.jpca.2c08880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Structural determination of adsorbed atoms on layered structures such as clay minerals is a complex subject. Radioactive cesium (Cs) is an important element for environmental conservation, so it is vital to understand its adsorption structure on clay. The nuclear magnetic resonance (NMR) parameters of 133Cs, which can be determined from solid-state NMR experiments, are sensitive to the local neighboring structures of adsorbed Cs. However, determining the Cs positions from NMR data alone is difficult. This paper describes an approach for identifying the expected atomic positions on clay minerals by combining machine learning (ML) with experimentally observed chemical shifts. A linear ridge regression model for ML is constructed from the smooth overlap of atomic position descriptor and gauge-including projector augmented wave (GIPAW) ab initio data. The constructed ML model predicts the GIPAW data to within a 3 ppm root-mean-squared error. At this stage, the 133Cs chemical shifts can be instantaneously calculated from the Cs positions on any clay layers using ML. The inverse analysis, which derives the atomic positions from experimentally observed chemical shifts, is developed from the ML model. The input data for the inverse analysis are the layer structure and the experimentally observed chemical shifts. The Cs positions for the targeted chemical shifts are then output. Inverse analysis is applied to montmorillonite, and the resultant Cs positions are found to be consistent with previous results (Ohkubo, T.; et al. J. Phys. Chem. A 2018, 122, 9326-9337). The Cs positions on saponite clay are also clarified from experimentally observed chemical shifts and inverse analysis.
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Affiliation(s)
- Takahiro Ohkubo
- Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho Inage-ku, Chiba 263-8522, Japan
| | - Akihiro Takei
- Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho Inage-ku, Chiba 263-8522, Japan
| | - Yukio Tachi
- Japan Atomic Energy Agency, Muramatsu 4-33, Tokai, Ibaraki 319-1194, Japan
| | - Yuta Fukatsu
- Japan Atomic Energy Agency, Muramatsu 4-33, Tokai, Ibaraki 319-1194, Japan
| | - Kenzo Deguchi
- High Field NMR Group, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan
| | - Shinobu Ohki
- High Field NMR Group, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan
| | - Tadashi Shimizu
- High Field NMR Group, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan
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Dubus J, Leonhardt N, Latrille C. Multi-cation exchanges involved in cesium and potassium sorption mechanisms on vermiculite and micaceous structures. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:1579-1594. [PMID: 35918581 DOI: 10.1007/s11356-022-22321-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
Vermiculite and micaceous minerals are relevant Cs+ sorbents in soils and sediments. To understand the bioavailability of Cs+ in soils resulting from multi-cation exchanges, sorption of Cs+ onto clay minerals was performed in batch experiments with solutions containing Ca2+, Mg2+, and K+. A sequence between a vermiculite and various micaceous structures has been carried out by conditioning a vermiculite at various amounts of K. Competing cation exchanges were investigated as function of Cs+ concentration. The contribution of K+ on trace Cs+ desorption is probed by applying different concentrations of K+ on Cs-doped vermiculite and micaceous structures. Cs sorption isotherms at chemical equilibrium were combined with elemental mass balances in solution and structural analyses. Cs+ replaces easily Mg2+ > Ca2+ and competes scarcely with K+. Cs+ is strongly adsorbed on the various matrix, and a K/Cs ratio of about a thousand is required to remobilize Cs+. Cs+ is exchangeable as long as the clay interlayer space remains open to Ca2+. However, an excess of K+, as well as Cs+, in solution leads to the collapse of the interlayer spaces that locks the Cs into the structure. Once K+ and/or Cs+ collapse the interlayer space, the external sorption sites are then particularly involved in Cs sorption. Subsequently, Cs+ preferentially exchanges with Ca2+ rather than Mg2+. Mg2+ is extruded from the interlayer space by Cs+ and K+ adsorption, excluded from short interlayer space and replaced by Ca2+ as Cs+ desorbs.
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Affiliation(s)
- Julien Dubus
- Service d'Etude du Comportement Des Radionucléides, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
- CEA, CNRS, BIAM, Aix Marseille Université, 13108, Saint-Paul-Lez-Durance, France
| | - Nathalie Leonhardt
- CEA, CNRS, BIAM, Aix Marseille Université, 13108, Saint-Paul-Lez-Durance, France
| | - Christelle Latrille
- Service d'Etude du Comportement Des Radionucléides, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France.
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Nazar A, Rakitskaya T, Kios T. Influence of Acid Modification of Natural Phlogopite on Catalytic Activity of Supported Pd(II)-Cu(II) Complexes in the Reaction of Oxidation of Carbon Monoxide by Atmospheric Oxygen. CHEMISTRY JOURNAL OF MOLDOVA 2022. [DOI: 10.19261/cjm.2022.927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The paper presents original results on the of nitric acid concentrations effect on structure, morphology, protolytic properties and the activity of low-temperature carbon monoxide oxidation catalysts based on acid-modified phlogopite (Н-Phl-1) and K2PdCl4, Cu(NO3)2, KBr base components. The obtained samples were characterized by XRD, SEM, FT-IR spectroscopy and pH metric method. The obtained catalyst Pd(II)-Cu(II)/8H-Phl-1 can be recommended for use in respiratory devices.
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