Yu. D. Gritsenko, M. F. Vigasina, L. V. Mel’chakova, L. P. Ogorodova, D. A. Ksenofontov, S. K. Dedushenko
{"title":"Thermal and Thermochemical Study of Thaumasite","authors":"Yu. D. Gritsenko, M. F. Vigasina, L. V. Mel’chakova, L. P. Ogorodova, D. A. Ksenofontov, S. K. Dedushenko","doi":"10.1134/S0016702923110046","DOIUrl":null,"url":null,"abstract":"<p>A sample of natural thaumasite Ca<sub>3.0</sub>Si(OH)<sub>6</sub>(CO<sub>3</sub>)<sub>0.9</sub>(SO<sub>4</sub>)<sub>1.1</sub>·12.3H<sub>2</sub>O (N’Chwaning mine, Kalahari manganese ore field, South Africa) was studied by powder X-ray diffraction, infrared absorption and Raman spectroscopy, thermal analysis, and microcalorimetry. The process of thermal transformation of thaumasite was studied using the results of FTIR and Raman spectroscopy. The enthalpy of formation from elements Δ<sub>f</sub><i>H</i><sup>0</sup>(298.15 K) = −8816 ± 30 kJ/mol was determined by high-temperature melt solution calorimetry. The value of the absolute entropy was estimated, and the enthalpy and Gibbs energy of formation of thaumasite of theoretical composition were calculated: 945.4 ± 1.8 J/(mol K), −8699 ± 30 kJ/mol, −7577 ± 30 kJ/mol, respectively.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"61 12","pages":"1273 - 1282"},"PeriodicalIF":0.7000,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochemistry International","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1134/S0016702923110046","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
A sample of natural thaumasite Ca3.0Si(OH)6(CO3)0.9(SO4)1.1·12.3H2O (N’Chwaning mine, Kalahari manganese ore field, South Africa) was studied by powder X-ray diffraction, infrared absorption and Raman spectroscopy, thermal analysis, and microcalorimetry. The process of thermal transformation of thaumasite was studied using the results of FTIR and Raman spectroscopy. The enthalpy of formation from elements ΔfH0(298.15 K) = −8816 ± 30 kJ/mol was determined by high-temperature melt solution calorimetry. The value of the absolute entropy was estimated, and the enthalpy and Gibbs energy of formation of thaumasite of theoretical composition were calculated: 945.4 ± 1.8 J/(mol K), −8699 ± 30 kJ/mol, −7577 ± 30 kJ/mol, respectively.
期刊介绍：
Geochemistry International is a peer reviewed journal that publishes articles on cosmochemistry; geochemistry of magmatic, metamorphic, hydrothermal, and sedimentary processes; isotope geochemistry; organic geochemistry; applied geochemistry; and chemistry of the environment. Geochemistry International provides readers with a unique opportunity to refine their understanding of the geology of the vast territory of the Eurasian continent. The journal welcomes manuscripts from all countries in the English or Russian language.
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