Thermochemical study of natural pollucite

Ogorodova, L. P.; Melchakova, L. V.; Киселева, И. А.; Belitsky, Igor A.

doi:10.1016/s0040-6031(03)00048-0

Cited by 88 publications

(14 citation statements)

References 8 publications

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“…Melting temperatures used in the calculation were taken from the literature: 2023 K for CsAlSiO 4 , 46 2173 K for CsAlSi 2 O 6 , 47 and 1693 K for CsAlSi 5 O 12 . 48 The heat capacity at 298.2 K ( C p,298 ) of CsAlSi 2 O 6 was reported in the literature (173.2 J mol –1 K –1 ) 39,40 and the corresponding values for CsAlSiO 4 and CsAlSi 5 O 12 were estimated to be 121.9 and 299.6 J mol –1 K –1 respectively, from the Neumann–Kopp rule (simple stoichiometric summation of the C p,298 values of Cs 2 O, Al 2 O 3 , SiO 2 ).cWe shifted the estimated standard enthalpy of CsAlSiO 4 (−2121 by Lindemer 41 and −2133 kJ mol −1 by Taylor 42 ) and CsAlSi 5 O 12 by Lindemer 41 (−5805 kJ mol −1 ) to better reproduce the melting temperatures, as well as to obtain the plausible high temperature behaviors of Cs.d C p , Δ f H °, and S ° for gases were estimated using the statistical equations in ref (49) or (50), and the details are presented in the Supporting Information. The thermodynamic properties for elemental Cs, O atom, and O 2 molecule were cited from the NIST database.…”

Section: Calculation Methodsmentioning

confidence: 95%

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

2018

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Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioactive nuclides such as 137 Cs and 134 Cs. To understand the state of radioactive cesium (r-Cs) in the incineration residues of the municipal wastes, research groups studied the concentration and the chemical form of r-Cs in the residues, as well as its water-leaching behavior. In the present study, we conducted thermodynamic equilibrium calculations to estimate the possible chemical forms of r-Cs in the incineration residues. Thermodynamic data for cesium oxides and aluminosilicates were collected and compiled into a new database to perform equilibrium calculations for systems that include Cs. The calculation results suggested that Cs (radiocesium and stable cesium) in municipal solid waste was transformed into gaseous CsCl or crystalline aluminosilicate at incineration temperatures and, when a molten aluminosilicate phase (i.e., slag phase) was generated, a proportion of the Cs species was dissolved into the slag phase. In the case of sewage sludge, Cs was calculated to be transformed mostly into crystalline aluminosilicate at incineration temperatures, whereas by analogy with the behaviors of Na and K, Ca,Cs-phosphate double salts were also potential incineration products. These results could account for the high leaching rates of r-Cs from the MSW incineration fly ash and the low leaching rates from the MSW incineration bottom ash and SS incineration fly ash reported in earlier studies. In the case of dewatered SS that included a large amount of slaked lime as a flocculant, it was exceptionally difficult for the calculation to represent the fate of Cs, and we needed to include the contribution of silica sand in a fluidized-bed combustor in the equilibrium calculation to represent the low leaching rates of alkali species from the dewatered SS fly ash. From the results of the thermodynamic equilibrium calculations and also from the calculated standard Gibbs energy of cesium aluminosilicate formation/decomposition reactions, the effects of waste composition and incineration temperature on the fate of Cs were examined: High incineration temperature and large amounts of Ca and Cl in the waste composition increased the fraction of gaseous CsCl in the furnace and thus resulted in the high distribution ratios of Cs in the fly ash of MSW and the high leaching rates of Cs from the fly ash.

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Section: Calculation Methodsmentioning

confidence: 95%

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

2018

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“…(Kiseleva et al, 2001). в Справочные данные (Robie, Hemingway, 1995 (Ogorodova et al, 2003); е (Киселева и др., 1979); ж (Westrich, Navrotsky, 1981 Для расчета значений энергии Гиббса образования апофиллитов из элементов были оценены отсутствующие в литературе величины их стандартных энтропий (табл. 3).…”

Section: результаты и их обсуждениеunclassified

Thermodynamic properties of fluorapophyllite-(k) and hydroxylapophyllite-(k)

et al. 2019

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Thermochemical study of natural minerals of the apophyllite group: fluorapophyllite-(K) KCa4[Si8O20]F . 8H2O (Maharashtra, India) (I) and hydroxylapophyllite-(K) KCa4[Si8O20]OH . 8H2O (Norilsk, Russia) (II) were performed on a high-temperature heat-flux microcalorimeter Tian–Calvet “Setaram” (France) using the melt solution calorimetry method. The first data on the enthalpies of formation from the elements for the minerals studied are obtained: -13 205±13 kJ/mol (I) and -13 054±20 kJ/mol (II). The values of their standard entropies and Gibbs energies of formation are estimated.

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“…c Calculated using the reference data on [H 0 (973 K)-H 0 (298.15 K)] (Robie and Hemingway 1995) and experimental data on D sol H 0 (973 K) according to Kiseleva et al (1979). d Calculated using the reference data on [H 0 (973 K)-H 0 (298.15 K)] (Robie and Hemingway 1995) and experimental data on D sol H 0 (973 K) according to Ogorodova et al (2003). e Calculated using the reference data on [H 0 (973 K)-H 0 (298.15 K)] (Robie and Hemingway 1995) and experimental data on D sol H 0 (973 K) according to Kiseleva (1976).…”

Section: Calorimetric Measurementsmentioning

confidence: 99%

Natural Mg-Fe clinochlores: Enthalpies of formation and dehydroxylation derived from calorimetric study

Ogorodova

Вигасина

Melchakova

et al. 2016

American Mineralogist

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This paper presents the results of the first experimental thermochemical investigation of two natural trioctahedral chlorites (clinochlores). The study was performed with the help of a high-temperature heat-flux Tian-Calvet microcalorimeter. The samples were characterized by X-ray spectroscopy analysis, X-ray powder diffraction, thermal analysis, and FTIR spectroscopy. The enthalpies of formation of clinochlores were found using the melt solution calorimetry method to be: -8806 ± 16 kJ/mol for composition (Mg 4.9 Fe 2+ 0.3 Al 0.8 )[Si 3.2 Al 0.8 O 10 ](OH) 8 and -8748 ± 24 kJ/mol for composition (Mg 4.2 Fe 2+ 0.6 Al 1.2 ) [Si 2.8 Al 1.2 O 10 ](OH) 8 . The experimental data for natural samples allowed calculating the enthalpies of formation for end-members and intermediate members of the clinochlore (Mg 5 Al)[Si 3 AlO 10 ](OH) 8 and chamosite (Fe 5 Al)[Si 3 AlO 10 ](OH) 8 series. An important feature of the clinochlore structure is the presence of two distinct hydroxyl-containing octahedral layers: the interlayer octahedral sheet and octahedral 2:1 layer; the enthalpies of water removal from these positions in clinochlore structure were determined as: 53 ± 20 kJ/(mol·H 2 O) and 131 ± 10 kJ/(mol·H 2 O), respectively. These obtained first thermodynamic characteristics of Mg-Fe clinochlores can be used for quantitative thermodynamic modeling of geological and industrial processes including clinochlores of different composition.

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Thermochemical study of natural pollucite

Cited by 88 publications

References 8 publications

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation

Thermodynamic properties of fluorapophyllite-(k) and hydroxylapophyllite-(k)

Natural Mg-Fe clinochlores: Enthalpies of formation and dehydroxylation derived from calorimetric study

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