Investigation on the drying and decomposition of sodium oxalate

Yoshimori, Takayoshi; Asano, Yoshihiro; Toriumi, Yasuo; Shiota, T.

doi:10.1016/0039-9140(78)80158-1

Cited by 12 publications

(11 citation statements)

References 9 publications

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“…Present results of the thermodynamic properties of this important reaction of thermal decomposition complement the previous kinetic studies performed by several authors [92][93][94]. The decomposition temperature of sodium oxalate was placed at about 290ºC (563 K) in previous experimental studies [94]. As it may be appreciated in Figure 8, the calculated free energy of reaction becomes negative at a temperature of 84ºC (357.3 K) and, therefore, the sodium oxalate crystalline material (natroxalate) appears to start to decompose already at lower temperatures.…”

Section: Thermal Decomposition Of Natroxalatesupporting

confidence: 85%

“…The results are also displayed in Figure 8. Present results of the thermodynamic properties of this important reaction of thermal decomposition complement the previous kinetic studies performed by several authors [92][93][94]. The decomposition temperature of sodium oxalate was placed at about 290ºC (563 K) in previous experimental studies [94].…”

Section: Thermal Decomposition Of Natroxalatesupporting

confidence: 80%

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Study of the structural, vibrational and thermodynamic properties of natroxalate mineral using density functional theory

Colmenero

Timón

2018

Journal of Solid State Chemistry

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Natroxalate mineral, Na2C2O4, is a fundamental oxalate mineral widespread in nature, present in humans, animals and plants, as well as in naturally occurring minerals. The characterization of oxalate minerals is extraordinarily important since these organic minerals are indicators of environmental events and of the presence of biological activity, because they are commonly of biological origin. These minerals are currently under study to investigate the possible biological activity on Mars. The identification of these compounds is usually performed by X-ray diffraction and Raman spectroscopy. Theoretical calculations are of great value for the study and interpretation of the results of these experimental techniques. In this work, natroxalate mineral structure and Raman spectrum was studied by first principle calculations based on the density functional theory. The computed structure of natroxalate reproduces the one determined experimentally by X-ray diffraction (monoclinic symmetry, space group P21/c; lattice parameters a=3.449 Å, b=5.243 Å; c=10.375 Å). Lattice parameters, bond lengths, bond angles and X-ray powder pattern were found to be in very good agreement with their experimental counterparts. Raman spectrum was then computed by means of density functional perturbation theory and compared with the experimental spectrum. Since the results were also found in agreement with the experimental data, a normal mode analysis of the theoretical spectra was carried out and used in order to assign the main bands of the Raman spectrum. The band found at about 567 cm -1 , described as a single peak in previous experimental works, is shown clearly to have two contributing bands. Finally, two bands of the observed spectrum, located at the wavenumbers 1750 and 1358 cm -1 , were not found in the theoretical spectrum. This is because these bands correspond to an overtone, 2ν1 (ν1=875 cm -1 ), and a combination band, ν1+ν2 (ν1,ν2 =875, 481 cm -1 ), respectively. Finally, the fundamental thermodynamic properties of natroxalate mineral were determined. The calculated specific heat at 298.15 K is in excellent agreement with the experimental value, the difference being less than 1%. Since for most of these properties there are not experimental values to compare with, their values were predicted.

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Section: Thermal Decomposition Of Natroxalatesupporting

confidence: 85%

Section: Thermal Decomposition Of Natroxalatesupporting

confidence: 80%

Study of the structural, vibrational and thermodynamic properties of natroxalate mineral using density functional theory

Colmenero

Timón

2018

Journal of Solid State Chemistry

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“…Since the results of calculations of electronic structure and topological properties of electron density and BVM analysis carried out for anhydrous sodium oxalate are very similar to these obtained for lithium oxalate, one can Table 4 The results of BVM analysis carried out for anhydrous sodium oxalate: bond and atomic valences s ij and V ij , atomic residual strain factors d i and global structure instability index D expect to find analogous to the described above series of consecutive steps of bonds breaking/forming during thermal decomposition process and decomposition of anhydrous sodium oxalate to sodium carbonate [28,29] (since both oxalate and carbonate structures are very similarsuch structural alteration can go very easily [30] (Fig. 2).…”

Section: Anhydrous Lithium Oxalatesupporting

confidence: 70%

Theoretical studies of electronic structure and structural properties of anhydrous alkali metal oxalates

Koleżyński

Małecki

2013

J Therm Anal Calorim

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The theoretical analysis of electronic structure and bonding properties of anhydrous alkali metal oxalates, based on the results of DFT FP-LAPW calculations, Bader's QTAIM topological properties of electron density, Cioslowski and Mixon's topological bond orders [reported in the first part of this paper by Kole_ zyński (doi: 10.1007/s10973-013-3126-z)] and Brown's Bond Valence Model calculations, carried out in the light of thermal decomposition pathway characteristic for these compounds are presented. The obtained results shed some additional light on the origins of the complex pathway observed during thermal decomposition process (two stage process, first the formation of respective carbonate and then decomposition to metal oxide and carbon dioxide). For all structures analyzed, strong similarities in electronic structure and bonding properties were found (ionic-covalent bonds in oxalate anion with C-C bond as the weakest one in entire structure and almost purely ionic between oxalate group and alkali metal cations), allowing us to propose the most probable pathway consisting of consecutive steps, leading to carbonate anion formation with simultaneous cationic sublattice relaxations, which results in relative ease of respective metal carbonate formation.

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“…Zones 2-4 were assigned to multiple processes, overlapping with one another but resulting in a total mass loss that corresponds extremely well to the refined oxalate occupancy of about 0.45 per [AlSiO 4 ] 6 unit, a loss of approximately 4.7% of the starting sample mass. As has been shown by FT-IR, heating of the sample leads to the oxalate originally within the structure oxidizing to form sodium carbonate species and carbon monoxide [14,15]. As temperatures are further elevated, this carbonate is released from the framework as CO 2 [3,7,9] and eventually leads to the collapse of the cancrinite framework as observed in zones 4 and 5.…”

Section: Resultsmentioning

confidence: 89%