Kinetic study of the dehydration of lithium sulphate monohydrate

Valdivieso, Françoise; Bouineau, Vincent; Pijolat, Michèle; Soustelle, Michel

doi:10.1016/s0167-2738(97)00238-5

Cited by 23 publications

(27 citation statements)

References 2 publications

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“…In these models, it is possible to distinguish two alternatives for the growth process : either the growth is isotropic, as for example in the Mampel's model [15], or it is anisotropic as for example in the Valdivieso et al's [12] or Jacobs and Tompkins's [16,17] models. In our experiments, the kinetic rate corresponds to the dehydration of a unique crystal, which means that only the first case (isotropic) is expected, since the second one should only be encountered with powders.…”

Section: Figure 2: Kinetic Curves Obtained For the Dehydration Of Thrmentioning

confidence: 99%

“…With the Monte-Carlo simulations, it thus will be possible to show if some fluctuations of the nucleation frequency γ exist over a large number of single crystals transformed in the same experimental conditions : this would explain the behaviour of Li 2 SO 4 ·H 2 O powder in which the nucleation occurs successively at different times on the grains (cf "nucleation and anisotropic growth" model described in [12]). Monte Carlo simulations offer also the possibility to investigate the variations of γ with the temperature and the water vapour pressure and thus to better understand the mechanism of nucleation which is still not well described.…”

Section: Figure 7: Comparison Between Experimental and Calculated Kinmentioning

confidence: 99%

“…The kinetics of this reaction have been extensively studied [1][2][3][4][5][6][7][8][9][10][11][12][13]. These works have shown that the isothermal kinetic curves obtained for powders, i.e.…”

Section: A-introduction a A --I I N N T T R R O O D D U U C C T T I Imentioning

confidence: 99%

“…Valdivieso et al [12] have studied the dehydration of commercial Li 2 SO 4 ,H 2 O powder by means of isothermal thermogravimetry under various water vapour pressures. They proposed a nucleation and anisotropic growth model in order to account for the sigmoid shape of the kinetic curves α(t): the nucleation occurs at the surface of the solid and is followed by a rapid two-dimensional growth (the particles are covered by a thin layer of product as soon as they are nucleated but nuclei do not appear at the same time on all the grains), then the growth proceeds towards the centre of the grains, the rate-limiting step being located at the internal interface.…”

Section: A-introduction a A --I I N N T T R R O O D D U U C C T T I Imentioning

confidence: 99%

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Experimental study and Monte-Carlo simulation of the nucleation and growth processes during the dehydration of Li2SO4·H2O single crystals

Favergeon

Pijolat

Valdivieso

et al. 2005

Phys. Chem. Chem. Phys.

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A kinetic model for the dehydration of lithium sulfate monohydrate is proposed in order to account for experimental data obtained on single crystals by thermogravimetry at 80 1C under fixed water vapour pressure, and by optical microscopy. This model is based on the assumptions of Mampel's model, the nucleation takes place randomly at the surface of the solid and is followed by isotropic growth toward the centre of the crystal. Calculated rates da/dt are obtained by means of Monte-Carlo simulations and compared to the experimental ones, which leads to the determination of two kinetic constants: the areic frequency of nucleation (in number of nuclei m À2 s À1 ) and the areic reactivity of growth (in mol m À2 s À1 ).

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Section: Figure 2: Kinetic Curves Obtained For the Dehydration Of Thrmentioning

confidence: 99%

Section: Figure 7: Comparison Between Experimental and Calculated Kinmentioning

confidence: 99%

Section: A-introduction a A --I I N N T T R R O O D D U U C C T T I Imentioning

confidence: 99%

Section: A-introduction a A --I I N N T T R R O O D D U U C C T T I Imentioning

confidence: 99%

See 2 more Smart Citations

Experimental study and Monte-Carlo simulation of the nucleation and growth processes during the dehydration of Li2SO4·H2O single crystals

Favergeon

Pijolat

Valdivieso

et al. 2005

Phys. Chem. Chem. Phys.

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“…1) is chosen as a representative reaction for comparative investigations. This single-step reaction is relatively simple and has extensively been studied for both powders [1][2][3][4][5] and single crystals [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], which makes it suitable for comparison. …”

Section: Introductionmentioning

confidence: 99%

An experimentally validated numerical model of interface advance of the lithium sulfate monohydrate dehydration reaction

Lan

Steenhoven

Rindt

2016

J Therm Anal Calorim

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Interface advance plays an essential role in understanding the kinetics and mechanisms of thermal decomposition reactions such as the dehydration reaction of lithium sulfate monocrystals. However, many fundamental processes including mass transfer during interface advance are still not clear. In this work, the dynamics of interface advance, involving interaction between interfacial reaction and mass diffusion, is investigated numerically together with microscopy observations. A mathematical model is developed for interface advance with a moving boundary and then solved by using a conservative scheme. To examine the significance between the intrinsic chemical reaction and mass diffusion, a Damköhler number is defined as Da ¼ k r L=ðD e c 0 Þ. Numerical results at various Da values are discussed to distinguish the limiting step of the dehydration reaction of lithium sulfate monocrystals. Moreover, experiments are carried out with a hot-stage microscopy system where the propagation of the reaction interface into the crystal bulk is followed in situ. By fitting the experimental results with the numerical results, the effective diffusivity of water through the dehydrated crystal is estimated to be in the order of 10 À8 m 2 s À1 . According to the corresponding Da values, it is found that, within the reaction temperature ranging from 110 to 130°C and a partial water vapor pressure of 13 mbar, the rate of dehydration interface advance in the bulk of large crystals (typically in the order of millimeters) is not constant, but shows a small decrease over time due to the influence of mass diffusion.

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A mechanism of nucleation during thermal decomposition of solids

2008

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International audienceA microscopic model based on the appearance, diffusion, and aggregation of point defects allows to calculate the time of appearance of the first nucleus on a surface during a reaction between a solid and a gas. Calculated distributions of these times of appearance of the first nucleus are qualitatively compared to experimental ones, previously determined. The appearance of the point defects seems to be the most influential step on the time of appearance of the first nucleus. Moreover the comparison between experimental and calculated distributions allows to conclude that the frequency of appearance of the defects is higher on the edges than on the faces of the single crystal

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Kinetic study of the dehydration of lithium sulphate monohydrate

Cited by 23 publications

References 2 publications

Experimental study and Monte-Carlo simulation of the nucleation and growth processes during the dehydration of Li2SO4·H2O single crystals

Experimental study and Monte-Carlo simulation of the nucleation and growth processes during the dehydration of Li2SO4·H2O single crystals

An experimentally validated numerical model of interface advance of the lithium sulfate monohydrate dehydration reaction

A mechanism of nucleation during thermal decomposition of solids

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