Kinetic study of the thermal dehydration of calcium oxalate monohydrate

“…36 The downward slope exhibited by this curve has also been reported by others who have studied this dehydration. [37][38][39] Masuda et al have attributed this effect to the combination of two separate dehydration mechanisms. 38 They postulate that surface diffusion of water is largely responsible for low temperature mass loss (i.e., lower conversion), whereas at higher temperatures the process primarily involves a phase boundary transition followed by rapid diffusion.…”

Section: Resultsmentioning

confidence: 99%

Isoconversion Effective Activation Energy Profiles by Variable Temperature Diffuse Reflection Infrared Spectroscopy

White

2008

Appl Spectrosc

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Thermal process characterization based on calculating effective activation energies from variable temperature diffuse reflection infrared spectroscopy (VT-DRIFTS) measurements is demonstrated. Experimental factors that affect the accuracies of activation energy values are outlined. Infrared radiation scattering efficiency, thermal conductivity, and inertness towards chemical reactions are factors that should be considered when selecting an appropriate diluent for preparing samples. The Kubelka-Munk representation is superior to apparent absorbance when baseline variations in spectra measured at different temperatures can be minimized. Variable-temperature infrared spectral features, such as integrated absorption band area, can be used to compute isoconversion effective activation energies, provided that measured quantities are proportional to species concentrations.

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“…About 1000 data points were collected at a given time interval for each dehydration process. From these data, the fraction of dehydration (t~) was calculated [7][8][9][10][11][12].…”

Section: Methodsmentioning

confidence: 99%

The effect of water vapour pressure on the thermal dehydration of yttrium formate dihydrate

Masuda

Ito

1992

Journal of Thermal Analysis

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The kinetics of the thermal dehydration of yttrium formate dihydrate was studied by means of isothermal gravimetry under various water vapour pressures from 5• to 8 tort. On the whole, the dehydration was described as the three dimensional phase boundary reaction, R3. An unusual dependence of the rate of dehydration on the atmospheric water vapour pressure was observed: with increasing water vapour pressure, the rate increased at first, passed through a maximum, and then decreased gradually to a constant value. These phenomena were similar to the Smith-Topley effect. The mechanism of the phenomena can be described on the basis of the crystallinity of the dehydrated product phase.

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Kinetic study of the thermal dehydration of calcium oxalate monohydrate

Cited by 34 publications

References 12 publications

A unified approach to kinetic processing of nonisothermal data

A unified approach to kinetic processing of nonisothermal data

Isoconversion Effective Activation Energy Profiles by Variable Temperature Diffuse Reflection Infrared Spectroscopy

The effect of water vapour pressure on the thermal dehydration of yttrium formate dihydrate

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