Isothermal kinetic analysis of the thermal decomposition of kaolinite: The thermogravimetric study
TL;DR: In this paper, the authors investigated the de-hydroxylation of medium ordered kaolinite under isothermal conditions by the thermogravimetric analysis (TGA).
About: This article is published in Thermochimica Acta.The article was published on 2010-03-30. It has received 107 citations till now. The article focuses on the topics: Thermogravimetric analysis & Thermal decomposition.
Citations
More filters
TL;DR: In this paper, the authors summarized the most recent achievements in the thermal behavior study of kaolinite intercalation complexes obtained with the most common reagents including potassium acetate, formamide, dimethyl sulfoxide, hydrazine and urea.
162 citations
Journal Article•
TL;DR: In this paper, the authors summarized the most recent achievements in the thermal behavior study of kaolinite intercalation complexes obtained with the most common reagents including potassium acetate, formamide, dimethyl sulfoxide, hydrazine and urea.
Abstract: The kaolinite intercalation and its application in polymer-based functional composites have attracted great interest, both in industry and in academia fields, since they frequently exhibit remarkable improvements in materials properties compared with the virgin polymer or conventional micro and macro-composites. Also of significant interest regarding the kaolinite intercalation complex is its thermal behavior and decomposition. This is because heating treatment of intercalated kaolinite is necessary for its further application, especially in the field of plastic and rubber industry. Although intercalation of kaolinite is an old and ongoing research topic, there is a limited knowledge available on kaolinite intercalation with different reagents, the mechanism of intercalation complex formation as well as on thermal behavior and phase transition. This review attempts to summarize the most recent achievements in the thermal behavior study of kaolinite intercalation complexes obtained with the most common reagents including potassium acetate, formamide, dimethyl sulfoxide, hydrazine and urea. At the end of this paper, the further work on kaolinite intercalation complex was also proposed.
161 citations
TL;DR: In this article, the thermally induced transformation of metakaolin is simulated using molecular dynamics through a step-wise dehydroxylation approach, which is characterized by a loss of crystallinity and a concomitant change in aluminium coordination from octahedral to tetrahedral.
Abstract: The thermally induced transformation of kaolinite to metakaolin is simulated using molecular dynamics through a step-wise dehydroxylation approach. The simulation shows that the removal of structural water through dehydroxylation produces a distortion or buckling effect in the 1 : 1 Al–Si layers, which is due to the migration of the aluminium into vacant sites provided by the inter-layer spacing. The structural change is characterized by a loss of crystallinity and a concomitant change in aluminium coordination from octahedral to tetrahedral, with this study confirming the presence of 5-fold aluminium within the metakaolin structure. The degree and probability of Al migration are proportional to the amount of local disorder within the structure, which is governed by the degree of local hydroxyl group loss. This results in the formation of aluminium clusters within the layers. This study proposes that instead of a uniform structure, metakaolin exhibits regions of differing aluminium concentrations, which can have major effects in the reaction chemistry at those sites.
160 citations
TL;DR: In this article, the thermal decomposition of kaolinite was studied by differential thermogravimetry (DTG) technique under non-isothermal conditions, and the apparent activation energy and frequency factor for the dehydroxylation of kaolin was evaluated by Kissinger method.
120 citations
TL;DR: In this paper, the authors used the Avrami method on the basis of sample mass loss and changes in the intensities of X-ray powder diffraction and FTIR-ATR peaks under isothermal conditions.
98 citations
References
More filters
TL;DR: In this article, the kinetics of thermal dehydration and decomposition CaC 2 O 4 ·H 2 O were studied using thermogravimetry at four rates of linear increase of temperature and two different sample mass.
270 citations
TL;DR: The phase transformation and growth of mullite (3Al 2 O 3 ·2SiO 2 ) in kaolin ceramics have been investigated using X-ray diffractometer, transmission electron microscope, select area electron diffractometers, energy dispersion spectrometer and differential thermal analysis as mentioned in this paper.
Abstract: The phase transformation and growth of mullite (3Al 2 O 3 ·2SiO 2 ) in kaolin ceramics have been investigated using X-ray diffractometer, transmission electron microscope, select area electron diffractometer, energy dispersion spectrometer and differential thermal analysis. The mullite which was transformed from kaolin appears at 1050 °C by XRD and tallies with DTA. The initial mullite crystal showed a plate-like morphology. The Al 2 O 3 content in mullite crystal increased from 49.57 to 71.37 wt.% but the lattice parameters of a , b and c axes decreased from 8.085, 8.106 and 3.215 A to 7.882, 7.974 and 2.946 A, respectively, with the grain width increasing from 20 to 70 nm when the kaolin was sintered at 1300 °C for 30 min. The nonisothermal activation energy of mullite crystallization in kaolin ceramics was 1182.3 kJ mol −1 . The growth morphology parameters n and m were both about 2.0, indicating that the bulk nucleation was dominant in mullitization and the crystal growth was controlled by diffusion. Seemingly, this study has been attempted to provide an integrative presentation of the thermal–structural characterization together with detailed kinetic and mechanistic interpretations.
263 citations
"Isothermal kinetic analysis of the ..." refers background in this paper
...The whole process can be mostly described by reactions [1–4]:...
[...]
...[2] Y....
[...]
TL;DR: In this article, the thermal behavior of a Bio kaolin raw material (Bio) containing mainly well-crystallised kaolinite and muscovite minerals was studied in relation to heating rate, from 3 to 20°C min −1.
194 citations
"Isothermal kinetic analysis of the ..." refers background in this paper
...[1] O....
[...]
...The whole process can be mostly described by reactions [1–4]:...
[...]
...degree of disorder of the kaolinte structure [4], pressure and partial water vapour pressure [5,6], eating rate [1,6], mechanical treatments and ultrasound processng of sample [7,8]....
[...]
TL;DR: In this paper, a quasi-exact analytical solution of Avrami's model when the transformation takes place under continuous heating was obtained with different activation energies for both nucleation and growth rates.
157 citations
Posted Content•
TL;DR: In this paper, a quasi-exact analytical solution of Avrami's model when the transformation takes place under continuous heating was obtained with different activation energies for both nucleation and growth rates, which is also a solution of the so-called Kolmogorov-Johnson-Mehl-Avrami transformation rate equation.
Abstract: Avrami's model describes the kinetics of phase transformation under the assumption of spatially random nucleation. In this paper we provide a quasi-exact analytical solution of Avrami's model when the transformation takes place under continuous heating. This solution has been obtained with different activation energies for both nucleation and growth rates. The relation obtained is also a solution of the so-called Kolmogorov-Johnson-Mehl-Avrami transformation rate equation. The corresponding non-isothermal Kolmogorov-Johnson-Mehl-Avrami transformation rate equation only differs from the one obtained under isothermal conditions by a constant parameter, which only depends on the ratio between nucleation and growth rate activation energies. Consequently, a minor correction allows us to extend the Kolmogorov-Johnson-Mehl-Avrami transformation rate equation to continuous heating conditions.
136 citations