Application of simplified version of advanced isoconversional procedure in non-isothermal kinetic study
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The single phase NH4Co0.9Zn0.1PO4·H2O was prepared via solid-state reaction at 80 °C. Based on a simplified version of advanced isoconversional procedure, the values of activation energy E α associated with the first, second, and third stages of the thermal decomposition of NH4Co0.9Zn0.1PO4·H2O were obtained, which demonstrates that the third stage is a kinetically complex process, and the first and second stages are single-step kinetic processes and can be described by a unique kinetic triplet [E α, A, and g(α)]. The most probable reaction mechanisms of the first two stages were estimated by the comparison between experimental plots and modeled results. The values of pre-exponential factor A of the two stages were obtained on the basis of E α and the reaction mechanisms. The distributed activation energy model was applied to study the third stage. Besides, some thermodynamic functions of transition state complexes (ΔS ≠, ΔH ≠, and ΔG ≠) of the two stages were also calculated.
KeywordsNH4Co0.9Zn0.1PO4·H2O Non-isothermal kinetics Thermodynamics Thermal decomposition Thermogravimetric analysis Solid-state reaction
This study was financially supported by the Key laboratory of new processing technology for nonferrous metals and materials, Ministry of Education, Guangxi University (No. GXKFZ-02); the Guangxi Natural Scientific Foundation of China (Grant Nos. 2012GXNSFAA053019 and 0991108); and the Guangxi Science and Technology Agency Research Item of China (Grant No. 0895002–9).
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