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Thermal and kinetic analysis of uranium salts

Part 1. Uranium (VI) oxalate hydrates

Journal of Thermal Analysis and Calorimetry
Authors: Halil Cetişli, Gülbanu Koyundereli Çılgı, and Ramazan Donat

literature about kinetic analysis of each decomposition stages. This conflict and deficiency have indicated a need for more studies on the thermal decomposition of uranyl oxalate. In this study, thermal decomposition of UO 2 C 2 O 4 ·3H 2 O compound

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isothermal data. One of prerequisites for this kinetic analysis is to get data of conversion rate of high accuracy. Thus if we observe the non-stoichiometry by changing temperature frequency and extract combined data of conversion and rate of conversion

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Abstract  

For complex decomposition reactions, traditional methods, such as TG and DSC cannot fully resolve all of the steps in the reaction. Evolved gas analysis (EGA) offers another tool to provide more information about the decomposition mechanism. The decomposition of sodium bicarbonate was studied by TG, DSC and EGA using a simultaneous thermal analysis unit coupled to a FTIR. The decomposition of sodium bicarbonate involves two reaction products H2O and CO2, which are not evident from either TG or DSC measurements alone. A comparison of the reaction kinetics from TG, DTG and EGA data were compared.

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(activation energy, pre-exponential factor, and conversion function) of each degradation step is one important target of kinetic investigations. Many kinetic analysis methods have been developed, among which isoconversional methods have been widely used [ 1

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Computational thermal and kinetic analysis

Complete standard procedure to evaluate the kinetic triplet form non-isothermal data

Journal of Thermal Analysis and Calorimetry
Authors: A. Rotaru and M. Goşa

Abstract  

Advanced software (TKS-SP2.0 version) for thermal and kinetic analysis, for determining the non-isothermal kinetic parameters of heterogeneous processes has been developed. The dynamic handle of conversion degree steps and ranges, heating rates and kinetic models, makes the evaluation of the kinetic parameters much faster, for TG, TPR and dilatometry experiments. The standard procedure for evaluating the kinetic triplet was implemented; several linear isoconversional methods (from generalized KAS to FWO, Li-Tang and Friedmann methods), IKP method, Perez-Maqueda et al. criterion (both by Differential equation) and Master plots method. The software is designed mainly for data processing of experimental files, but may also import other already transformed numeric data.

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Thermal and kinetic analysis of uranium salts

Part 2. Uranium (VI) acetate hydrates

Journal of Thermal Analysis and Calorimetry
Authors: Gülbanu Koyundereli Çılgı, Halil Cetişli, and Ramazan Donat

, there is a gap in the academic literature about kinetic analysis of each decomposition stage of uranyl acetate salts. However, the kinetic and thermodynamic findings play an important role in solid-state chemistry. This situation has indicated a need for

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Abstract  

In this research, thermogravimetry (TG/DTG) was used to determine the kinetic analysis of different coals and effect of cleaning process on kinetic parameters of raw and cleaned coal samples from Soma, Tuncbilek and Afsin Elbistan regions. Kinetic parameters of the samples were determined using Arrhenius and Coats and Redfern kinetic models and the results are discussed.

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Abstract  

In principle, the kinetic analysis of thermal effects has limitations when based on a single measurement. Using a simulated example and the dehydration of Ca(OH)2 , it will be shown that, through the simultaneous application of non-linear regression to several measurements run at different heating rates (multivariate non-linear regression), the difficult problem of determining the probable reaction type can be reliably solved.

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reactions due to chemical complexity. Many researchers regarded the biomass as consisting of multiple pseudo components to simplify the decomposition kinetic analysis, thereby different apparent kinetic models were suggested to describe the mass loss

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Abstract  

A critical study of the use of isoconversional methods for the kinetic analysis of non-isothermal data corresponding to processes with either a real or an apparent variation of the activation energy, E, with the reacted fraction, α, has been carried out using for the first time simulated curves. It has been shown that the activation energies obtained from model-free methods are independent of the heating rate. However, the activation energy shows a very strong dependence of the range of heating rates used for simulating the curves if the apparent change of E with α is caused by overlapping processes with different individual activation energies. This criterion perhaps could be used for determining if a real dependence between E and α is really occurring.

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