Thermal decomposition of enalapril maleate studied by dynamic isoconversional method

2005 ◽  
Vol 79 (2) ◽  
pp. 259-262 ◽  
Author(s):  
E. A. Gómez Pineda ◽  
A. D. Martins Ferrarezi ◽  
J. G. Ferrarezi ◽  
A. A. Winkler Hechenleitner
Keyword(s):  
Thermal Decomposition ◽  
Isoconversional Method ◽  
Enalapril Maleate

scholarly journals Kinetic Analysis of the Thermal Decomposition of Polymer-Bonded Explosive Based on PETN: Model-Fitting Method and Isoconversional Method

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Trung Toan Nguyen ◽  
Duc Nhan Phan ◽  
Van Thom Do ◽  
Hoang Nam Nguyen
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Model Fitting ◽  
Isoconversional Method ◽  
Isothermal Tg ◽  
Decomposition Reactions ◽  
Model Free ◽  
Negative Effect ◽  
Adverse Influence ◽  
Vacuum Stability Test

This work investigates kinetics and thermal decomposition behaviors of pentaerythritol tetranitrate (PETN) and two polymer-bonded explosive (PBX) samples created from PETN (named as PBX-PN-85 and PBX-PP-85) using the vacuum stability test (VST) and thermogravimetry (TG/DTG) techniques. Both model-free (isoconversional) and model-fitting methods were applied to determine the kinetic parameters of the thermal decomposition. It was found that kinetic parameters obtained by the modified Kissinger–Akahira–Sunose method (using non-isothermal TG/DTG data) were close to those obtained by the isoconversional and model-fitting methods that use isothermal VST data. The activation energy values of thermal decomposition reactions were 125.6–137.1, 137.3–144.9, and 143.9–152.4 kJ·mol−1 for PBX-PN-85, PETN, and PBX-PP-85, respectively. The results demonstrate the negative effect of the nitrocellulose-based binder in reducing the thermal stability of single PETN, while the polystyrene-based binder seemingly shows no adverse influence on the thermal decomposition of PETN in our presented PBX compositions.

scholarly journals Thermal Decomposition of Brominated Butyl Rubber

2021 ◽  
Author(s):  
Wei Zhang ◽  
Jinping Xiong ◽  
Yang Zang ◽  
Yanli Lu ◽  
Weisheng Lin ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Isoconversional Method ◽  
Butyl Rubber ◽  
Heating Rates ◽  
Excellent Thermal Stability ◽  
Small Peak ◽  
Air Atmosphere ◽  
Brominated Butyl Rubber ◽  
Derivative Thermogravimetry

The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31–228.13 kJ·mol-1 at various heating rates. The non-isothermal degradation was found to be a first order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggested that brominated butyl rubber had excellent thermal stability. This study will indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.

scholarly journals Thermal decomposition and their kinetics of mercury(ii) perchlorate complex with 4-aminopyridine and water

2019 ◽  
Vol 8 (3) ◽  
pp. 649-653
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Rapid Heating ◽  
Model Fitting ◽  
Isoconversional Method ◽  
Molecular Formula ◽  
Isothermal Tg ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Perchlorate Complex

Copper perchlorate complex with 4-aminopyridine and water has been prepared with molecular formula [Hg2(C5H6N2)3(ClO4)4].2H2O. It has been characterised by elemental analysis, thermogravimetry, and IR spectroscopic data. Thermal behaviours have been studied by thermogravimetry (TG) in static air and simultaneous thermogravimetry-derivative thermogravimetry analysis (TG-DTG) in flowing nitrogen atmosphere. Complex decomposes in four steps (less resolved). Difference in decomposition under air and inert atmosphere has been also discussed. Kinetics of thermal decomposition has been investigated using isothermal TG data recorded at five different temperatures applying model-fitting as well as isoconversional method on these data. Model-fitting methods have yielded a single value of activation energy whereas isoconversional method has given different values of activation energy for each extent of conversion, α. Response of synthesized complex towards rapid heating has been investigated by recording explosion delay time (DE) at five different temperatures and using these data kinetics of explosion has been analysed. Activation energy for explosion has been also calculated.

scholarly journals Thermal Decomposition of Maya Blue: Extraction of Indigo Thermal Decomposition Steps from a Multistep Heterogeneous Reaction Using a Kinetic Deconvolution Analysis

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2515 ◽  
Author(s):  
Yamamoto ◽  
Koga
Keyword(s):  
Thermal Decomposition ◽  
Clay Minerals ◽  
Materials Science ◽  
Heterogeneous Reaction ◽  
Practical Method ◽  
Isoconversional Method ◽  
Deconvolution Analysis ◽  
Decomposition Processes ◽  
Maya Blue ◽  
Kinetic Deconvolution

Examining the kinetics of solids’ thermal decomposition with multiple overlapping steps is of growing interest in many fields, including materials science and engineering. Despite the difficulty of describing the kinetics for complex reaction processes constrained by physico-geometrical features, the kinetic deconvolution analysis (KDA) based on a cumulative kinetic equation is one practical method of obtaining the fundamental information needed to interpret detailed kinetic features. This article reports the application of KDA to thermal decomposition of clay minerals and indigo–clay mineral hybrid compounds, known as Maya blue, from ancient Mayan civilization. Maya blue samples were prepared by heating solid mixtures of indigo and clay minerals (palygorskite and sepiolite), followed by purification. The multistep thermal decomposition processes of the clay minerals and Maya blue samples were analyzed kinetically in a stepwise manner through preliminary kinetic analyses based on a conventional isoconversional method and mathematical peak deconvolution to finally attain the KDA. By comparing the results of KDA for the thermal decomposition processes of the clay minerals and the Maya blue samples, information about the thermal decomposition steps of the indigo incorporated into the Maya blue samples was extracted. The thermal stability of Maya blue samples was interpreted through the kinetic characterization of the extracted indigo decomposition steps.

scholarly journals Recovery of ammonia from wastewater through chemical precipitation

2019 ◽  
Vol 142 (3) ◽  
pp. 1303-1314 ◽  
Author(s):  
Lavinia Bianchi ◽  
Kerry Kirwan ◽  
Luca Alibardi ◽  
Marc Pidou ◽  
Stuart R. Coles
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Study ◽  
Model Fitting ◽  
Ammonium Phosphate ◽  
Chemical Precipitation ◽  
Isoconversional Method ◽  
Added Value ◽  
Magnesium Ammonium Phosphate ◽  
Mechanism Of Decomposition ◽  
Magnesium Ammonium

AbstractChemical precipitation is a consolidated technique applied in wastewater treatment to remove and recover phosphorous and ammonium that remain in the effluent after the anaerobic digestion treatment. The precipitate is magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O), also known as struvite, and it is sold as a slow-release fertiliser. However, the value of struvite is quite low and has a limited market. Furthermore, it precipitates with heavy metals and other impurities that need to be removed to make the fertiliser commercially viable. This study looked at the thermal decomposition of struvite to recover added value products and recycle the magnesium for further precipitation. A kinetic study was carried out to understand the mechanism of decomposition and the formation of the different solid phases, which is fundamental for the design and optimisation of the technology. The thermogravimetric study confirmed that thermal decomposition is possible, but ammonia could not be completely released below 250 °C. The thermal analysis also led to the determination of the energy required for the decomposition, found to be 1.87 kJ g−1, which also includes the evaporation of water and ammonia. The kinetic study through the isoconversional method showed the presence of two major reactions, and the model-fitting approach identified the diffusion model as the best fit for the first reaction. The activation energy of the first reaction found with this method was 0.24 kJ g−1, comparable with the data obtained from the isoconversional method. The two-stage decomposition reactions were proposed, and the final calcination product was confirmed as magnesium pyrophosphate, which could be used in agriculture or dissolved in diluted mineral acids solution to separate the phosphate from the magnesium.

Determined the Activation Energy of the Decomposition of Calcium Carbonate by Nonlinear Isoconversional Method

2014 ◽  
Vol 881-883 ◽  
pp. 1522-1525
Author(s):  
Song Zhang ◽  
Dan Tang
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Calcium Carbonate ◽  
Isoconversional Method ◽  
Solid Reaction ◽  
Nonisothermal Conditions

The nonlinear isoconversional method has been applied to data for nonisothermal thermal decomposition of calcium carbonate. It is shown that the dependence derived from nonisothermal data can reveal the complexity of solid reaction. Therefore, the nonlinear isoconversional method is recommended as a trustworthy way of obtaining the activation energy of solid reaction under nonisothermal conditions.

scholarly journals Study of the thermal behavior in solid state of Mn(II)-Diclofenac Complex

2018 ◽  
Vol 43 (1) ◽  
pp. 59 ◽  
Author(s):  
Marcelo Kobelnik ◽  
Valdecir Ângelo Quarcioni ◽  
Adélia Emília De Almeida ◽  
Clóvis Augusto Ribeiro ◽  
Marisa Spirandeli Crespi
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Solid State ◽  
Thermal Behavior ◽  
Isoconversional Method ◽  
Exothermic Peak ◽  
X Ray ◽  
Purge Gas ◽  
Dsc Curves

The preparation, characterization and thermal behavior of Mn(II)-diclofenac solid-state complex was investigated by simultaneous TG/DTA and DTG curves, DSC, X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques. The thermal evaluation was carried out with sample masses of 2 and 5 mg, with the purpose of comparing the values of activation energy regarding dehydration, monotropic phase transition and thermal decomposition in both samples mass. The DSC curves were obtained in opened and with crimped lids crucibles of aluminum under oxygen purge gas and static air (without purge gas). The DTA and DSC curves show an exothermic peak between 150-180 °C depending on heating rate, which can be attributed to the monotropic non-reversible reaction. The activation energy (Ea/kJ mol-1) to dehydration, the monotropic phase transition and the first thermal decomposition step were determined by Capela-Ribeiro nonlinear isoconversional method. The activation energy under oxygen dynamic purge gas shows lower values compared to those obtained under static air.

scholarly journals Thermal Decomposition of Brominated Butyl Rubber

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6767
Author(s):  
Wei Zhang ◽  
Yang Zang ◽  
Yanli Lu ◽  
Weisheng Lin ◽  
Shengyun Zhao ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Isoconversional Method ◽  
Butyl Rubber ◽  
Heating Rates ◽  
Excellent Thermal Stability ◽  
Small Peak ◽  
Air Atmosphere ◽  
Brominated Butyl Rubber ◽  
Derivative Thermogravimetry

The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates, while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31 to 228.13 kJ·mol−1 at various heating rates. The non-isothermal degradation was found to be a first-order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggest that brominated butyl rubber has excellent thermal stability. This study can indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

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