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1.
Thermal behavior of various synthesized transition metal surfactant complexes of the type [M(CH3COO)4]2−[C12H25NH3
+]2 where M: Cu(II), Ni(II), Co(II) has been investigated using Thermogravimetric Analysis (TGA). It was found that pyrolytic
decomposition occurs with melting in metal complexes, and that metal oxides remain as final products. The activation energy
order obtained, E
Cu > E
Ni > E
Co, could be explained on the basis of size of transition metal ion and metal ligand bond strength. In the course of our investigation
on the decomposition of complexes, we carried out a comparative study of different measurement and calculation procedures
for the thermal decomposition. A critical examination was made of the kinetic parameters of non-isothermal thermoanalytic
rate measurement by means of several methods such as Coats–Redfern (CR), Horowitz–Metzger (HM), van Krevelen (vK), Madhusudanan–Krishnan–Ninan
(MKN), and Wanjun–Yuwen–Hen–Cunxin (WYHC). The most appropriate method among these was determined for each decomposition step
according to the least-squares linear regression. It was found that the results obtained using CR method differ considerably
from HM method, as the former method involves a lot of approximations and is not much reliable. The application of thermoanalytic
techniques to the investigation of rate processes has also been discussed. 相似文献
2.
M. R. Prathapachandra Kurup S. V. Chandra K. Muraleedharan 《Journal of Thermal Analysis and Calorimetry》2000,61(3):909-914
Zinc(II), cadmium(II) and mercury(II) complexes of o-vanillin oxime have been synthesized and characterized by different physicochemical techniques. All the complexes have been
subjected to non-isothermal decomposition studies in nitrogen atmosphere using thermogravimetry. The kinetic parameters for
the decomposition of these complexes were evaluated using different methods and comparatively better results were obtained
by these different methods. It has also been found that the decomposition processes of all these complexes follow first order
kinetics.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
N. Sharma A. K. Sood S. S. Bhatt S. C. Chaudhry 《Journal of Thermal Analysis and Calorimetry》2000,61(3):779-785
The thermal decomposition of the complexes [Vcl (acac)2(OAr)] (where acac=2,4-pentanedionato anion; OAr=–OC6H4O-M-4, OC6H4OBut-4) has been studied using non-isothermal techniques (DTA and TG). The TGA indicate that the substitution of chlorine
in VCl2(acac)2 with aryloxide ligands results in an increase in the initial temperature of decomposition (IDT) of the new complexes. The role of the substituent at the aryloxide ring on the thermal stability of the complexes is depicted
and hence described. The ultimate decomposition product in all the complexes has been identified as V2O5. The kinetic and thermodynamic parameters namely, the energy of activation E, the frequency factor A, entropy of activation S and specific reaction rate constant k
r etc. have been rationalized in relation to the bonding aspect of the aryloxide ligands.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
W. S. Lopes Crislene R. S. Morais A. G. Souza V. D. Leite B. D. de A. Firmo 《Journal of Thermal Analysis and Calorimetry》2007,87(3):841-845
Isothermal
decomposition kinetic of three lanthanide mixed complexes with the general
formula of Ln(thd)3phen (where Ln=Nd3+,
Sm3+ or Er3+, thd=2,2,6,6-tetramethyl-3,5-heptanodione and phen=1,10-phenanthroline) has been studied in this
work. The powders were characterized by their melting point, elemental analysis,
FTIR spectroscopy and thermogravimetry. The isothermal TG curves have been
recorded under the same conditions at 265–285, 265–285 and 250–270°C
for Nd(thd)3phen, Sm(thd)3phen
and Er(thd)3phen, respectively.
The kinetic
parameters, i.e. activation energy, reaction order and frequency factor were
obtained through the technique of lineal regression using the relation g(α)=kt+g
0. The analysis was done
at decomposed fractions between 0.10–0.90. The values of activation
energy were: 114.10, 114.24 and 115.04 kJ mol–1
for the Nd(thd)3phen, Sm(thd)3phen
and Er(thd)3phen complexes, respectively. The kinetic
models that best described the isothermal decomposition reaction the complexes
were R1 and R2. The values of activation energy suggests the following decreasing
order of stability: Nd(thd)3phen<Sm(thd)3phen<Er(thd)3phen. 相似文献
5.
I. S. Ahmed 《Journal of Thermal Analysis and Calorimetry》2006,84(2):405-408
The new bridged diacetato–diamido–diamine–uranyl
complex {2[(UO2)(H2N)(H3N)(OOCCH3)]}
was prepared and characterized by elemental analysis, IR measurement as well
as TG and DTA analysis. The kinetic parameters; activation energy (Ea), pre-exponential factor
(A) and the order of decomposition (n) were calculated from TG curves using Coats–Redfern
and Flynn–Wall–Ozawa methods. The mechanism of decomposition has
been established from TG and DTA data. The data obtained agree quite well
with the expected structure and show that the complex finally decomposes to
form UO3. A general mechanism describing the formation
of bridged complex {2[(UO2)(H2N)(H3N)(OOCCH3)]}
is proposed. 相似文献
6.
Shashi B. Kalia Priyanka Sankhyan R. Puri J. Christopher 《Journal of Thermal Analysis and Calorimetry》2012,107(2):597-605
Non-isothermal techniques, i.e. thermogravimetry (TG) and differential scanning calorimetry (DSC), have been applied to investigate
the thermal behaviour of carbaryl (1-naphthyl-N-methylcarbamate = 1-Naph-N-Mecbm) and its complexes, M(1-Naph-N-Mecbm)4X2, where M = Cu, X = Cl, NO3 and CH3COO and M = Zn, X = Cl. Carbaryl and Zn(1-Naph-N-Mecbm)4Cl2 complex exhibit two-stage thermal decomposition while the copper(II) complexes exhibit three and four-stage decomposition
in their TG curves. The nature of the metal ion has been found to play highly influential role on the nature of thermal decomposition
products as well as energy of activation ‘E*’. The presence of different anions does not seem to alter the thermal decomposition patterns. The complexes display weak
to medium intensity exothermic and endothermic DSC curves, while the free ligand exhibits two endothermic peaks. The kinetic
and thermodynamic parameters namely, the energy of activation ‘E*’, the frequency factor ‘A’ and the entropy of activation ‘S*’ etc. have been rationalized in relation to the bonding aspect of the carbaryl ligand. The nature and chemical composition
of the residues of the decomposition steps have been studied by elemental analysis and FTIR data. 相似文献
7.
In this paper, evaluation of kinetic parameters (the activation energy – E,the pre-exponential factor – A and the reaction order – n) with simultaneous determination of the possible reaction mechanism of thermal decomposition of calcium hydroxide (portlandite),
Ca(OH)2 formed during hydration of commercial Portland-slag cement, by means of differential scanning calorimetry (DSC) in non-isothermal
conditions with a single heating–rate plot has been studied and discussed. The kinetic parameters and a mechanism function
were calculated by fitting the experimental data to the integral, differential and rate equation methods.
To determine the most probable mechanism, 30 forms of the solid-state mechanism functions, f(αc) have been tried. Having used the procedure developed and the appropriate program support, it has been established that the
non-isothermal thermal decomposition of calcium hydroxide in the acceleratory period (0.004<αc<0.554) can be described by the rate equation: d αc/dT=A/βexp(−E/RT)f(αc), which is based on the concept of the mechanism reaction:f(αc)=2(αc)1/2.
The mechanism functions as well as the values of the kinetic parameters are in good agreement with those given in literature.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
The effect of thermal treatment at 25–800°C on the structure of some textile dyes (rhodanine' derivatives) has been investigated.
The general formula of these dyes are;[(R)–C6H4–C3NS2O–C5H4N–CH=CH–C6H4N(CH3)2]; 2-[p-dimethylamino-styryl]-6-[5-(3-aryl)-rhodanine]-1,2-dihydropyridine and its derivatives, R=H (I), o-OCH3 (II), p-OCH3 (III) and p-OH (IV). The techniques employed were TG, IR, UV, NMR and elemental analysis. The results showed that the
thermal stability of these dyes depends on the nature of the substituent (R) alkyl radical present and its position in the benzene ring.
On the basis of the application of a non-isothermal kinetic equation, it was found to be a first order reaction. Some kinetic
and thermodynamic parameters for the thermal decomposition process in each stage have been evaluated by the application of
two different calculation methods.
To support the above results a simple quantum study was reported.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Neeraj Sharma Amit Pathania Mala Sharma 《Journal of Thermal Analysis and Calorimetry》2012,107(1):149-154
Thermal behaviour of newly synthesized niobium(V) aryloxides of composition [NbCl5−n
(OC6H4CH(CH3)2-4)
n
] (where n = 1 → 5) synthesized by the reactions of niobium pentachloride with 4-isopropylphenol in predetermined molar ratios in carbon
tetrachloride has been studied by thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The results showed
that thermal decomposition of complex of composition [NbCl4(OC6H4CH(CH3)2-4)] resulted in the formation of NbOCl3 as the ultimate decompositional product while all other complexes yielded Nb2O5 as the final product of thermal decomposition. From the mathematical analysis of TG data, the kinetic and thermodynamic parameters
viz. energy of activation, frequency factor, entropy of activation, etc. have been evaluated using Coats–Redfern equation. 相似文献
10.
Moamen S. Refat 《Journal of Thermal Analysis and Calorimetry》2010,102(3):1095-1103
Three Mn(II), Co(II), and Cu(II) new transition metal complexes of the fluorescence dye: 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole/PBT
derived from o-aminophenol and m-phenylenediamine have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility
and molar conductivity, as well as from mass, IR, UV–Vis spectral studies. From the analytical, spectroscopic, and thermal
data, the stoichiometry of the mentioned complexes was found to be 1:2 (metal:ligand). The molar conductance data revealed
that all the metal chelates are non-electrolytes and the chloride ions exist inside the coordination sphere. The thermal stabilities
of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these three complexes are investigated.
The kinetic parameters such as the energy of activation (E*), pre-exponential factor (A), activation entropy (ΔS*), activation enthalpy (ΔH*), and free energy of activation (ΔG*) have been reported. Photostability of phenyl benzotriazole as fluorescence dye and their metal complexes doped in polymethyl
methacrylate/PMMA were exposed to UV–Vis radiation and the change in the absorption spectra was achieved at different times
during irradiation period. 相似文献
11.
L. Tian N. Ren J. J. Zhang H. M. Liu S. J. Sun H. M. Ye K. Z. Wu 《Journal of Thermal Analysis and Calorimetry》2010,99(1):349-356
The two complexes of [Ln(CA)3bipy]2 (Ln = Tb and Dy; CA = cinnamate; bipy = 2,2′-bipyridine) were prepared and characterized by elemental analysis, infrared
spectra, ultraviolet spectra, thermogravimetry and differential thermogravimetry techniques. The thermal decomposition behaviors
of the two complexes under a static air atmosphere can be discussed by thermogravimetry and differential thermogravimetry
and infrared spectra techniques. The non-isothermal kinetics was investigated by using a double equal-double steps method,
the nonlinear integral isoconversional method and the Starink method. The mechanism functions of the first decomposition step
of the two complexes were determined. The thermodynamic parameters (ΔH
≠
, ΔG
≠
and ΔS
≠
) and kinetic parameters (activation energy E and the pre-exponential factor A) of the two complexes were also calculated. 相似文献
12.
Seema Kothari Vinita Sharma Pradeep K. Sharma Kalyan K. Banerji 《Journal of Chemical Sciences》1992,104(5):583-589
Kinetics of oxidation of aliphatic aldehydes, to the corresponding carboxylic acids, by bis(2,2′-bipyridyl)copper(II) permanganate (BBCP) has been studied. The reaction is first order with respect toBBCP. Michaelis-Menten type kinetics were observed with respect to the aldehyde. The formation constants for the aldehyde-BBCP
complexes and the rates of their decomposition, at different temperatures, have been evaluated. Thermodynamic parameters for
the complex formation and the activation parameters for their decomposition have also been determined. The reaction is catalysed
by hydrogen ions; the acid-dependence being of the form:k
obs = a +b [H+]. The oxidation of MeCDO exhibited a substantial kinetic isotope effect (k
H/k
D = 4.33 at 303 K). The role of aldehyde hydrate in the oxidation process has been discussed. A mechanism involving formation
of permanganate ester and its slow decomposition has been proposed. 相似文献
13.
R. E. Lyon R. N. Walters S. I. Stoliarov 《Journal of Thermal Analysis and Calorimetry》2007,89(2):441-448
The present article describes the synthesis,
structural features and thermal studies of the complexes of the type [M(SB)2(H2O)2]·nH2O [where
HSB=pyridine-m-carboxaldene-o-aminobenzoic
acid and M=Mn(II), Co(II), Ni(II), Cu(II),
Zn(II) and Cd(II)]. The complexes have been characterized on the basis of
elemental analyses, magnetic susceptibility measurements, (FTIR and electronic)
spectra and thermal studies. The nature of the bonding has been discussed
on the basis of infrared spectral data. Magnetic susceptibility measurements
and electronic spectral data suggest a six-coordinated structure of these
complexes. The complexes of Mn(II), Co(II), Ni(II), Cu(II) are paramagnetic,
while Zn(II) and Cd(II) are diamagnetic in nature.
The thermal
decomposition of the complexes have been studied and indicates that not only
the crystallization and coordinated water are lost but also that the decomposition
of the ligand from the complexes is necessary to interpret the successive
mass losses. The kinetic parameters such as order of reaction (n)
and the energy of activation (E
a)
have been reported using Freeman–Carroll method. The entropy (S*), the pre-exponential factor (A),
the enthalpy (H*) and the Gibbs free energy
(G*) have been calculated. 相似文献
14.
S. F. Santos M. C. de Andrade J. A. Sampaio A. B. da Luz T. Ogasawara 《Journal of Thermal Analysis and Calorimetry》2007,87(3):743-746
TiO2–CeO2 oxides
for application as ceramic pigments were synthesized by the Pechini method.
In the present work the polymeric network of the pigment precursor was studied
using thermal analysis. Results obtained using TG and DTA showed the occurrence
of three main mass loss stages and profiles associated to the decomposition
of the organic matter and crystallization. The kinetics of the degradation
was evaluated by means of TG applying different heating rates. The activation
energies (E
a) and
reaction order (n) for each stage were
determined using Horowitz–Metzger, Coats–Redfern, Kissinger and
Broido methods. Values of E
a
varying between 257–267 kJ mol–1 and n=0–1 were found. According to the kinetic
analysis the decomposition reactions were diffusion controlled. 相似文献
15.
Non-isothermal Studies on Mechanism And Kinetics of Thermal Decomposition of Cobalt(II) Oxalate Dihydrate 总被引:1,自引:0,他引:1
B. Małecka E. Drożdż-Cieśla A. Małecki 《Journal of Thermal Analysis and Calorimetry》2002,68(3):819-831
Thermal decomposition of CoC2O4⋅2H2O was studied using DTA, TG, QMS and XRD techniques. It was shown that decomposition generally occurs in two steps: dehydration
to anhydrous oxalate and next decomposition to Co and to CoO in two parallel reactions. Two parallel reactions were distinguished
using mass spectra data of gaseous products of decomposition. Both reactions run according toAvrami–Erofeev equation. For
reaction going to metallic cobalt parameter n=2 and activation energy is 97±14 kJ mol–1. It was found that decomposition to CoO proceeds in two stages. First stage (0.12<αII<0.41) proceeds according to n=2, with activation energy 251±15 kJ mol–1 and second stage (0.45<αII<0.85) proceeds according to parameter n=1 and activation energy 203±21 kJ mol–1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Pérez J. Sánchez G. García J. Serrano J. L. López G. 《Journal of Thermal Analysis and Calorimetry》2001,66(2):361-370
The complex [Pd(2-Phpy)(μ-Cl)]2 reacts with pyridines (L=pyridine, α-picoline and γ-picoline), amines (L=isopropylamine, tert-butylamine) and ammonia to form the corresponding ortho-palladatedderivatives [Pd(2-Phpy)ClL]. The compounds have been characterized by C, H and Nanalyses and spectroscopic methods
(IR and 1H and 13C NMR).TG, DTG and DSC studies of the complexes were carried out in dynamic nitrogen atmosphere. From DSC analyses the heats
of decomposition were calculated. The kinetics ofthe first step of thermal decomposition were evaluated from TG data by isothermal
methods for L=pyridine and isopropylamine. The activation energies obtained are in the range 90–100 kJ mol-1. The best
fitting for data was observed for R2 and A1.5 kinetic models.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
Gerlania S. Silva A. G. Souza J. R. Botelho M. C. D. Silva T. M. S. Silva 《Journal of Thermal Analysis and Calorimetry》2007,87(3):871-874
Cis-norbixin
isomer obtained by hydrolysis of cis-bixin and isolated by solvent extraction
from annatto seeds. The thermal decomposition data of the cis-norbixin samples
were analyzed by thermogravimetric analysis at different heating rates in
the 25–900°C temperature range. DSC curves showed that thermal decomposition
reactions for cis-norbixin occurred in the solid phase. The kinetic parameters,
such as activation energy and pre-exponential factor were determined using
integral and approximate methods: Coats–Redfern, Madhusudanan, Horowitz–Metzger
and Van Krevelen. F1 mechanism describes well the first stage of the thermal
decomposition. 相似文献
18.
Anna Kropidłowska M. Strankowski Maria Gazda Barbara Becker 《Journal of Thermal Analysis and Calorimetry》2007,88(2):463-470
The thermal behavior of Mn(II) silanethiolate series [Mn(SR)2L(MeOH)n],
where R=SSi(OBut)3, L=heterocyclic nitrogen base and n=0,
1 or 2 has been comparatively investigated using differential scanning calorimetry
(DSC), thermogravimetry (TG) and TG-infrared spectoscopy (IR) techniques.
The TG curves indicate the differences in the thermal decomposition due to
presence of distinct N-donor ligands and labile MeOH molecules coordinated
to the central atom. The first step on the TG curves (60–110°C)
corresponds to the elimination of alcohol from respective complexes. The main
step (150–350°C) can be assigned to the decomposition of the complexes
yielding Mn3O4 and silica as
the main final products, identified by X-ray diffraction patterns. 相似文献
19.
New complexes:Zn(Hsalox)(ox), Zn(Hsalox)(NHPh), Zn(Hsalox)(Hsal) and Zn(Hsalox)2(1,2-diMeim) have been synthesised as a result of a reaction of Zn(salox) and Zn(Hsalox)2 (where: salox
2–=OC6H4CHNO2–, Hsalox
–=OC6H4CHNOH–) with 8-hydroxyquinoline (Hox), o-aminophenol (NH2Ph), o-hydroxybenzoic acid (H2Sal) and 1,2-dimethylimidazole (1,2-diMeim). Chemical, X-ray and thermal analyses of the complexes and their sinters have
been carried out. Thermal decomposition pathways have been postulated for the complexes. The mixtures about not definite composition
have been obtained as a result of a reaction of zinc(o-hydroxybenzaldoximates) with imidazole(Him) and 4-methylimidazole (4-MeHim).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
Banjong Boonchom 《Journal of Thermal Analysis and Calorimetry》2009,98(3):863-871
The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO4 · 3H2O was investigated in air atmosphere using TG-DTG-DTA. MgHPO4 · 3H2O decomposes in a single step and its final decomposition product (Mg2P2O7) was obtained. The activation energies of the decomposition step of MgHPO4 · 3H2O were calculated through the isoconversional methods of the Ozawa, Kissinger–Akahira–Sunose (KAS) and Iterative equation,
and the possible conversion function has been estimated through the Coats and Redfern integral equation. The activation energies
calculated for the decomposition reaction by different techniques and methods were found to be consistent. The better kinetic
model of the decomposition reaction for MgHPO4 · 3H2O is the F
1/3 model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”. The thermodynamic functions (ΔH*, ΔG* and ΔS*) of the decomposition reaction are calculated by the activated complex theory and indicate that the process is non-spontaneous
without connecting with the introduction of heat. 相似文献