Effect of gamma-radiation on thermal decomposition of bis(diethylene triamine)cobalt(II) nitrate and bis(diethylene triamine)zinc(II) nitrate

Effect of γ-radiation on non-isothermal decomposition kinetics of bis(diethylene triamine)cobalt(II) nitrate and bis(diethylene triamine)zinc(II) nitrate have been studied in nitrogen atmosphere at a heating rate of 10 °C/minute. The data were analyzed by Coats- Redfern, Freeman-Caroll and Horowitz-Metzeger methods. The result showed that irradiation enhanced thermal decomposition in both the complexes. Activation energy and associated kinetic parameters are lowered upon irradiation and the extent of lowering is higher in cobalt complex compared to zinc complex. Order of the reaction for each step was found to be unity. The mechanism for deamination and decomposition is controlled by R₂ function except for the deamination of unirradiated cobalt complex where the process is governed by R₃ function.     

Thermoanalytical investigations on kinetics and mechanism of deamination of tris(ethylenediamine)copper(II) sulphate

The thermal decomposition of tris(ethylenediamine)copper(II) sulphate has been studied using TG, DTG and DTA. The different stages of decomposition have been identified by these techniques in conjunction independent pyrolysis and X-ray diffraction. The kinetics and mechanism of the first two stages of deamination of the complex were evaluated. The activation parameters for the deamination reaction were computed from the TG and DTA curves using four integral methods. The two stages of deamination follow the mechanism of random nucleation with the formation of one nucleus on each particle (Mampel equation). The thermodynamic parameter namely heat of reaction (DH) for the two deamination processes was also evaluated.

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Zusammenfassung Mittels TG, DTG und DTA wurde die thermische Zersetzung von Tris(ethylendiamin)-kupfer(II)-sulfat untersucht. Anhand dieser Methoden wurden in Verbindung mit einer gesonderten Pyrolyse und Röntgendiffraktion die einzelnen Schritte dieser Zersetzung identifiziert. Weiterhin wurde die Kinetik und der Mechanismus der beiden ersten Schritte der Desaminierung des Komplexes entwickelt. Unter Anwendung von vier Integralmethoden wurden aus den TG- und DTA-Kurven die Aktivierungsparameter der Desaminierungsreaktion berechnet. Beide Schritte der Desaminierung verlaufen nach dem Mechanismus der Random-Keimbildung mit der Bildung von einem Keim pro Partikel (Mampel-Gleichung). Die Reaktionswärme der zwei Desaminierungsprozesse wurde ebenfalls bestimmt.

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The authors are grateful to the authorities of Vikram Sarabhai Space Centre for providing the instrumental facilities. The help of Dr. K. Krishnan and Mr. Viswanathan Asari in the TG/DTA instrumental work is gratefully appreciated. One of the authors (S.M.) acknowledges with gratitude the aid given to him by the Council of Scientific and Industrial Research (India) in the form of a senior research fellowship for carrying out this work.     

Influence of polyesterurethane plasticizer on the kinetics of poly(vinyl chloride) decomposition process

Poly(vinyl chloride) (PVC), plasticized by di(2-ethylhexyl) phthalate (DEHP), medium molecular mass polyesterurethane (PU) or by both plasticizers, was thermally degraded under dynamic thermogravimetric conditions and the kinetics of decomposition was studied by isoconversional methods and by non-linear regression. It has been found that the initial decomposition temperature is higher for PVC plasticized with PU, as compared with PVC plasticized with di(2-ethylhexyl) phthalate (DEHP) or plasticized with PU/DEHP, and thermal degradation shows features of a multi-step complex process. Application of polymeric plasticizer leads to the increase and a 'smoothing' effect in the course of energy of activation and pre-exponential factor at the initial stage of decomposition indicating thus the hindered migration of medium molecular mass compound from PVC matrix (in comparison with PVC containing monomeric DEHP) due to steric hindrances as well as due to specific interactions between C=O and Cl groups along the macrochains. Kinetic model function of the decomposition process of PVC/DEHP and PVC/DEHP/PU blends was found to be a two-stage autocatalyzed reaction of n^th order; autocatalytic effect is associated most likely with the role of HCl formed during PVC decomposition. For PVC/PU blend best fit was found by non-linear regression for a two-stage scheme in which first stage was Prout-Tompkins model and the second was autocatalytical model of n^th order - the first one involves particle disintegration, which was promoted by product generation at branching PVC 'pseudo-crystals' nuclei, thus exposing more surface on which decomposition reaction proceeds.     

Thermal Behavior of Zn(Thr)SO_4·H_2O

IntroductionRecently,a considerable interest has been fo-cused on the complexes of zinc with amino acidsdue to their excellent additives in medicine foodstuff and cosmetics[1— 6] .The investigation on thethermal behavior and the thermochemistry of somezinc amino acids is important to its further applica-tion,which has been reported in references[4,5 ,7— 1 0 ].However,the studies on solid complexZn( Thr) SO4· H2 O has not been reported,whichcan provide the necessary data and the foundation…     

Thermal decomposition studies of [Ni(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]X<Subscript>2</Subscript> (X = Cl,Br) in the solid state using TG-MS and TR-XRD

Detailed investigation on the thermal behaviour of hexaamminenickel(II) chloride and hexaamminenickel(II) bromide has been carried out by means of simultaneous TG/DTA coupled online with mass spectroscopy (TG-MS) and temperature-resolved X-ray diffraction (TR-XRD). Evolved gas analyses by TG-MS revealed the presence of NH₂, NH, N₂ and H₂ fragments in addition to ammonia during the deamination process. These transient species resulted due to the fragmentation of the evolved ammonia during pyrolysis. The intermediates formed during the thermal deamination stages were monitored by in situ TR-XRD. The final product of the decomposition was found to be nano size metallic nickel in both cases. Morphology of the complexes, intermediates and the residue formed at various decomposition stages was analysed by scanning electron microscope (SEM). Kinetic analyses using isoconversional method for deamination and dehalogenation reaction show that the activation energies vary with the extent of conversion, indicating the multi-step nature of these solid state decomposition reactions.     

Kinetics of the non-isothermal decomposition of Cu-and Co-itaconato complexes

The kinetics of the thermal decomposition of Cu- and Co-itaconato complexes were studied using dynamic thermogravimetric techniques. The dehydration process was found to proceed in a one-stage reaction, while the thermal decomposition of the anhydrous salts was followed a two-stage reaction. The first stage is the decomposition of the complex to metal carbonate, whereas the second stage is the decomposition of the formed carbonate to the oxide. Kinetic analysis of the dynamic TG curves were discussed with reference to a composite integral method on comparison with the integral methods of Coats and Redfern and Ozawa. The activation parameters were calculated and discussed for each decomposition step.     

Thermal behaviour of Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) complexes with isatin-β-thiosemicarbazone

The isatin-β-thiosemicarbazone (ITC) complexes of Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) were prepared and characterized by elemental analysis, as well as molar conductivity, magnetic susceptibility, FTIR, UV-Vis and ¹H NMR spectroscopic methods. The complexes were also studied for its thermal stability. They all behaviour as anhydrous complexes and its thermolysis passes through the stages of deamination (517–547 K) and complete thermal decomposition (619–735 K).     

Eu_2(p-ClC_6H_4COO)_6(C_(12)H_8N_2)_2配合物热分解机理及非等温动力学

0 IntroductionThe complexes formed by rare earth and aromatic carboxylic acid have many special structuresand interesting luminous properties, thus arouse people's interest to study them. They can be used.in many areas such as extraction and separation, germicide, catalyst, luminous materials andfunctional materials and so on.The crystal structure and luminescence spectra of the europium p-chlorobenzoate complex withl, 10-phenanthroline has been reported"], but the study for its non-isothermal…     

Thermal and spectroscopic investigation of new binuclear Pt(II) complexes with carboxylic acids

The thermal decomposition of the binuclear Pt(II) complexes with acetate, propionate, valerate and izovalerate ligands were studied by TG and DTA techniques. The Pt(II) complex with acetic acid (PtAA) was stable up to 343.15 K, Pt(II) complex with propionic acid (PtPrA) was stable up to 323.15 K, Pt(II) complex with valeric acid (PtVA) was stable up to T=313.15 K and Pt(II) complex with isovaleric acid (PtIvA) was stable up to 408.15 K. The PtAA complex was investigated again after a year by thermogravimetric analysis. After the thermal decomposition of the Pt(II) complexes with carboxylic acids, only in the PtVA complex and PtAA complex (investigated after a year) the final residue contains only platinum, while in the rest complexes the solid residue was a mixture of platinum and platinum carbides (PtC₂, Pt₂C₃).     

Crystal structure and thermoanalytical study of a manganese(II) complex with 1-allylimidazole

The crystal structure of a manganese(II) 1-allylimidazole complex ([Mn(1-AIm)₃(NO₃)₂], where 1-Aim=1-allylimidazole), was characterized by X-ray diffraction (XRD) using SHELX-97. The thermal behaviour of the complex was investigated by thermogravimetry (TG) coupled with an FTIR unit. The complex showed a multi-step decomposition related to the release of the ligand molecules, followed by oxidation. The final residue at 1073 K was found to be manganese(II) oxide. Evolved gas analysis allowed to prove the oxidative decomposition pattern of the examined complex, initially proposed by the percentage mass loss data. Finally, a kinetic analysis of the oxidative decomposition steps was made using the Kissinger equation, while the complex nature of the decomposition kinetics was revealed by the isoconversional Ozawa-Flynn-Wall method.     

Study of the thermal decomposition on Pt(II) complexes with cycloalkanespiro-5′-hydantoins

The thermal decomposition of the Pt(II) complexes with cyclobutane-and cycloheptanespiro-5′-hydantoins were studied by TG and DTA techniques. The Pt(II) complex with cyclobutanespiro-5′hydantoin (PtCBH) was stable up to 115°C (388 K) and Pt(II) complex with cycloheptanespiro-5′-hydantoin (PtCHTH) was stable up to 150°C (423 K). After the thermal decomposition of PtCBH the solid residue was platinum, while the decomposition of PtCHTH gave a mixture of platinum carbides (PtC₂, Pt₂C₃).     

Thermogravimetric Analysis of Cobalt(II)-dothiepin Complexes

The complexes of cobalt(II) with dothiepin (DOT) hydrochloride have been studied for kinetics of thermal degradation by thermogravimetric analysis (TG) and derivative thermogravimetric studies (DTG) in a static nitrogen atmosphere at a heating rate of 10° C min⁻¹. A general mechanism of thermal decomposition is advanced involving dehydration and decomposition process for both organic and inorganic ligands. The thermal degradation reactions were found to proceed in three steps having an activation energy in the range 6.75–170 kJ mol⁻¹. Thermal decomposition kinetics parameters were computed on the basis of thermal decomposition data. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decomposition of mixed ligand complexes of cobalt(II), nickel(II), zinc(II) and cadmium(II) containing 1,3-diaminopropan-2-ol and oxalate

Non-isothermal kinetics of the thermal decomposition of mixed ligand complexes of cobalt(II), nickel(II), zinc(II) and cadmium(II) have been studied using thermogravimetry (TG) and differential scanning calorimetry (DSC). The reaction in which the complex loses one molecule of the ligand is found to be first order and the activation energy was calculated using established techniques. Using Dharwadkar and Karkhanavala's method, the values obtained were 25.65, 17.32, 25.22 and 20.95 kcal mole^?1, respectively. Infrared spectral studies of these complexes and intermediates provided information regarding the coordinating nature of the ligand 1,3-diaminopropan-2-ol in these complexes.     

N,N′-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺在空气中的热分解动力学研究

以TG-DTG为手段, 研究了N,N′-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺(DPTDEDA)在空气中的热分解动力学,利用Friedman法、Flynn-Wall-Ozawa(FWO)法对DPTDEDA进行了动力学分析, 求出了该物质两个主要的热分解阶段的热分解动力学参数, 同时利用Coats-Redfern法、Achar法研究了该物质的热分解机理. 结果表明, 用Friedman法所求得的两个热分解阶段的表观活化能的平均值分别为128.03和92.59 kJ•mol^－1; 而Flynn-Wall-Ozawa法所求得的两个热分解阶段的表观活化能的平均值分别为138.75和106.78 kJ•mol^－1. 由Coats-Redfern法、Achar法得出DPTDEDA在空气中的热分解过程虽主要分为两段反应, 但经过推理其反应机理函数却是相同的, 为f(α)＝3/2(1－α)^4/3[(1－α)^－1/3－1]^－1.     

Polymerization of acrylonitrile initiated by thiourea-vanadium(V) redox system

The kinetics of polymerization of acrylonitrile initiated by V⁵⁺-thiourea or V⁵⁺-ethylene thiourea have been studied at 30, 35 and 40°C in nitrogen. The rates of polymerization and V⁵⁺ disappearance, and the chain lengths of polymers were measured. The kinetics are consistent with the formation of an intermediate complex between the thiol form of thiourea or ethylene thiourea and the oxidant decomposition of which leads to the initiating radical. The effects of certain organic solvents (water miscible) and salts on the rate of polymerization have been studied. A kinetic scheme has been proposed and the various rate and energy parameters evaluated.     

Thermal decomposition of microbial poly(γ-glutamic acid) and poly(γ-glutamate)s

The thermal decomposition of poly(γ-glutamic acid), poly(α-methyl γ-glutamate) and ionic complexes of the polyacid with alkyltrimethyl ammonium salts was studied by TGA, GPC, and FTIR and NMR spectroscopies. It was found that both poly(γ-glutamic acid) and poly(α-methyl γ-glutamate) depolymerised above 200 °C by unzipping mechanism with generation of pyroglutamic acid and methyl pyroglutamate, respectively. On the other hand, the ionic complexes degraded through a two-stage process, the first stage being cyclodepolymerisation of the poly(γ-glutamate) main chain along with decomposition of the ionic complex promoted by the adsorbed water. Decomposition of the previously generated alkyltrimethyl ammonium compound followed by unspecific cracking of the resulting nitrogenated compounds accounted for the second degradation step, at higher temperatures. Mechanisms explaining the decomposition of the three studied systems were proposed according to collected data.     

Eu2(p-ClC6H4COO)6(C12H8N2)2配合物热分解机理及非等温动力学

The thermal decomposition behaviour of europium p-chlorobenzoate complex with 1, 10-phenanthroline and its kinetics were studied in nitrogen by non-isothermal thermogravimetry.Its thermal decomposition occurs mainly in three steps..The intermediate and residue for each step of decomposition were identified from TGcurve.The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method.the Madhusudanan- Krishnan-Niman (MKN) method and Ozawa method respectively.The most probable mechanisms function for the first and second stage were suggested by comparing the kinetic parameters.     

双核Cu(I)配合物的热分解非等温动力学

Thermal decomposition process of four benzimidazolyl-containing dicopper(Ⅰ) complexes: [Cu2(OCTB)](ClO4)2•1.5H2O(1), [Cu2 (NMOCTB)](ClO4)2•H2O(2), [Cu2(NBUOCTB)](ClO4)2(3), [Cu2(NBOCTB)](ClO4)2•H2O(4) and their kinetics were studied under the non-isothermal conditions by TG-DTG techniques. The non-isothermal kinetic data were analyzed by means of Achar and Coats-Redfern method respectively. The kinetic equation for the second step of the decomposition of complex (1) can be expressed as: dα/dt=A•exp(-E/RT) •(1-α), the mechanism of this reaction corresponds to "Coring and Growth" with n=1; while for the first step of complex (3) decomposition, dα/dt=A•exp(-E/RT)• (1-α)2, which corresponds to the mechanism of "the second-order chemical reaction".     

DSC kinetics of the thermal decomposition of copper(II) oxalate by isoconversional and maximum rate (peak) methods

The copper(II) oxalate was synthesized, characterized using FT-IR and scanning electron microscopy and its non-isothermal decomposition was studied by differential scanning calorimetric at different heating rates. The kinetics of the thermal decomposition was investigated using different isoconversional and maximum rate (peak) methods viz. Kissinger–Akahira–Sunose (KAS), Tang, Starink^1.95, Starink^1.92, Flynn–Wall–Ozawa (FWO) and Bosewell. The activation energy values obtained from isoconversional methods of FWO and Bosewell are 0.9 and 3.0 %, respectively, higher than that obtained from other methods. The variation of activation energy, E _α with conversion function, α, established using these different methods were found to be similar. Compared to the FWO method, the KAS method offers a significant improvement in the accuracy of the E _a values. All but the Bosewell maximum rate (peak) methods yielded consistent values of E _α (~137 kJ mol^?1); however, the complexity of the thermal decomposition reaction can be identified only through isoconversional methods.     

Kinetics of Thermal Decomposition of Copper(II) Acetate Monohydrate

The thermal decomposition of copper(II) acetate monohydrate was studied in air and nitrogen atmospheres by means of DTA-TG and SEM measurements. The kinetics of the thermal decomposition steps in air was studied by using isothermal and non-isothermal thermogravimetric techniques. The results are discussed in terms of various reaction interface models and different techniques of computational analysis of non-isothermal data. The activation parameters, calculated by using a composite method of integral analysis of non-isothermal data, revealed not only their independence from the heating rate and fractional reaction, but also a better correlation and agreement with the results obtained under isothermal conditions. This revised version was published online in July 2006 with corrections to the Cover Date.