Correction to: Multistage thermal decomposition in films of cadmium chloride-doped PVA–PVP polymeric blend

Core/shell composites of CuC₂O₄·2H₂O@AP and ZnC₂O₄·2H₂O@AP were prepared from metal oxalates on suspended AP particles in ethanol. CuO and ZnO nano-metal oxides as the nano-catalysts were made from CuC₂O₄·2H₂O and ZnC₂O₄·2H₂O simultaneously by thermal decomposition of AP. The particle size of CuO nano-particles was very finer, and the ZnO particles showed a considerable growth during formation. The kinetic triplet of activation energy, frequency factor, and model of thermal decomposition of pure AP, CuC₂O₄·2H₂O@AP, and ZnC₂O₄·2H₂O@AP composites were estimated by applying three model-free (FWO, KAS, and Starink) and model-fitting (Starink) methods. Based on the thermal analysis, the CuC₂O₄@AP composite has better catalytic performance and the thermal decomposition temperature of AP decreased to about 126.44 °C.     

Magnetic properties of nanocrystalline CuFe2O4 and kinetics of thermal decomposition of precursor

CuFe₂(C₂O₄)₃·4.5H₂O was synthesized by solid-state reaction at low heat using CuSO₄·5H₂O, FeSO₄·7H₂O, and Na₂C₂O₄ as raw materials. The spinel CuFe₂O₄ was obtained via calcining CuFe₂(C₂O₄)₃·4.5H₂O above 400 °C in air. The CuFe₂(C₂O₄)₃·4.5H₂O and its calcined products were characterized by thermogravimetry and differential scanning calorimetry, Fourier transform FT-IR, X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectrometer, and vibrating sample magnetometer. The result showed that CuFe₂O₄ obtained at 400 °C had a saturation magnetization of 33.5 emu g^?1. The thermal process of CuFe₂(C₂O₄)₃·4.5H₂O experienced three steps, which involved the dehydration of four and a half crystal water molecules at first, then decomposition of CuFe₂(C₂O₄)₃ into CuFe₂O₄ in air, and at last crystallization of CuFe₂O₄. Based on KAS equation, OFW equation, and their iterative equations, the values of the activation energy for the thermal process of CuFe₂(C₂O₄)₃·4.5H₂O were determined to be 85 ± 23 and 107 ± 7 kJ mol^?1 for the first and second thermal process steps, respectively. Dehydration of CuFe₂(C₂O₄)₃·4.5H₂O is multistep reaction mechanisms. Decomposition of CuFe₂(C₂O₄)₃ into CuFe₂O₄ could be simple reaction mechanism, probable mechanism function integral form of thermal decomposition of CuFe₂(C₂O₄)₃ is determined to be 1 ? (1 ? α)^1/4.     

Application of isoconversional calculation procedure to non-isothermal kinetics study

The kinetics of thermal decomposition of NH₄CuPO₄·H₂O was studied using isoconversional calculation procedure. The iterative isoconversional procedure was applied to estimate the apparent activation energy E _a; the values of apparent activation energies associated with the first stage (dehydration), the second stage (deamination), and the third stage(condensation) for the thermal decomposition of NH₄CuPO₄·H₂O were determined to be 117.7 ± 7.7, 167.9 ± 8.4, and 217.6 ± 45.5 kJ mol^?1, respectively, which demonstrate 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 _a, A, g(α)]. A new modified method of the multiple rate iso-temperature was used to define the most probable mechanism g(α) of the two stages; and reliability of the used method for the determination of the kinetic mechanism were tested by the comparison between experimental plot and model results for every heating rate. The results show that the mechanism functions of the two stages are reliable. The pre-exponential factor A of the two stages was obtained on the basis of E _a and g(α). Besides, the thermodynamic parameters (ΔS ^≠, ΔH ^≠, and ΔG ^≠) of the two stages were also calculated.     

On the use of electron paramagnetic resonance to implement thermogravimetry data: the thermal decomposition of zinc oxalate dihydrate

The complementary use of thermogravimetric analysis and electron paramagnetic resonance spectroscopy enables the identification on interrelated and successive steps in the vacuum decomposition of ZnC₂O₄ · 2H₂O. After completion of the oxalate dehydration, CO adsorbed species (analogous to those previously reported on MgO) are observed by EPR, starting at a temperature of 250°C. In the temperature range 250–350°C, the CO ad-species disappear while paramagnetic ZnO_1?x and possibly CO^?₄ entities are formed. It is proposed that the latter stems from the reaction of oxygen released by the decomposition of ZnO with CO₂ produced during the oxalate decomposition. Above 300°C, ZnO_1?x and CO^?₄ disappear, leading to the formation of O^3?₃ centers. The latter are gradually decomposed between 350 and 575°C, releasing O₂ observed in EPR as O^?₂ molecular anions and trapped electrons which are again detected as ZnO_1?x. A partially reduced ZnO phase is most probably the end-product of the decomposition.     

Synthesis and thermal decomposition kinetics of Er(III) complex with unsymmetrical Schiff-base ligand

A new unsymmetrical, solid, Schiff base (H₂LLi) was synthesized using L-lysine, o-vanillin and salicylaldehyde. An Er(III) complex of this ligand [Er(H₂L)(NO₃)](NO₃)?·?2H₂O was prepared and characterized by elemental analysis, IR, UV and molar conductance. The thermal decomposition kinetics of the complex for the second stage was studied under non-isothermal conditions by TG and DTG methods. The kinetic equation may be expressed as, dα/dt?=?A?·?e^?E/RT ?·?1/2(1???α)[?ln(1???α)]^?1. The kinetic parameters (E,?A), activation entropy S ^≠ and activation free-energy G ^≠ were also determined.     

草酸锌空心纳米结构的一步固相合成及其表征

本文利用醋酸锌和草酸的一步低热固相化学反应制备了草酸锌空心纳米球，并通过在该反应体系中加入表面活性剂聚乙二醇400得到了草酸锌空心纳米链。采用X-射线粉末衍射（XRD）、透射电镜（TEM）、高倍透射电镜(HRTEM)、扫描电镜(SEM)、红外(IR) 以及热重-差热(TG/DTA)分析对所合成的样品进行了表征.     

Studies on the non-isothermal kinetics of thermal decomposition of the mixed ligand complex — [Fe2O(OC6H4CH=NC6H4O)2(C5H5N)4]·2H2O

The thermal decomposition of the mixed-ligand complex of iron(III) with 2-[(o-hydroxy benzylidene)amino] phenol and pyridine-[Fe₂O(OC₆H₄CH=NC₆H₄O)₂(C₅H₅N)₄]·2H₂O and its non-isothermal kinetics were studied by TG and DTG techniques. The non-isothermal kinetic data were analyzed and the kinetic parameters for the first and second steps of the thermal decomposition were evaluated by two different methods, the Achar and Coats-Redfern methods. Steps 1 and 2 are both second-order chemical reactions. Their kinetic equations can be expressed as: dα/dt=Ae^?E/RT(1-α)²     

CoC2O4·2H2O在空气中的热分解动力学研究

纳米Co3O4具有尖晶石结构,Co3 占据八面体位,具有较高的晶体场稳定化能,在空气中低于800℃时十分稳定,是优良的催化材料[1]。Co3O4还可以作为高比能锂离子电池负极材料具有非常好的电化学活性,充放电容量高达960m A h·g-1。纳米Co3O4在紫外、可见及近红外区域都有良好的吸收效果,因此,在隐身技术、保温节能技术等领域具有潜在的应用前景。所以,Co3O4超细粉体的制备和应用研究具有十分重要的意义。我们合成了草酸盐先驱物制备纳米Co3O4用作隐身材料,因此对先驱物的热分解过程研究是十分必要的。热分析方法在了解先驱物热分解反应的物理…     

Selective self-assembly synthesis of MnV2O6·4H2O with controlled morphologies and study on its thermal decomposition

The MnV₂O₆·4H₂O with rod-like morphologies was synthesized by solid-state reaction at low heat using MnSO₄·H₂O and NH₄VO₃ as raw materials. XRD analysis showed that MnV₂O₆·4H₂O was a compound with monoclinic structure. Magnetic characterization indicated that MnV₂O₆·4H₂O and its calcined products behaved weak magnetic properties. The thermal process of MnV₂O₆·4H₂O experienced three steps, which involves the dehydration of the two waters of crystallization at first, and then dehydration of other two waters of crystallization, and at last melting of MnV₂O₆. In the DSC curve, the three endothermic peaks were corresponding to the two steps thermal decomposition of MnV₂O₆·4H₂O and melting of MnV₂O₆, respectively. Based on the Kissinger equation, the average values of the activation energies associated with the thermal decomposition of MnV₂O₆·4H₂O were determined to be 55.27 and 98.30?kJ?mol^?1 for the first and second dehydration steps, respectively. Besides, the thermodynamic function of transition state complexes (??H ^??, ??G ^?? , and ??S ^?? ) of the decomposition reaction of MnV₂O₆·4H₂O were determined.     

Synthesis, structure analysis and thermodynamics of [Ni(H2O)4(TO)2](NO3)2·2H2O (TO = 1,2,4-triazole-5-one)

A novel complex [Ni(H₂O)₄(TO)₂](NO₃)₂·2H₂O (TO = 1,2,4-triazole-5-one) was synthesized and structurally characterized by X-ray crystal diffraction analysis. The decomposition reaction kinetic of the complex was studied using TG-DTG. A multiple heating rate method was utilized to determine the apparent activation energy (E _a) and pre-exponential constant (A) of the former two decomposition stages, and the values are 109.2 kJ mol^?1, 10^13.80 s^?1; 108.0 kJ mol^?1, 10^23.23 s^?1, respectively. The critical temperature of thermal explosion, the entropy of activation (ΔS ^≠), enthalpy of activation (ΔH ^≠) and the free energy of activation (ΔG ^≠) of the initial two decomposition stages of the complex were also calculated. The standard enthalpy of formation of the new complex was determined as being ?1464.55 ± 1.70 kJ mol^?1 by a rotating-bomb calorimeter.     

Synthesis,thermal, spectral and biological properties of zinc(II) 4-hydroxybenzoate complexes

New zinc(II) 4-hydroxybenzoate complex compounds with general formula [Zn(4-OHbenz)₂L_n]·xH₂O, where 4-OHbenz = 4-hydroxybenzoate; L = isonicotinamide, N-methylnicotinamide, N,N-diethylnicotinamide, thiourea, urea, phenazone, theophylline, methyl-3-pyridylcarbamate; n = 2, 3; x = 0–3, 5, were synthesized and characterised by elemental analysis, thermal analysis and IR spectroscopy. The thermal behaviour of the prepared compounds was studied by TG/DTG and DTA methods in argon atmosphere. The thermal decomposition of hydrated compounds started with dehydration. During the thermal decomposition, organic ligand, carbon monoxide, carbon dioxide and phenol were evolved. The final solid product of the thermal decomposition was zinc or zinc oxide. The volatile gaseous product, solid intermediate products and the final product of thermal decomposition were identified by IR spectroscopy, mass spectrometry, qualitative chemical analyses and X-ray powder diffraction method. The antimicrobial activity of zinc(II) carboxylate compounds was tested against various strains of bacteria, yeasts and filamentous fungi (S. aureus, E. coli, C. parapsilosis, R. oryzae, A. alternata, M. gypseum). The presence of zinc in complexes led to the increase in their antimicrobial activity in comparison with free 4-hydroxybenzoic acid.     

Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

The following Zn(II) complexes of deprotonated 6-amino-5-nitrosouracil (AH), 6-amino-3-methyl-5-nitrosouracil (BH) and 6-amino-1-methyl-5-nitrosouracil (CH) have been prepared and their thermal behaviour studied by TG and DSC techniques: ZnA₂(H₂O)₂, ZnB₂ · 4 H₂O, ZnC₂ · 4 H₂O and ZnC₂(H₂O)₂ · H₂O. The values of the dehydration enthalpy of the complexes are in the 31.3–76.5 kJ mol^?1 H₂O range and, except in the first complex, the dehydration processes take place in several steps. The pyrolysis of the complexes finishes between 540 and 725° C ZnO remaining as residue.     

Synthesis,non-isothermal kinetic and thermodynamic studies of the formation of LiMnPO4 from NH4MnPO4·H2O precursor

NH₄MnPO₄·H₂O was successfully synthesized by precipitating method. The LiMnPO₄ was successfully generated through solid state reaction between synthesized NH₄MnPO₄·H₂O precursor and Li₂CO₃. The morphologies were observed to depend on the reaction temperatures. The thermal decomposition of NH₄MnPO₄·H₂O and the formation process of LiMnPO₄ were confirmed by TG/DTG/DTA, FTIR, AAS/AES, XRD and SEM methods. The average crystallite size of NH₄MnPO₄·H₂O, Mn₂P₂O₇ and LiMnPO₄ were found to be around 51.2, 44.9 and 48.1 nm, respectively. The non–isothermal kinetic parameters (kinetic triplet: E_α, A, g(α)) of the formation process of LiMnPO₄ were evaluated from TG data by using Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose methods. The iterative methods of both equations were carried out to determine the exact values of E_α. The Coats–Redfern equation and kinetic compensation effects were successfully applied to confirm the activation energy and the most probable mechanism functions of the formation of LiMnPO₄. The thermodynamic functions (ΔH^≠, ΔS^≠, ΔG^≠) of the transition state complexes of the formation of LiMnPO₄ were calculated from the kinetic parameters for the first time.     

Products and kinetics of non-isothermal decomposition of vanadium(IV) oxide compounds

The kinetics of dehydration and decomposition of VOSO₄·2H₂O, VOSO₄ and VOSeO₃·H₂O was studied under non-isothermal heating on a derivatograph. The stages and products of the thermal decomposition were determined. It was proved that VOSO₄·2H₂O decomposes to V₂O₅ while VOSeO₃·H₂O − to V₂O₄. A number of kinetic models and calculation procedures were used to determine the values of the kinetic parameters characterizing the process. The parameters calculated were compared and analyzed. IR-spectra of the initial substances and the solid residue after decomposition are presented.     

The kinetic parameters of thermal decomposition hydrated iron sulphate

The thermal decomposition of iron sulphate hexahydrate was studied by thermogravimetry at a heating rate of 5°C min^?1 in static air. The kinetic parameters were evaluated using the integral method by applying the Coats and Redfern approximation. The thermal stabilities of the hydrates were found to vary in the order. Fe₂(SO₄)₃·6H₂O → Fe₂(SO₄)₃·4.5H₂O → Fe₂(SO₄)₃·0.5H₂O The dehydration process of hydrated iron sulphate was found to conform to random nucleation mass loss kinetics, and the activation energies of the respective hydrates were 89.82, 105.04 and 172.62 kJ mol^?1, respectively. The decomposition process of anhydrous iron sulphate occurs in the temperature region between 810 and 960 K with activation energies 526.52 kJ mol^?1 for the D3 model or 256.05 kJ mol^?1 for the R3 model.     

Physico-chemical characterization of thermal decomposition course in zinc nitrate-copper nitrate hexahydrates

This study reports experimental investigations by non-isothermal TG/DSC analysis of Zn(NO₃)₂·4H₂O, Cu(NO₃)₂·4H₂O and their mixtures of known compositions in the temperature range 30–1200°C. Solid/liquid transitions in the sealed samples of the hexahydrate salts and their mixtures were also studied by DSC in the temperature range 0–60°C. The mixture with composition 0.85Zn(NO₃)₂·6H₂O+0.15Cu(NO₃)₂·6H₂O showed single melting peak at 29°C. This mixture was chosen for detailed studies. Melting temperature and heat of fusion of single salt hexahydrates and of the mixture were calculated from DSC endotherms. The different stages in the thermal decomposition processes have been established. The intermediate and the final solid products of the thermal decomposition were analyzed by XRD. The scheme and the decomposition temperature depended on the composition of the starting material. The final decomposition products were CuO (monoclinic), Cu₂O (cubic), ZnO (hexagonal) and their mixtures with the defined crystalline structures. Possible influence of the addition of CuCl₂·2H₂O into the mixture 0.85Zn(NO₃)₂·6H₂O+0.15Cu(NO₃)₂·6H₂O and a gel combustion technique of the precursor preparation, on the composition and morphology of the solid decomposition products, were also studied. The gel combustion technique, using citric acid added to a mixture of 0.85Zn(NO₃)₂·6H₂O+0.15Cu(NO₃)₂·6H₂O, was applied in an attempt to obtain mixed Zn/Cu oxides of a particular mole ratio. The morphology of the solid decomposition products was examined by SEM.     

Synthesis and thermal decomposition of neodymium(III) peroxotitanate to Nd<Subscript>2</Subscript>TiO<Subscript>5</Subscript>

Neodymium(III) peroxotitanate is used as a precursor for obtaining Nd₂TiO₅. The last one possesses numerous valuable electrophysical properties. TiCl₄, Nd(NO₃)₃·6H₂O and H₂O₂ in mol ratio 1:2:10 were used as starting materials. The reaction ambience was alkalized to pH = 9 with a solution of NH₃. The obtained neodymium(III) peroxotitanate and intermediate compounds of the isothermal heating were proved by the help of quantitative analysis and infrared spectroscopy (IRS). It has Nd₄[Ti₂(O₂)₄(OH)₁₂]·7H₂O composition. The absorption band observed in IRS at 831 cm^?1 relates to a triangular bonding of the peroxo group of Ti, at 1062 cm^?1—terminal groups Ti–OH and at 1491 and 1384 cm^?1—the bridging OH^?-groups Ti–O(H)–Ti. Nd₂TiO₅ was obtained by thermal decomposition of neodymium(III) peroxotitanate. The isothermal conditions for decomposition were determined on the base of differential thermal analysis, thermogravimetric and differential scanning calorimetry results in the temperature range of 20–1000 °C. The mechanism of thermal decomposition of Nd₄[Ti₂(O₂)₄(OH)₁₂]·7H₂O to Nd₂TiO₅ was studied. In the temperature range of 20–208 °C, a simultaneous decomposition of the peroxo groups by the separation of oxygen and hydrate water is conducted and Nd₄[Ti₂O₄(OH)₁₂] is obtained. From 208 to 390 °C, the terminal OH^?-groups are separated and Nd₄[Ti₂O₇(OH)₆] is formed. In the range of 390–824 °C, the bridging OH^?-groups are completely decomposed to Nd₂TiO₅. The optimal conditions for obtaining nanocrystalline Nd₂TiO₅ are 900 °C for 6 h and 20–80 nm.     

Thermoanalytische und massenspektrometrische Untersuchung der Zersetzung von Zinkoxalat-Dihydrat. Thermoanalytische Untersuchungen XII

The dehydration and pyrolysis of zinc oxalate dihydrate are re-examined by thermo-analytical methods at linearily increasing temperature in air, nitrogen, water vapour, and high vacuum. Simultaneous analysis of the gaseous decomposition products by means of mass spectrometry confirms previous authors' results obtained with other methods. The activation energy of the thermal decomposition of ZnC₂O₄ above 340° has been found to be 40,4 ± 2,6 kcal/mol. The rehydration of ZnC₂O₄ has been investigated at various water vapour pressures. In an atmosphere virtually saturated with moisture, the rehydration leads to the dihydrate and is easily controlled on the thermobalance. The dihydrate itself takes up an ill-defined fraction of surplus water. The thermal effects resulting from surface water on the dihydrate have been investigated by DTA (freezing and melting peaks). They disappear below 5% w/w of surplus water in the dihydrate. The surface of cristallites of the decomposition products calculated from particle size (from X-ray line broadening) is much larger than the surface determined by the BET-method. However, for ZnO in its state immediately after decomposition of ZnC₂O₄, both methods give similar results. Thus, dihydration of ZnC₂O₄ · 2 H₂O produces a considerable inner surface of ZnC₂O₄ not accessible to gas adsorption. This surface is considered to be covered by adsorbed water, which would explain the remarkable amount of water retained during dehydration. The final product, ZnO, sinters rapidly at temperatures higher than 500–600°.     

Dehydration Kinetics of Zinc Phosphate Tetrahydrate α-Zn3（PO4）2·4H2O Nanoparticle

TG-DTG technique and Harcourt-Esson integrated equation were used to study the dehydration process of zinc phosphate tetrahydrate α-Zn3（PO4）2·4H2O nanoparticle and its thermal decomposition kinetics. The results show that there are three stages of dehydration between 300 and 800 K during the thermal decomposition of α-Zn3（PO4）2·4H2O nanoparticle. The first stage is controlled by chemical reaction with an activation energy of 69.48 kJ·mol^-1 and a pre-exponential factor of 1.77×10^6 s^-1. The second is controlled by nucleation and growth with an activation energy of 78.74 kJ·mol^-1 and a pre-exponential factor of 5.86×10^9 s^-1. The third is controlled by nucleation and growth with an activation energy of 141.5 kJ·mol^-1 and a pre-exponential factor of 1.01×10^12 s^-1. The kinetic compensative effects not only exist in Arrhenius equation but also in Harcourt-Esson equation. Activation energy E is dependent on both the decomposition fraction α and temperature T.     

Study on thermal decomposition and oxidation kinetics of cation exchange resins using non-isothermal TG analysis

Kinetics of two successive thermal decomposition reaction steps of cationic ion exchange resins and oxidation of the first thermal decomposition residue were investigated using a non-isothermal thermogravimetric analysis. Reaction mechanisms and kinetic parameters for three different reaction steps, which were identified from a FTIR gas analysis, were established from an analysis of TG analysis data using an isoconversional method and a master-plot method. Primary thermal dissociation of SO₃H⁺ from divinylbenzene copolymer was well described by an Avrami–Erofeev type reaction (n = 2, g(α) = [?ln(1 ? α)]^1/2]), and its activation energy was determined to be 46.8 ± 2.8 kJ mol^?1. Thermal decomposition of remaining polymeric materials at temperatures above 400 °C was described by one-dimensional diffusion (g(α) = α ²), and its activation energy was determined to be 49.1 ± 3.1 kJ mol^?1. The oxidation of remaining polymeric materials after thermal dissociation of SO₃H⁺ was described by a phase boundary reaction (contracting volume, g(α) = 1?(1 ? α)^1/3). The activation energy and the order of oxygen power dependency were determined to be 101.3 ± 13.4 and 1.05 ± 0.17 kJ mol^?1, respectively.