Dynamic Air Atmosphere Research Articles

Crystal chemistry and thermal behavior of metal salts and complexes of unsaturated dicarboxylic acids: aquabis(hydrogen itaconato)barium(II), [Ba(C5H5O4)2(OH2)

[Ba(C5H5O4)2(OH2)] is monoclinic, C2/c, with a = 4.472(1), b = 13.312(3), c = 22.236(5) A, β= 92.90(1)°, Z = 4, and Dm = 2.06 g cm−3. The barium atom is 10-coordinate with Ba—O distances in the range 2.749(2)–2.989(2) A. The material suffers a complex decomposition process upon heating at temperatures between 25 and 600°C in dynamic nitrogen and static air atmospheres. FT-IR and gas chromatography analyses indicate that water, CO, CO2, methane, ethane, ethylene, propane, propylene, and butane, are evolved during the heating process, leaving a residue of BaCO3. 1H-NMR spectra of a sample heated at 200°C, showed isomerization of barium itaconate to barium methylmaleate.

Air oxidation of Beypazari lignite at 50°C, 100°C and 150°C

Structural changes occurred in Beypazari lignite while oxidizing at 50°C, 100°C and 150°C in a dynamic air atmosphere was detected by infrared spectroscopy. Relative changes in the amount of various oxygenated functional groups with respect to time were determined by curve resolution procedures. Investigation of the spectra of the samples at different oxidation conditions reveal that as the duration and temperature of the oxidation reactions increased the absorption in the aliphatic C–H stretching region decreased, while the absorption in the CO stretching region presented a significant increase.

Thermal and infrared spectroscopic characterization of historical mortars

The characterization of historical mortars was performed by thermal analysis (TG-DTG), simultaneous infrared spectroscopy (TG-FTIR) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The samples were taken from St. John Church (Tartu, Estonia), built in the 13th–14th centuries. The analyses are important for the restoration of the church. In reality, mortar is a very difficult system, the lime is accompanied with different hydraulic components. TG-DTG analysis and FTIR methods can be used to identify various components of mortar and to observe the reactions associated with the controlled heating at 25–900°C in dynamic air and nitrogen atmosphere. The elemental composition of the acid-soluble components (ASC) was determined by using the ICP-AES techniques.

Synthesis and thermal behaviour of pentamethylcyclopentadienylrhodium(III) complexes with anilines

The complex [RhCp∗Cl(μ-Cl)] 2 ( Cp∗ = C 5 Me 5 ) reacts with RNH 2 (R = C 6H 5, p-CH 3C 6H 4, p-CH 3OC 6H 4, p-ClC 6H 4 and p-BrC 6H 4) in dichloromethane to form the corresponding pentamethylcyclopentadienylrhodium(III) derivatives [RhCp∗Cl 2(RNH 2)]. The compounds have been characterized by C, H and N analyses and spectroscopic methods (IR and 1H NMR). The TG, DTG and DSC study of the complexes was carried out in both dynamic nitrogen and air atmospheres. From the DSC curves the heat of decomposition was calculated. The kinetics of the first step of thermal decomposition were evaluated from TG data by means of Coats-Redfern, MacCallum-Tanner and Horowitz methods and the procedure proposed by Dollimore et al. The values of the activation energy, E a, and the pre-exponential factor, A, of the thermal decompositions were calculated.

Thermal study of areneruthenium(II) derivatives

Abstract The TG and DTG study of areneruthenium(II) derivatives [Ru(arene)Cl 2 L ] (arene = benzene or p -cymene ( p -MeC 6 H 4 CHMe 2 ); L = aniline, diethylamine, dimethylsulfoxide, tetrahydrothiofene or dimethylsulfide) was carried out under a dynamic air atmosphere. The kinetics of the first step of thermal decomposition were evaluated from the dynamic weight loss data by means of Coats-Redfern, MacCallum-Tanner and Horowitz-Metzger methods. The D n and R n models were selected as the models best fitting the experimental TG curves. The values of activation energy, E , and frequency factor, A , of the thermal decomposition were calculated.

Thermal decomposition behaviour of some trivalent transition and inner-transition metal complexes of triethanolamine

Abstract Thermal decompositions of triethanolamine complexes of Cr(III), Fe(III), Ru(III), Rh(III), La(III), Ce(III) and Nd(III) in dynamic nitrogen and air atmosphere were studied by DTA, TG and DTG. The final solid decomposition products were identified by X-ray powder diffractometry. The thermal stability of the complexes in the solid state was discussed. These complexes exhibit a considerable thermal stability and the stability order was found to be: Nd(III) > La(III) ≅ Ce(III) > Cr(III) > Fe(III) > Ru(III) > Rh(III).

Thermal decomposition of ammonium vanadyl oxalate supported on various oxides

The thermal decomposition of ammonium vanadyl oxalate supported on La 2 O 3 , MgO, SiO 2 , Al 2 O 3 , ZrO 2 , TiO 2 , SAPO-5, and ZSM-5 oxides in a dynamic atmosphere of dry air was compared by thermal gravimetric analysis (TG) and differential thermal analysis (DTA). The calcined catalysts were characterized by X-ray diffractometry (XRD). The TG and DTA results demonstrate that the surface acid-base properties of the oxides play a significant role in the decomposition behaviour of the supported ammonium vanadyl oxalate, i.e. the basic oxides exhibit an endothermic effect and the acidic oxides show an exothermic effect. Two mechanisms are suggested for thermal decomposition of ammonium vanadyl oxalate on basic and acidic oxides, respectively. After transformation of the ammonium vanadyl oxalate to vanadia, subsequent rearrangement of the vanadia on the surface of the supports was also observed. During the thermal treatment or calcination in air, solid state reactions of vanadia with the surface of oxides such as La 2 O 3 , ZrO 2 and TiO 2 took place to form new phases.

Thermal decomposition of ammonium vanadyl oxalate supported on various oxides

The thermal decomposition of ammonium vanadyl oxalate supported on La 2O 3, MgO, SiO 2, Al 2O 3, ZrO 2, TiO 2, SAPO-5, and ZSM-5 oxides in a dynamic atmosphere of dry air was compared by thermal gravimetric analysis (TG) and differential thermal analysis (DTA). The calcined catalysts were characterized by X-ray diffractometry (XRD). The TG and DTA results demonstrate that the surface acid-base properties of the oxides play a significant role in the decomposition behaviour of the supported ammonium vanadyl oxalate, i.e. the basic oxides exhibit an endothermic effect and the acidic oxides show an exothermic effect. Two mechanisms are suggested for thermal decomposition of ammonium vanadyl oxalate on basic and acidic oxides, respectively. After transformation of the ammonium vanadyl oxalate to vanadia, subsequent rearrangement of the vanadia on the surface of the supports was also observed. During the thermal treatment or calcination in air, solid state reactions of vanadia with the surface of oxides such as La 2O 3, ZrO 2 and TiO 2 took place to form new phases.

Thermoanalytical investigations of decomposition course of copper oxysalts

The thermal decomposition of basic copper carbonate (malachite; CuCO 3 .Cu(OH) 2 ) in a dynamic atmosphere of air or nitrogen was studied via TG, DTA and DEC at different heating rates. The non-isothermal kinetic and thermodynamic parameters were estimated. The decomposition course was thoroughly followed by examining the structural and morphological consequences of calcining the material at elevated temperatures by IR, XRD and SEM. The results obtained showed that in air CuCO 3 .Cu(OH) 2 released 0.5 H 2 O at 195 o C, transforming into the azurite structure 2CuCO 3 .Cu(OH) 2

Thermoanalytical and pyrolysis—MS studies on dioxouranium(VI) complexes of sodium 1,2-naphthoquinone-1-monoxime-7-sulfonate

A solid dioxouranium(VI) complex of sodium 1,2-naphthoquinone-1-monoxime-7-sulfonate (HL) has been synthesized and characterized. According to elemental analysis its metal to ligand molar ratio was 3. The analysis of potentiometric data obtained from a simulated synthesis by the miniquad program showed that the main component of synthetic product was (UO 2) 3(OH) 4L although the species (UO 2) 3(OH) 5L made up about one fifth of the product. TG, DTG and DSC techniques have been used at 39–900°C to analyze the thermal decomposition of the synthetic product in dynamic air and nitrogen atmosphere. The gaseous decomposition products were identified at 50–400°C by the pyrolysis—MS technique. Some weakly bonded water was eliminated before 90°C; the product also contained 4.8 moles coordinated water which was released at 90–260°C. The decomposition proceeded at 260–800°C in several, partially simultaneous processes, releasing CO 2 together with some minor species. The residues, containing mostly U 3O 8, were 75.1% and 78.7% of the dry mass of the sample in dynamic air and nitrogen atmosphere, respectively. The theoretical amount of U 3O 8, is 72.0%.

Non-isothermal decomposition of silver maleate dihydrate and anhydrous silver fumarate

The non-isothermal decompositions of silver maleate dihydrate (C4HzO4Ag2.2H20) and anhydrous silver fumarate (C4H204Ag2) were studied up to 500~ in a dynamic atmosphere of air, by means of TG and DTA measurements. Both compounds showed some sublimation (at 120~ for silver maleate and at 180~ for silver fumarate) prior to the onset of decomposition (at 170~ for silver maleate and at 280~ for silver fumarate). The gaseous decomposition products of both compounds were found, using IR spectroscopy, to be dominated by maleic anhydride and CO2. Minor proportions of ethylene, ethyl alcohol, acetone, methane and isobutene were also identified. Metallic silver was the final solid product, as identified by X-ray diffractometry. NMR analysis was used to monitor the isomerization of the maleate radical into the more stable fumarate above 230~ Kinetic ~arameters (Ea and In A) were calculated from the effect of heating rate (2, 5, 10, and 20 deg-min- ) on the DTA measurements. A mechanism is suggested for the decomposition pathways of these compounds, on basis of the results obtained and, also, on similarities with analogous systems.

Thermal decomposition of α-tetralyl hydroperoxide under non-isothermal conditions, without solvents

The thermal decomposition of α-tetralyl hydroperoxide (THPO) has been investigated under a variety of conditions: in dynamic (argon and air) atmosphere, static air and self-generated atmosphere by employing DTA and TGA methods. The decomposition of THPO proceeds in two-stages during its thermochemical degradation under nonisothermal conditions in the temperature interval from room temperature to 500°C. It has been shown that the formation of associates resulting from the proton donor-acceptor interactions affects the initial temperature of hydroperoxide decomposition. Free-radical-induced decomposition proceeds in self-generated atmosphere at 165°C. 2,6-Di- tert-butyl-4-methyl phenol at some concentrations and phenyl-α-naphthylamine inhibit the induced radical decomposition. The products from the THPO decomposition are identical with those obtained during its decomposition in various solvents. The DTA and TGA methods show promise as useful techniques for the investigation of free-radical induced decomposition of hydroperoxides.

Spectroscopic and microscopic investigations of the thermal decomposition course of nickel oxysalts: Part 3. Nickel oxalate dihydrate

The non-isothermal decomposition of nickel oxalate dihydrate (NiODH) in dynamic atmospheres of air or nitrogen has been investigated by means of TGA, DTA and DSC. The decomposition was followed by examining the decomposition products in each thermal reaction by IR spectroscopy, X-ray diffraction and electron microscopy. The dehydration reaction was endothermic in both atmospheres, giving rise to anhydrous nickel oxalate which still retained some water. On the other hand, the decomposition process was endothermic in air and exothermic in nitrogen. The final decomposition product in air was NiO, whereas in nitrogen the final product was found to be metallic nickel. Morphological changes throughout the decomposition were followed by SEM observations.

Spectroscopic and microscopic investigations of the thermal decomposition of nickel oxysalts: Part 2. Nickel nitrate hexahydrate

The thermal decomposition of nickel nitrate hexahydrate (NiNHH) under dynamic atmosphere of air has been thoroughly studied. Reactions occurring throughout the decomposition up to 600°C were monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA). These reactions were characterized by analysis of the solid calcination products at different temperatures at which various intermediates were expected. Solid analysis was carried out using infrared spectroscopy and X-ray diffractometry. Non-isothermal kinetic parameters (Δ E, A and k) were determined. TG and DTA under nitrogen atmosphere has been carried out. The results indicate the formation of Ni(NO 3) 2 · nH 2O (where n = 5.5, 4 and 2) and mixture of anhydrous and basic nickel nitrate as intermediate solid products. Basic nickel nitrate intermediate was formed in nitrogen atmosphere as well as in air, which was attributed to a hydrolysis process involving the water of dihydrate intermediate. The morphological changes throughout the decomposition course have been followed by scanning electron microscopy and the results are correlated with the obtained thermoanalytical results of the decomposition course of NiNHH.

Spectroscopic and microscopic investigations of the thermal decomposition of nickel oxysalts: Part 1. Tetrahydroxy nickel carbonate

A study of the thermal decomposition of tetrahydroxy nickel carbonate NiCO 3 · 2Ni(OH) 2 · 4H 2O, was performed by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC) under non-isothermal conditions in dynamic atmospheres of dry air or nitrogen, at different heating rates. Non-isothermal kinetic and thermodynamic parameters were calculated from the effect of heating rates on the maximum temperature of TG and DTA peaks, as well as from the recorded DSC data, using the Ozawa method. The parent material, the intermediates and the final product were characterized by means of infrared spectroscopy and X-ray diffractometry (XRD). The decomposition of tetrahydroxy nickel carbonate commenced through two steps (dehydration and decomposition). The dehydrated intermediate from the first step was found to contain an XRD detectable NiOOH phase. The morphological changes throughout the decomposition course were examined by scanning electron microscopy (SEM) and found to be in accord with the thermal analysis. A reaction pathway is proposed.

Synthesis, characterization, properties and thermal study of lanthanoid isothiocyanate complexes with 2,6-lutidine- N-oxide (2,6-LNO)

Lanthanoid isothiocyanate complexes of general formula Ln(NCS) 3(2,6-LNO) 3(H 2O) n , where n is 3, for Ln is La, n is 1, for Ln is Ce-Nd and Eu-Tb, and n is 0 for Ln is Tm, Lu, Y, were synthesized and characterized. They behave as non-electrolytes in acetonitrile. The anion is bonded through the nitrogen and 2,6-LNO through the oxygen. The nephelauxetic parameter, covalent factor and Sinha's parameter and also the oscillator strength in acetonitrile solution were calculated from the neodymium absorption spectra. A C 3v symmetry and a monocaped trigonal prismatic geometry, with the water molecule located on the rotation axis, was deduced from the emission spectrum of the europium compound. The similarities between the emission spectra of the europium complex and the europium-doped lanthanum and lutetium adducts suggests that the central ions are also involved in a C 3v symmetry. The TG, DTG and DSC measurement were recorded in dynamic air and nitrogen atmospheres and interpreted.

A thermal study of lanthanoid trifluoromethanesulfonate complexes with diphenylphosphinamide (DPPA)

Complexes of composition Ln(F 3C-SO 3) 3 · 5DPPA (where Ln is La, Ce, Nd-Lu, Y) were investigated by TG analysis, IR spectroscopy and visible emission spectroscopy of one of the decomposition products. When heated in dynamic air atmosphere the compounds initially lose some of the DPPA molecules and then the products decompose giving a mixture of carbon, lanthanoid phosphate and lanthanide-oxo-trifluoromethanesulfonate.

Thermal and spectroscopic study of several dithiocarbamates

The thermal decomposition of several dithiocarbamates has been studied by TG and DTG techniques in a dynamic atmosphere of air. Various structures are proposed for the solid compounds, and the decomposition processes have been followed by IR spectroscopy as an approach to the establishment of possible thermal breakdown pathways.

Application of thermal analysis in solid industrial wastes treatment

The choice of an appropriate and safe disposal alternative should be based on the wide range of physicochemical examination thermal analysis in conjunction with other data enables identification of wastes, allows determination of weight losses at any stage of thermal decomposition and characterization of the combustible properties of wastes.In this paper the physicochemical composition of some industrial wastes, which create serious hazards to the natural environment is presented.The following waste materials were investigated: tar wastes from several departments of the coking plant paint-shop wastes from a metallurgical factory. Thermoanalytic measurements were carried out in the dynamic atmosphere of air. Enthalpic values were calculated from the peak areas of the DTA curves.Thermoanalytic data were compared with calorimetric results obtained from an oxygen bomb.The disposal methods for above-mentioned wastes are proposed.

A study of the thermal decomposition of cobalt(II) and nickel(II) oxalate dihydrate using direct current electrical conductivity measurements

The feasibility of using direct current electrical conductivity measurements to study the solid state reactions involved in the preparation of cobalt oxide and nickel oxide from cobalt(H) and nickel(II) oxalate dihydrate have been analysed. Investigations were carried out using atmospheres of static air, dynamic air and dry nitrogen. The study of the isothermal decomposition of cobalt(II) and nickel(II) oxalate dihydrate at different temperatures in these three atmospheres revealed that the anhydrous complexes are formed first. In static air and dynamic air atmospheres, the cobalt oxalate then undergoes oxidation decomposition to Co 3O 4 with the probable intermediate formation of CoO along with the anhydrous complex. In dry nitrogen also, the formation of CoO is well characterized. For nickel(II) oxalate dihydrate, the final decomposition product in all three atmospheres was found to be NiO. The conductivity measurements were supplemented with data obtained by chemical, thermal (TGA and DTA), IR spectroscopic and X-ray powder diffraction analyses. The gaseous decomposition products were characterized by gas-liquid chromatography.