DTA analysis of the system carrier-CuCl2, KCl Part II

Catalysts of the type carrier-CuCl₂, KCl differing in the temperature at which they were obtained and after the ethene oxychlorination process were analyzed thermogravimetrically. Catalysts after the oxychlorination process differed in total salt content and in the molar ratio of CuCl₂ to KCl. A number of endothermic processes were observed in the DTA curves, the extents of these varying with change in the temperature at which the catalysts were obtained and in the catalyst composition.

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Zusammenfassung Bei verschiedenen Temperaturen hergestellte Katalysatoren des Types Carrier-CuCl₂,KCl wurden nach dem Ethylen-Oxychlorierungsprozeß thermogravimetrisch untersucht. Die Katalysatoren unterschieden sich nach dem Oxychlorierungsprozeß sowohl in ihrem absoluten Salzgehalt als auch im Molverhältnis CuCl₂ zu KCl. Anhand der DTA-Kurven wurde eine Anzahl endothermer Vorgänge beobachtet, deren Ausmaß von der Katalysatorenzusammensetzung sowie davon abhängt, bei welcher Temperatur der Katalysator hergestellt wurde.

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The author thanks Prof. dr hab. Zdzislaw Czarny for discussions and advice.     

DTA analysis of water emanation from the system CuCl2 - KCl

Mixtures of CuCl₂ and KCl in molar ratios of Cu to K of 0.5 to 2.0 were obtained at room temperature, and then subjected to DTA analysis in the temperature range 293–473 K. A number of endothermic effects were observed, the extents of these depending on the molar ratio of Cu to K in the mixture.

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Zusammenfassung Bei Zimmertemperatur wurden Gemische aus CuCl₂ und KC1 mit einem Cu:K Molverhältnis zwischen 0.5 und 2.0 erhalten und dann im Temperaturbereich 293–473 K einer DTA-Analyse unterzogen. Es konnte eine Anzahl von endothermen Effekten beobachtet werden, deren Größe eine Funktion des Cu:K Molverhältnisses im Gemisch ist.

     

DTA investigation of thermal dissociation of the solid system CuCl2−KCl

Solid mixtures of CuCl₂ and KCl were annealed at 473 K for different times, then cooled down to room temperature and thermogravimetrically analysed. The differences in the DTA pictures of the samples were analysed. Conclusions were drawn as concerns the solid and liquid states of the mixtures.     

DTA analysis of the system CuCl2-KCl

Mixtures of CuCl₂ and KCl in molar ratios of Cu to K of from 0.5 to 1.0 were heated at 473 K in an air atmosphere, and then subjected to DTA analysis in the temperature range 293–773 K. A number of endothermic processes were observed, the extents of these depending on the molar ratio of Cu to K in the mixture.

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Zusammenfassung DTA-Untersuchungen haben ergeben, daß in Mischungen von CuCl₂ und KCl mit molaren Cu/K-Verhältnissen von 0,5–1,0 nach Erhitzen in Luft bei 473 K im Temperaturbereich von 293 bis 773 K eine Reihe von endothermen Prozessen verlaufen. Das Ausmaß dieser Prozesse hängt vom Cu/K-Verhältnis der Gemische ab.

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Thermogravimetric analysis of the way of water release from the CuCl2−KCl system

Mixtures of CuCl₂ and KCl with molar ratios of Cu to K from 0.5 to 1.0 were heated at 393 K and then they absorbed water from the surroundings at room temperature. DTA, TG and DTG curves were analyzed for the mixtures with absorbed water in the temperature range between 293 and 473 K. The mechanism of the phase changes and water release from the mixtures in the temperature range from 293 to 473 K is proposed.     

Simultaneous TG,DTG, DTA and EGA examination of argillaceous rocks. Part I

The suggested new measuring technique is based on the fact that in the course of the decomposition of clays only three gaseous decomposition products, i.e. SO₃ (SO₂), CO₂ and H₂O are being formed. By thermogastitrimetry the liberation process of the two former products is traced, while by means of a water detector the water released is determined in a selective way. Thus the overlapping processes can be separated. Interpretation and evaluation of the curves can be further improved by performing the examinations in N₂ and O₂ atmospheres respectively, which offers a possibility to conduct the reactions into another direction.

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Zusammenfassung Das empfohlene neue Meßverfahren basiert auf der Tatsache, daß im Verlauf der Zersetzung von Tonerde nur drei verschiedene gasförmige Produkte gebildet Werden: SO₃ (SO₂), CO₂ und H₂O. Der Prozeß der Freisetzung der beiden ersteren Produkte wird durch Thermogastitrimetrie verfolgt, das freigesetzte Wasser wird selektiv über einen Wasserdetektor bestimmt. Die einander überlagerten Prozesse können somit separat betrachtet werden. Interpretation und Ausweitung der Kurven können weiter verbessert werden, indem die Untersuchung auch in Stickstoff- und Sauerstoffatmosphäre durchgeführt wird, was die Möglichkeit darbietet, den Verlauf der Reaktion in eine andere Richtung zu leiten.

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Modelling of quantitative DTA equipment I. Electric analog approach

For an electric model, relationships have been established as a function of the DTA baseline shift, the intensity of the signal, the slope of the leading edge, the heating rate, the thermal resistance of the heating disc built into the DTA apparatus, the contact resistance between the disc and the sample holders, and the heat resistance between the two measuring sites. Some of the relationships obtained supported knowledge acquired earlier by other approaches, and some furnished new information. The limits of use of this simple model are indicated.

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Zusammenfassung Unter Anwendung eines elektrischen Modells wurden Zusammenhänge als Funktion der Verschiebung der Basislinie der DTA, der Signalintensität, der Steile der Leitkante, der Aufheizgeschwindigkeit, des Wärmewiderstandes der in das DTA-Gerät eingebauten Heizscheibe, des Kontaktwiderstandes, zwischen Scheibe und Probenbehälter und des Wärmewiderstandes zwischen den beiden Meßstellen ermittelt. Ein Teil der erhaltenen Zusammenhänge bestätigte von anderen Annäherungen her bereits vorliegende Kenntnisse, ein anderer Teil lieferte neue Informationen. Auf die Grenzen und der Nutzen dieses einfachen Modells wurden hingewiesen.

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Résumé A l'aide d'un modèle électrique, on a établi des relations décrivant l'influence de la dérive de la ligne de base ATD, de l'intensité du signal, de la pente du bord du pic, de la vitesse de chauffage, de la résistance thermique du disque de chauffage incorporé dans l'appareil ATD, de la résistance de contact entre le disque et les porte-échantillons et enfin, de la résistance thermique entre les deux points de mesure. Une partie des relations obtenues confirme les connaissances déjà acquises par d'autres approches, l'autre partie fournit des renseignements nouveaux. Les limites d'utilisation de ce modèle simple sont indiquées.

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Comparative study of the polymorphic species of strontium and calcium formates. I. Differential thermal analysis (DTA)

The existence of new polymorphic varieties of strontium formate (β, δ) and calcium formate (γ, δ) has been established by differential thermal analysis. In our experimental conditions the following species are detected: β-Sr(HCOO)₂ below 235°C; δ-Sr(HCOO)₂ above 235°C; γ-Ca(HCOO)₂ between 150 and 300°C; and δ-Ca(HCOO)₂ beyond 300°C. It is shown that some of the corresponding polymorphic transitions for these formates are possible only in the presence of water traces.     

Study of the binary CaCO3-SiO2 system by quantatitative DTA

Solid-state reactions in the CaCO₃-SiO₂ system with different mass ratios (CaCO₃:SiO₂=from 10.2 to 110) were studied by means of thermogravimetry, quantitative DTA and high-temperature X-ray diffraction up to 1500 °C.It was found that not CaCO₃, but CaO reacted with SiO₂. The rate of decarboxylation increased and the temperature of formation of silicate phases decreased significantly with increasing silica content. Only mono- and dicalcium silicates could be detected as solid-state reaction products. Above 1400 °C, an intensive melting process took place; the amount of silica had no clear effect on its temperature range.Quantitative DTA and X-ray diffraction data proved that, below 1000 °C, not only the decarboxylation process, but also silicate formation must be taken into consideration.     

Reproducibility of phase changes in the system CuCl2−KCl

The reproducibility of the phase changes at 533–543, 573–593K and 603–623 K in the system CuCl₂?KCl was investigated by DTA analysis, supplemented with röntgenographic analysis. Conclusions were drawn in connection with a liquid melt and the solid state of the system.     

A systematic scheme of qualitative analysis for anions. part I

A new and comprehensive scheme for the systematic detection of anions has been put forward. This scheme is based on the precipitation of difficultly soluble salts of anions in groups by basic group reagents in sodium carbonate solution and the subsequent analysis of cach group precipitate or filtrate for the detection of individual members of the group     

Thermal analysis of conducting polymers part I

Thermogravimetry (TG) has been conducted on a series of electroconducting acid-doped polyanilines. The weight loss results suggest that the majority of dopants are eliminated between 230 °C to 350 °C leaving behind the skeletal non-conducting polyaniline. The doped polyaniline are thermally more stable than the pristine polyaniline in air at high temperatures. This suggests that despite the early elimination observed, the presence of dopant at the begining has a stabilizing effect on the skeletal polyaniline. By comparison the acid-doped polyanilines are more thermally stable than many other electroconductive polymers, such as polypyrroles and polyacetylenes.

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Zusammenfassung An einer Reihe von elektrisch leitenden säureversetzten Polyanilinen wurden thermogravimetrische (TG) Untersuchungen durchgeführt. Die Gewichtsverluste zeigen, daß die Mehrzahl der Zusätze bei einer Temperatur zwischen 230 °C und 350 °C eliminiert werden, wobei die nichtleitenden Polyaniline zurückbleiben. Bei hohen Temperaturen ist das versetzte Polyanilin in Luft thermisch stabiler als das ursprüngliche Polyanilin. Das bedeutet, daß eine anfängliche Gegenwart der Zusätze ungeachtet der frühen Eliminierung einen stabilisierenden Effekt auf das Polyanilingerüst ausübt. Im Vergleich erwiesen sich säureversetzte Polyaniline als thermisch stabiler als andere elektrisch leitende Polymere wie z. B. Polypyrrole oder Polyazethylene.

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Some aspects of the phase changes of the CuCl2−KCl system

The mixtures of CuCl₂ and KC1 with Cu to K molar ratios from 0.2 to 2.0 were analysed by thermogravimetry in air and argon atmosphere under different conditions. The samples differed in the temperature of their preparation. Conclusions were drawn concerning the phase changes and the constitution of the CuCl₂?KC1 system.     

Dielectric-differential thermal analysis part I: Method

A thermal analyzer design is described. The instrument is capable of performing simultaneously differential thermal analysis and dielectric thermal analysis under the same experimental conditions. The theoretical basis of dielectric thermal analysis is superficially analyzed, and results obtained on different kinds of substances are presented.

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Zusammenfassung Es wird eine Thermoanalyzer-Konstruktion beschrieben. Mit dem Gerät können differentialthermoanalytische und unter den Bedingungen der thermischen Analyse vorgenommene dielektrische Messungen simultan unter gleichen Bedingungen ausgeführt werden. Die theoretische Grundlage der dielektrischen Thermoanalyse wird kurz behandelt. Für Substanzen verschiedener Art erhaltene Ergebnisse sind angegeben.

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A differential thermal analysis study of some organic acids. part I

The differential thermal analysis curves of 25 organic acids are presented. The acids thermally decomposed to give a series of endothermic peaks which were caused by such reactions as dehydration, decarboxylation, sublimation, decomposition, and phase transitions from the solid to the liquid state. An attempt has been made to provide information which can be employed to identify the acids by a single instrumental technique.     

The DTA analysis of amorphous Co-Fe-Si-B alloys

The compositional dependence of the DTA curves was analyzed for Fe_xCo78–_xSi₉B₁₃ metallic glasses. The crystallization temperature were determined. The results suggest that the thermal stability rises with increasing iron content.

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Zusammenfassung An metallischen GlÄsern FexCo78–xSi9B13 wurde die AbhÄngigkeit der DTA-Kurven von der Zusammenfassung untersucht. Den Ergebnissen nach steigt die thermische StabilitÄt mit wachsendem Eisengehalt.

     

Tutorial on estimating the limit of detection using LC-MS analysis,part I: Theoretical review

A large body of literature exists on the limit of detection (LOD), but there is still a lot of confusion about this important validation parameter. This confusion mainly stems from its statistically complex background. The goal of this two-part tutorial is to discuss and clarify the topic of LOD for practitioners. The two main conclusions of this tutorial are: (1) the choice of how to estimate LOD should be based on the purpose of the analytical method that is being validated (e.g. considerable effort should not be made to estimate LOD for a method that is not used for detecting traces in the vicinity of LOD), and (2) LOD estimates are strongly dependent on different assumptions and the approach used, and therefore caution must be exercised when using the estimate or when comparing different estimates.