Thermogravimetric method

The residual moisture content, calculated from DR data, measures the amount of water, which can be desorbed at the product temperature. The procedure corresponds therefore to the thermogravimetric method [1.83] with some practical advantages ... 

Thermogravimetric methods such as pyrolysis gas chromatography-mass spectrometry have been used to characterize hydrocarbon sludges from polluted soils [10]. In combination with conventional extraction and supercritical fluid extraction followed by gas chromatography-mass spectrometry, over 100 constituents were identified in soil samples. Thermogravimetric analysis-mass spectrometric results distinguished between the release of a component by thermosorption and by pyrolysis. 

Table 1. Thermogravimetric methods, simultaneous techniques and experimental...

For demonstrating the versatility and general usefulness of thermogravimetric methods, a large number of experiments was carried out in different areas of physical and inorganic chemistry and in various fields of applied research. The results of some of these investigations will be described in what follows. 

These investigations were concerned with the formation of alkaline earth chromates Me2+Cr6+04 during solid state reactions with Cr203. Thermogravimetric methods are especially useful for such studies and allow one to follow the oxidation... 

Tesconi, M. and Yalkowsky, S.H. A novel thermogravimetric method for estimating the saturated vapor pressure of low-volatility compounds, J. Pharm. Sci., 87(12) 1512-1520, 1998. 

Elemental composition (of anhydrous MgS04) Mg 20.20%, S 26.63%, O 53.16%. The water of crystalization may be measured by thermogravimetric methods. Magnesium may be analyzed by AA or ICP-AES following acid digestion. 

Elemental composition Zn 63.24%, F 36.76%. ZnF2 may be characterized from its x-ray and other physical properties. The water of crystaUization in the tetrahydrate may be determined by thermogravimetric method. A small amount of compound is dissolved in water (anhydrous salt is very slightly soluble in water) and analyzed for fluoride ion by the electrode method or by ion chromatography. A diluted acid solution of the compound is analyzed for zinc by various instrumental methods (See Zinc). 

Elemental composition (for anhydrous Zr(N03)4 Zr 26.89%, N 16.51, O 56.59%. The water of crystallization can be measured by thermogravimetric methods. The nitrate ion can be measured by ion-selective electrode or ion chromatography. Zirconium may be analyzed in an aqueous solution by flame... 

The most extensive investigation was carried out by Guiochon and L. Jacqu6 [30] and Guiochon [17, 31]. They used the same thermogravimetric method as in their former experiments, and examined the influence of chromium oxide (0.3-8%), potassium bichromate (0.1-3%), chromium nitrate (1-5%) and also pure chromium (0.033-5.5%) [30]. 

Physicochemical properties of L zeolites and of clinoptilolite were studied by adsorption, chromatographic, spectral, and ther-mogravimetric methods. The sodium form of L zeolite is characterized by better adsorption with respect to water and benzene vapor and by higher retention volumes of C C hydrocarbons and CO than potassium and cesium forms. The activation energy of dehydration determined by the thermogravimetric method decreases on going from the sodium to cesium form of L zeolite. When calcium is replaced by potassium ions in clinoptilolite, the latter shows a decreased adsorption with respect to water vapor. The infrared spectra of the L zeolite at different levels of hydration show the existence of several types of water with different bond characters and arrangements in the lattice. 

Potassium, sodium, and cesium forms of the L zeolite were studied by the thermogravimetric method. There is an endothermal effect on the initial potassium zeolite KL-DTA curve within 50°-300°C caused by the loss of adsorbed water. Most of the water (15.1%) is lost in this narrow... 

Recently, a newer method (Noel, 1984) has also been accepted (ASTM D-4530) that requires smaller sample amounts and was originally developed as a thermogravimetric method. The carbon residue produced by this method is often referred to as the microcarbon residue (MCR). Agreements between the data from the three methods are good, making it possible to interrelate all of the data from carbon residue tests (Long and Speight, 1989). 

Phosphorus is present in zinc dialkyldithiophosphate and deactivate platinum catalysts in engine exhaust systems. Using zinc, antimony and oxothiomolybdate dialkyl-dithiocarbamate (MoDTC) complexes alone or in combination with other lubricating oil additives appears to solve this problem. Antimony complexes are used also as extreme pressure agents while molybdenum ones as friction modifier additives (Hill et al., 1994). Analyses of Zn(dtc)2 decomposition using the thermogravimetric method, flash vacuum pyrolysis, and four-ball machine... 

N-Trialkyl-B-trihaloborazines can be prepared without difficulty from alkylammonium halide or alkylamine and trihaloborane 4> when the resulting alkylammonium tetrahaloborate or alkylamine-trihalo-borane is refluxed in chlorobenzene. Yields are nearly quantitative in most cases. This same observation holds true for N-triaryl-B-trihalo-borazines. Extensive studies using thermogravimetric methods in addition to preparative methods did not provide for the isolation or identification of any intermediates between the amine-trihaloborane and the borazine stage of the reaction 45 4fl>. 

Phosgene proved to be an appropriate reactant to remove aluminium from the zeolite framework [1,2]. Detailed measurements have been carried out to investigate the adsorption of phosgene [3], the mechanism of dealumination by infrared spectroscopic and thermogravimetric methods [4], structural consequences [5], adsorption and catalytic properties of modified mordenites [6]. In addition an NMR study has been carried out, to measure the thermal stability of so-called hydroxy nests in H-mordenite dealuminated with phosgene [7]. 

PCA warming-up in the presence of oxygen or in the air leads to great changes in polymer chemical composition, which is accompanied by the loss of positive service properties of PCA materials. These changes allow to registrate complex thermogravimetric method of analysis. 

Adamczyk, D. and Cyganski, A. (2006) Thermogravimetric method for simultaneous determination of potassium and ammonium involving thermal decomposition of tetraphenylborates. Chemia Analityczna, 51 (2), 241-249. 

The free lime [Ca(OH)2] and carbonate (CaC03) contents of calcium silicate hydrates, ranging from 1.0-20%, were determined by a thermogravimetric method by Biffen (33). The mass-loss curves for a series of calcium silicate hydrates, calcium silicate hydrates plus varying amounts of calcium hydroxide, and calcium silicate hydrates plus varying amounts of calcium carbonate are given in Figure 4.15. 

Good agreement with other accepted methods was reported for the determination of water, free lime, and carbonate in calcium silicate hydrates by the thermogravimetric method. 

If the specific surfaces of the products are plotted against the decomposition temperature (at constant decomposition time), typical curves are obtained [3]. From these, oncecannot only read off the optimum conditions for creation of maximum surface but one can also obtain some indication of the mechanism of the decomposition reaction. Complete explanation of these phase relations (in some cases, an extremely complicated problem) requires the use of x-ray and IR spectroscopy and thermogravimetric methods. 

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