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  • Author or Editor: G. Thomas x
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A thermo magnetic analysis (TMA) apparatus is used to follow reactions under controlled conditions of temperature and pressure with the Faraday method. Relations giving the conversion degree λχ at a given timet as a function of the sample susceptibility are presented. Methods for studying the effects of the magnetic field on the reaction kinetics are considered. In particular, the kinetic curves obtained for the reaction

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Abstract  

Copper(II), zinc(II) and cadmium(II) complexes of the Schiff base, fluorenone anthranilic acid were prepared and characterized by elemental analysis, magnetic measurements, conductivity experiments and electronic and infrared spectral studies. The thermal decomposition kinetics and mechanism of these chelates was studied from TG data.

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A unique application of forensic neutron activation analysis involving the analysis of trace levels of tungsten, cobalt and tantalum was presented as evidence in a murder trial. The evidence materials analyzed included the blous of the victim, bed sheets, a pair of pantyhose used in strangulation, head and public hair from the suspect, and several samples of raw materials used at a factory where the suspect was employed. The stalned areas of the fabrics analyzed showed trace levels of cobalt, tantalum, and tungsten which were not present in the fabric mattrices. The occupation of the suspect exposed him to fine dust particulates containing these trace elements. Although eyewitness accounts indicated that the suspect was in the neighborhood, there was, however, no evidence other that the neutron activation analysis results to indicate the probable presence of the suspect at the scence of the crime. A jury trial accepting neutron activation analysis findings resulted in a conviction.

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The behaviour of the system PbO-PbSO4 was studied between 400 and 900°. Three basic sulphates could be identified by X-ray diffractometry namely: PbO · ·PbSO4; 2 PbO·PbSO4 and 4 PbO·PbSO4.

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The adsorption of n -butane on extruded cylindrical activated carbon grains is studied providing two kinds of information: the influence of the temperature and the hydrocarbon partial pressure on the adsorption dynamics (kinetic study) and on the adsorption capacities (thermodynamic study). The thermodynamic aspect could be interpreted by a Langmuir model. From a kinetic point of view, we have experimentally proved that strong temperature variations occur inside the particles during the adsorption. In this paper, a kinetic model including both mass and heat transfer phenomena is proposed. Good agreement is found between the kinetic model predictions and the experimental mass and temperature variations inside the grain during the hydrocarbon adsorption.

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The phase diagram of solid-solid equilibria in the system Ca3(PO4)-CaNaPO4 has been studied by thermal analysis. The results are confirmed by X-ray diffraction at different temperatures. This study was limited to that of mixtures in a temperature range determined by previous results. The present work confirms the existence of two metastable diagrams which are superimposed on the stable diagram.

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The kinetics of heterogeneous reactions are in most cases studied by means of integral curves which represent the degree of reaction as a function of the time. Recently, rate vs. time curves have also been used for this purpose. The present paper draws attention to the importance of curves giving the degree of reaction as a function of the rate of reaction; these facilitate the investigation of separate points, make possible the interpretation of various factors, and provide valuable data concerning the mechanism. Three methods are suggested for preparing these curves and the decomposition of sodium hydrogen carbonate is given as an example.

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