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Abstract  

The role that can be played in the elucidation of the limestone sulphation mechanism by thermal analysis methods with some specific procedures is discussed. Contrasting examples of applications of thermoanalytical techniques using the variable conditions are provided. These examples deal with the programmed thermal analysis using different gas sequences, the influence the calcination and sulphation conditions on the capture of SO2, the effect of catalysts on limestone sulphation and the thermal stability of CaSO3. Two proposed mechanisms were supported by the phase identification of the solid products.

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. cerevisiae that encodes a high-affinity sulphate transporter at the plasma membrane. Mol Gen Genetics 247 , 709 (1995). Isolation of cDNA from S. cerevisiae that encodes a high-affinity sulphate transporter at the plasma membrane

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. , Gruncharov , I. and Dombalov , I. , Modern procedures for processing the waste ferro-sulphates , CINTI, No. ND/4155/90, 1990 . 5 Gruncharov , I. , Pelovski , Y. , Nishev , T. and

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Introduction Chromium tris thiourea sulphate (TTCS) is a metal organic nonlinear optical crystal which can be grown fairly and easily in large sizes from aqueous solution. Its growth and characterization have been reported in a

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free ligands themselves. Concerning the above mentioned magnesium ion role and the need of materials of beneficial properties the magnesium sulphate complex compounds with hmta and phen were synthesised and studied, especially, in the matters of their

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Aluminum sulphate hydrates

Kinetics of the thermal decomposition of aluminum sulphate using different calculation methods

Journal of Thermal Analysis and Calorimetry
Authors: H. Moselhy, J. Madarász, G. Pokol, S. Gál, and E. Pungor

Abstract  

Three different calculation methods of deriving kinetic parameters (activation energy and preexponential factor) from dynamic TG data have been applied for the sulphate decomposition stage of the aluminum sulphate octadecahydrate. The constant rate experiments were carried out by Derivatograph and DuPont thermobalances. The three parameters estimation methods included a simple differential method, the classical Coats-Redfern and a new direct integral method. The fits of the curves obtained by these procedures were compared both graphically and numerically. It was found that the direct integral method gave the most satisfactory results. With the order type reaction models this method in each case produced the smallest residual deviation values and the best fitting curves compared to those obtained by the other two methods. The activation parameters calculated by the differential method were not acceptable at all, for the estimated curves were very far from the measured ones.

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Abstract  

The direct production of copper sulphate from copper ore is an important route to recover copper. The condition, however, is dependant on temperature and sulphatising environment. The oxidation of chalcopyrite in static air bed condition has been studied by TG/DTA and DSC techniques. The addition of catalysts, improved the sulphation by in-situ producing better condítions. The mutual effects of sulphides were further confirmed by studying the oxidation reaction on pure copper-iron sulphides and results so obtained were corroborated with X-ray diffractrograms. With only chalcopyrite a mass gain of 8% (TG) corresponding to copper sulphate formation was observed, in the temperature range 628–738 K. The TG plots showed respective mass gain of 14, 17 and 12% in presence of Fe2O3, Na2SO4 and FeSO4 with chalcopyrite in the wider temperature range 628–923 K. As such the cupric sulphide had a negligible tendency of sulphation, which increased with the addition of ferrous sulphide mixture under the temperature range studied. At higher temperature copper ferrite formation was found.

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+ ) by the loss of an electron, which depends on the experimental conditions. Ferrous sulphate (FeSO 4 · x H 2 O, x ≤ 7, divalent iron) and ferric sulphate (Fe 2 (SO 4 ) 3 · x H 2 O, x ≤ 9, trivalent iron) are typical iron salts. They are widely used

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decomposition of two nickel complexes containing ethylenediamine as the ligand viz., tris(ethylenediamine)nickel(II) oxalate dihydrate and tris(ethylenediamine)nickel(II) sulphate in dynamic air and helium. We have detected the evolved gaseous species and

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