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Abstract  

A simple device suitable for continuous monitoring of carbon dioxide evolved during thermal decomposition reactions is described. Carbon dioxide is transported by a carrier gas through the device connected to thermoanalytical equipment and absorbed by soda lime reagent. The reaction heat released is linearly proportional to the amount of carbon dioxide absorbed.

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A new detector was used for the continuous and selective detection of water vapour released during thermoanalytical investigations of soil samples.

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Application of continuous and selective water detector for quantitative measurements

Determination of the water content of anion-exchange resins

Journal of Thermal Analysis and Calorimetry
Authors:
J. Kristóf
and
J. Inczédy

A standard method was developed for investigation of the adsorbed water in ionexchange resins. The previously-dried anion-exchange resins in Cl, SO4 and HSO4 form were investigated by simultaneous TG, DTG and DTA measurements (derivatograph), and the evolved gases were passed through the continuous and selective water detector system developed earlier.

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Simultaneous TG, DTG, DTA measurements along with the continuous and selective monitoring of carbon monoxide, carbon dioxide and water evolved were carried out on K3[M(C2O4)3].3H2O-type transition metal complexes (whereM=Cr, Fe and Co). Based on the comparison of the recorded curves a detailed description of the decomposition mechanism was possible. In the case of the cobalt complex an exothermic process corresponding to modification of electron configuration is superimposed on the endothermic dehydration reaction.

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A device suitable for the continuous detection of carbon monoxide evolved during themal decomposition processes is described. The detector can be connected directly to thermoanalytical equipment of controlled gas atmosphere. Carbon monoxide collected by the carrier gas is passed through the device containing hopcalite catalyst. In the presence of oxygen carbon monoxide is converted to carbon dioxide in the cell and the temperature change caused by the heat of reaction is measured. According to experience, the change of temperature is linearly proportional to the amount of carbon monoxide released.

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NH4Y and NH4LaY-type zeolite catalysts were prepared by cyclic ion-exchange of a synthetic Linde Y-zeolite. The release of ammonia and water were followed by evolved gas analysis (automatic thermogastitrimetric equipment) as well as with a continuous selective water detector.

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The thermal decomposition of [Co(NH3)5CO3]NO3, [Co(NH3)5NO2](NO3)2 and [Co(NH3)5H2O](NO3)3 complexes was studied by simultaneous TG, DTG, DTA (Derivatograph-C), termogastitrimetry, continuous selective water detection, TG-MS, and XRD methods.

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Abstract  

The thermal behaviour of fully and partially expanded kaolinites intercalated with formamide has been investigated in nitrogen atmosphere under quasi-isothermal heating conditions at a constant, pre-set decomposition rate of 0.20 mg min–1 . With this technique it is possible to distinguish between loosely bonded (surface bonded) and strongly bonded (intercalated) formamide. Loosely bonded formamide is liberated in an equilibrium reaction under quasi-isothermal conditions at 118°C, while the strongly bonded (intercalated) portion is lost in an equilibrium, but non-isothermal process between 130 and 200°C. The presence of water in the intercalation solution can influence the amount of adsorbed formamide, but has no effect on the amount of the intercalated reagent. When the kaolinite is fully expanded, the amount of formamide hydrogen bonded to the inner surface of the mineral is 0.25 mol formamide/mol inner surface OH group. While the amount of surface bonded formamide is decreasing with time, no change can be observed in the amount of the intercalated reagent. With this technique the mass loss stages belonging to adsorbed and intercalated formamide can be resolved thereby providing a complex containing only one type of bonded (intercalated) formamide.

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