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  • Author or Editor: X.-G. Meng x
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Abstract  

A novel solid complex, formulated as Ho(PDC)3 (o-phen), has been obtained from the reaction of hydrate holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phenH2O) in absolute ethanol, which was characterized by elemental analysis, TG-DTG and IR spectrum. The enthalpy change of the reaction of complex formation from a solution of the reagents, Δr H m θ (sol), and the molar heat capacity of the complex, c m, were determined as being –19.1610.051 kJ mol–1 and 79.2641.218 J mol–1 K–1 at 298.15 K by using an RD-496 III heat conduction microcalorimeter. The enthalpy change of complex formation from the reaction of the reagents in the solid phase, Δr H m θ(s), was calculated as being (23.9810.339) kJ mol–1 on the basis of an appropriate thermochemical cycle and other auxiliary thermodynamic data. The thermodynamics of reaction of formation of the complex was investigated by the reaction in solution at the temperature range of 292.15–301.15 K. The constant-volume combustion energy of the complex, Δc U, was determined as being –16788.467.74 kJ mol–1 by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δc H m θ, and standard enthalpy of formation, Δf H m θ, were calculated to be –16803.957.74 and –1115.428.94 kJ mol–1, respectively.

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Abstract  

This paper presents a novel data processing method for thermokinetics of faster first-order reaction on the basis of the double-parameter theoretical model of a conduction calorimeter, in which the rate constant of a first-order reaction can be calculated from only four peak height data from the same thermoanalytical curve without using any peak-area. The saponifications of ethyl acetate and methyl acetate in aqueous solution and ethyl benzoate in aqueous alcohol have been studied to test the validity of this method. The rate constants calculated with this method are in fair agreement with those in literature; hence the validity of this method is demonstrated.

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Abstract  

On the basis of the theory of thermokinetics proposed in the literature, a novel thermokinetic method for determination of the reaction rate, the characteristic parameter method, is proposed in this paper. Mathematical models were established to determine the kinetic parameters and rate constants. In order to test the validity of this method, the saponifications of ethyl benzoate, ethyl acetate and ethyl propionate, and the formation of hexamethylenetetramine were studied with this method. The rate constants calculated with this method are in agreement with those in the literature, and the characteristic parameter method is therefore believed to be correct.In the light of the characteristic parameter method, we have developed further two thermo-kinetic methods, the thermoanalytical single and multi-curve methods, which are convenient for simultaneous determination of the reaction order and the rate constant. The reaction orders and rate constants of the saponifications of ethyl acetate and ethyl butyrate and the ring-opening reaction of epichlorohydrin with hydrobromic acid were determined with these methods, and their validity was verified by the experimental results.

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Abstract  

Highly oriented single crystal antimony nanowire arrays have been synthesized within anodic aluminum oxide (AAO) template by pulsed electrodeposition. Thermal behavior and oxidation analysis of the antimony nanowires have been investigated by means of thermogravimetry and differential scanning calorimetry in Ar and air atmosphere, respectively. Compared to bulk antimony, the antimony nanowires exhibit a lower sublimation temperature at 496.4°C. Evident oxidation of the Sb nanowires occurs at 429.8°C in air atmosphere and α-Sb2O4 nanowires have been obtained as the oxidation product. The results indicate that the sublimation and the oxidation of the antimony nanowires in the AAO template is a slow multi-step process. The present results are of relevance when processing antimony nanowries for thermoelectric applications at high temperatures.

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