Kinetics and thermodynamics of the formation of MnFeP4O 12

Boonchom, Banjong; Thongkam, Montree

doi:10.1021/je900310m

Kinetics and thermodynamics of the formation of MnFeP4O 12

Author(s)

Boonchom, Banjong

Thongkam, Montree

Date Issued

January 14, 2010

Type

Article

DOI

10.1021/je900310m

Abstract

The kinetics and thermodynamics of dehydration and intermolecular polycondensation reactions of Mn1/2Fe1/2(H 2PO4)2 ·H2O and Mn 1/2Fe1/2(H2PO4)2 were studied under nonisothermal heating by thermogravimetry (TG). On the basis of three calculation procedures and 24 kinetic mechanism functions, kinetic triplets (E, A, kinetic model) using the Arrhenius equation were calculated for both processes. The comparison of the results obtained with these calculation procedures show a strong dependence on the selection of the mechanism function for the process. The thermodynamic functions (ΔH*, Cp, ΔG*, and ΔS*) of both reactions are calculated from differential scanning calorimetry (DSC) experiments. Kinetic and thermodynamic results indicate that the polycondensation step has a lower rate and is a stronger reaction than the dehydration step and corresponds to the breaking of the strong hydrogenbonded P-OH group, in connection with the polycondensation reaction, which confirms that the decomposition product (manganese iron cyclotetraphosphate, MnFeP4O12) was obtained. © 2010 American Chemical Society.

Citation

Journal of Chemical and Engineering Data, 55(1), 211-216, 2010