The effects of heat and mass transport on the results of thermal decomposition studies. Part 1. The three reactions of calcium oxalate monohydrate

Tamas Szekely, Gabor Varhegyi, Ferenc Till, Piroska Szabo, Emma Jakab

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The importance of heat and mass transfer was studied in the case of three simple inorganic reactions (CaC2O4·H2O ⇌ CaC2O4 + H2O, CaC2O4 → CaCO3 + CO and CaCO3 ⇌ CaO + CO2) by thermogravimetry and thermogravimetry-mass spectrometry. A "compensation effect" was observed between the heating rate and the sample mass: the measured thermogravimetric curves did not change when the heating rate was increased and the sample mass was decreased by roughly the same factor in the ranges of 30-200°C/min and 1-8 mg, respectively. This fact reveals a complete lack of kinetic control and casts doubt upon the kinetic calculations based on the shift of the decomposition temperature by the increase in heating rate. Experiments at 4°C/min and 0.5 mg proved that mass transport is also a dominant rate-controlling process for the irreversible second reaction.

Original languageEnglish
Pages (from-to)71-81
Number of pages11
JournalJournal of Analytical and Applied Pyrolysis
Volume11
Issue numberC
DOIs
Publication statusPublished - Oct 1987

Keywords

  • Calcium oxalate
  • heat transfer
  • kinetics, reaction
  • mass spectrometry
  • mass transfer
  • pyrolysis
  • thermogravimetric analysis.

ASJC Scopus subject areas

  • Analytical Chemistry
  • Fuel Technology

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