The effect of particle size on the thermal decomposition kinetics of potassium bromate

The thermal decomposition of potassium bromate (KBrO₃) has been studied as a function of particle size, in the range 53?C150???m, by isothermal thermogravimetry at different temperatures, viz. 668, 673, 678, and 683?K in static air atmosphere. The theoretical and experimental mass loss data are in good agreement for the thermal decomposition of all samples of KBrO₃ at all temperatures studied. The isothermal decomposition of all samples of KBrO₃ was subjected to both model fitting and model-free (isoconversional) kinetic methods of analysis. Isothermal model fitting analysis shows that the thermal decomposition kinetics of all the samples of KBrO₃ studied can be best described by the contracting square equation. Contrary to the expected increase in rate followed by a decrease with decrease in particle size, KBrO₃ shows a regular increase in rate with reduction in particle size, which, we suggest, is an impact of melting of this solid during decomposition.