KAl(SO4)2 thermal decomposition kinetics modeling through graphical and PSO methods

Abstract

The present manuscript proposes the use of two different approaches for kinetic modeling to study the thermal decomposition of sulfates: a graphical one (sigmoid) and a stochastic one (particle swarm optimization - PSO). Three scenarios were analyzed: pure potassium alum, pure aluminum sulfate, and a mixture of potassium sulfate and aluminum sulfate using TGA under inert atmosphere (N2). The presence of potassium sulfate reduced the decomposition temperature of aluminum sulfate. The results of both methods agree with each other, despite not yielding the same values. The determined apparent orders were around 1.7 for all cases in the graphical method and varied from 1.02 (pure aluminum sulfate) and around 1.5 (potassium alum and mixture of sulfates) for the PSO method. The activation energies were in the range 209–264 kJ mol−1 for the graphical method and 296–352 kJ mol−1 for the PSO method, with the mixture of sulfates having the lowest activation energy values, and the pure aluminum sulfate having the highest ones.