A new diagnostic when determining the activation energy by the advanced isoconversional method

The Advanced Isoconversional (AIC) method involves minimization of a function which uses conversion data at a minimum of three heating rates to determine an activation energy (Ea) at different values of conversion (α). Reactions that can be described by a single model give an Ea which is independent of α, while reactions which are described by more than one model give an Ea which varies with α. Shifts in the conversion curves due to error can lead to Ea vs. α trends which falsely indicate, or mask, true multi-model kinetics. It was found that the minimum value obtained during optimization of what we call the 'Optimization Indicator' (Ω) can indicate whether trends in Ea vs. α are likely to be error-derived in the case of single-model reactions or artifacts in the case of multi-model reactions. Ea and Ω for the calcination of CaCO3 are used to demonstrate the experimental application of this new diagnostic.