Kinetic analysis of γ-MnO2 thermal treatment

Kinetic analysis of the thermal processes occurring during water loss for gamma-MnO2 was performed using two techniques, namely, the induction period and iso-conversional methods. The modelling and analysis arising from thermogravimetric studies of the material gave rise to the pre-exponential factor and, most importantly, the activation energy for the transition. Analysis using the induction period showed the activation energy to increase linearly with extent of conversion, ranging from 109-250 kJ mol(-1), while the iso-conversional method gave values in the range 66-76 kJ mol(-1), with higher values for both lower and higher extents of conversion. Comparison of these methods indicates that the iso-conversional method is the preferred technique for determining the kinetic parameters for this process. Overall, this allows for the determination of the optimum heat treatment temperature and time for the gamma-MnO2.