EVALUATION OF KINETIC-PARAMETERS FROM A SINGLE TG CURVE BASED ON THE SIMILARITY THEORY AND PROCESS SYMMETRY

The equation for calculation of the activation energy of the diffusion of the evolved products through the matrix (E) from a single TG curve were proposed by solving Fick's laws. The solution is based on the si milarly theory by utilizing a Fourier number. The proposed method was examined by using mass loss data for the dehydroxylation of some micas with and without FeO (muscovite and its varieties and lepidolite) as determined from their TG curves. The E values for the first stage of t he dehydroxylation of these micas are E-1=85+/-10 kJ mol(-1); for the final stage E-2=380+/-40 kJ mol(-1) and for the mass loss connected wi th fluorine E-F=85+/-10 kJ mol(-1).