Chrysotile dehydroxylation reaction kinetic model fitting based on isothermal and non-isothermal thermogravimetry data

Abstract This study investigates the kinetics of the dehydroxylation reaction of chrysotile asbestos, a process crucial for the thermal neutralisation and potential reuse of asbestos-containing waste. Chrysotile, historically the most widely used form of asbestos, a structural transformation upon heating, destroying its fibrous, hazardous form. The reaction was analysed using both non-isothermal thermogravimetry (from 2.5 to 22.5 K·min⁻ 1 ) and isothermal calcination (from 823 to 973 K). Activation energy (E a ) was determined using the Friedman isoconversional method and Arrhenius analysis, yielding values of 303 kJ mol⁻ 1 and 188 kJ mol⁻ 1 , respectively. Despite the variation in E a due to methodological and experimental differences, both approaches identified diffusion-controlled mechanisms as the rate-limiting step, particularly the diffusion of water vapour from the reaction zone, but only below approximately 900 K. At higher temperatures, the reaction appears to transition to a different kinetic regime. These findings deepen understanding of the reaction kinetics and contribute to the development of effective thermal treatment technologies for managing asbestos waste.