Reaction kinetics during non-isothermal solid-state synthesis of boron trioxide via boric acid dehydration

Thermal kinetics involved during boric acid ( $${\mathrm{H}}_{3}{\mathrm{BO}}_{3}$$ ) dehydration is investigated through TGA and DTA. It is observed that the dehydration of boric acid occurred in three stages. Firstly, metaboric acid ( $${\mathrm{HBO}}_{2}$$ ) forms at ~ 410 K and converts into tetraboric acid ( $${\mathrm{H}}_{2}{\mathrm{B}}_{4}{\mathrm{O}}_{7}$$ ) with an increase in temperature (~ 450 K). Finally, boron trioxide ( $${\mathrm{B}}_{2}{\mathrm{O}}_{3}$$ ) forms at 800 K after complete dehydration of boric acid. Kinetic triplets are calculated by employing two different approaches i.e. overall and deconvolution. In both approaches, activation energy is determined by following Kissinger–Akahira–Sunsose (KAS) method and reaction mechanism is identified through integral master plots. According to the overall kinetic analysis, reaction mechanism is not the same for complete reaction. However, deconvolution analysis separates the overlapping of reactions involved during boric acid dehydration and kinetic triplets are calculated. Finally, it is observed that deconvolution kinetic analysis is more appropriate for analyzing complex thermal decomposition processes.