Figure 1:
Reaction progress (TG, normalized signals) of hydromagnesite decomposition as a function of time under differing temperature modes (marked on the curves).
 

Figure 2:
Temperature profiles in isothermal and oscillatory temperature modes (24 h period)
1/ Temperature variations 230°C ± 40°C
2/ Temperature variations 230°C ± 20°C
3/ Isothermal 230°C


Figure 3:
AKTS-Thermokinetics software input.

In Fig. 2, the arithmetic mean temperature (230°C) of the oscillatory temperature modes is the same for all experiments, however, the differences in the amplitudes greatly influence the reaction progress (see Fig. 1). The prediction of the decomposition of hydromagnesite at 230°C with ± 40°C amplitude and 24h period indicates that after one year the sample will be almost fully decomposed. For the same mean temperature (230°C) and period (24h) but different amplitudes (20°C and 0°C for the isothermal conditions), hydromagnesite will decompose much less in this period of time (reaction extents are about 37 and 34%, respectively). Total decomposition for the 20 °C amplitude is reached within about 4 years whereas under isothermal conditions, about 9 years are required.