Thermal stability of potassium supersulphate and sodium supersulphate

The thermal decomposition of sodium supersulphate (SS) and potassium supersulphate (PS) was investigated with accelerating rate calorimeter. The curves of thermal decomposition temperature and pressure versus time for the two systems were obtained. The kinetic parameters such as apparent activation energy and pre-exponential factor of the thermal decomposition of PS and SS were calculated by the rate constant method. The test decomposition characteristics were modified in adiabatic conditions by the thermal inertia factor. The results showed that the initial exothermic temperature of SS was 156.38°C, the maximum exothermic temperature was 293.01°C, maximum self-heatup rate was 1451.88°C · min^-1, the time to maximum self-heatup rate was 358.13 min and the apparent activation energy was 227.11 kJ · mol^-1, but the initial exothermic temperature of PS was 139.07°C, the maximum exothermic temperature was 289.74°C, maximum self-heatup rate was 202.57°C · min^-1, the time to maximum self-heatup rate was 386.92 min and the apparent activation energy was 170.68 kJ · mol^-1. It can be seen from the results that PS is much easier to decompose, but the reaction of SS is more drastic.