Kinetics aspects of zinc basic carbonate decomposition

The thermal decomposition studies of two zinc basic carbonate samples were carried out up to 400 degreesC by thermogravimetric analysis, boat experiments and differential scanning calorimetry measurements 'DSC'. The initial samples and the solid decomposition products were analyzed by scanning electron microscopy, x-ray diffraction and laser particle size analyzer. The thermal decomposition of both samples started at about 150 degreesC and the rate of decomposition became significant at temperatures higher than 200 degreesC. The apparent activation energies 'Ea' in the temperature range 150-240 degreesC for sample decomposition were between 132 and 153 kJ/mole depending on the sample origin. The XRD analyses of the intermediately decomposed samples and the DSC results up to 400 degreesC suggest that the decomposition reaction probably occur in a single step.