Thermal decomposition of zinc carbonate hydroxide

This study is devoted to the thermal decomposition of two zinc carbonate hydroxide samples up to 400 deg. C. Thermogravimetric analysis (TGA), boat experiments and differential scanning calorimetry (DSC) measurements were used to follow the decomposition reactions. The initial samples and the solid decomposition products were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and laser particle size analyzer. Results showed that zinc carbonate hydroxide decomposition started at about 150 deg. C and the rate of decomposition became significant at temperatures higher than 200 deg. C. The apparent activation energies (Ea) in the temperature range 150-240 deg. C for these two samples were 132 and 153 kJ/mol. The XRD analyses of the intermediately decomposed samples and the DSC results up to 400 deg. C suggested a single-step decomposition of zinc carbonate hydroxide to zinc oxide with not much change in their overall morphologies