Thermal decomposition of basic aluminium ammonium sulphate in an environment of carbon and water vapour

Abstract By means of the thermogravimetric method, differential thermal analysis. X-ray diffraction phase analysis, infrared spectroscopy, electron microscopy and chemical analyses, stages of decomposition of basic aluminium ammonium sulphate (BAAS) in an environment of carbon and water vapour were studied. It has been found that the addition of carbon and water vapour influences the course of alunite decomposition only in the last stage, i.e. the desulphuration of the compound. This process occurs at a lower temperature than in air. The final product of decomposition of the basic salt at 1223 K is γ-Al2O3. The experimental work was preceded by the thermodynamic analysis of the desulphuration process of BAAS in an environment of carbon and water vapour, and the results have been correlated with experimental data.