SYNTHESIS, IDENTIFICATION AND THERMAL-DECOMPOSITION OF DOUBLE SULFATES OF AL(III) AND FE(III) WITH THE ETHANOLAMMONIUM CATION

By evaporation of an aqueous mixture of M(III) sulfate and ethanolammo nium sulfate (a) in the presence of sulfuric acid and (b) without sulf uric acid, double acid, double sulfates of AI(III) and Fe(III) were ob tained. The stoichiometries of the compounds were obtained by means of elemental and TG analyses. From the X-ray powder diffraction patterns it was concluded that, depending on the presence or otherwise of sulf uric acid, two different structures of the Al double sulfate with the same empirical formula HOCH2CH2NH3Al(SO)4)2 . 6H2O were obtained. It w as also established from the TG curve that the HOCH2CH2NH3Fe(SO4)2 . 2 H2O obtained dehydrates at a higher temperature and is more stable tha t the AI(III) double sulfates.