SYNTHESIS, CHARACTERIZATION AND THERMAL-DECOMPOSITION OF DOUBLE SULFATES OF TRIVALENT AL AND FE WITH DIETHANOLAMMONIUM OR TRIETHANOLAMMONIUM MONOVALENT CATIONS

By evaporation of an aqueous mixture of M(III) sulfate and diethanolam monium sulfate or triethanolammonium sulfate in the presence of sulfur ic acid, double sulfates of Al(III) and Fe(III) were obtained. The sto ichiometries of the compounds obtained were determined by means of ele mental and TG analyses. It was found that they have the following gene ral formulae: Al(HOCH2CH2)(2)NH2(SO4)(2) . 6H(2)O; Al(HOCH2CH2)(3)NH(S O4)(2) . 6H(2)O; Fe(HOCH2CH2)(2) NH2(SO4)(2) . 4H(2)O; Fe(HOCH2CH2)(3) NH(SO4)(2) . 6H(2)O. From the X-ray powder diffraction patterns, it wa s concluded that the investigated compounds have different crystal str uctures. It was also established, from the TG curves, that they lose w ater at low temperature and also that the anhydrous double salts decom pose at low temperature (at about 523 K).