Thermal behavior of nicotinate of some bivalent transition metal íons in dry CO2 and N2 atmospheres

Synthesis, characterization and thermal decomposition of bivalent transition metal nicotinates M(C6H4NO2)2 . nH2O (M = Mn (II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)), as well as the thermal decomposition of sodium nicotinate, were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC) coupled to infrared spectroscopy (FTIR) and complexometry. In both atmospheres, the thermal decomposition of sodium nicotinate up to 500 oC, occurs with the formation of sodium carbonate and carbonaceous residue and up to 800 oC the mass loss is still being observed. In CO2 atmosphere the thermal decomposition of these compounds occurs in three consecutive steps, with the formation of the respective metal or metal oxides: MnO, FeO, CoO, Ni°, Cu° and ZnO. In N2 atmosphere, the thermal decomposition also occurs, in three consecutive steps and only iron and cobalt compounds, with the formation of Fe3O4 and CoO, respectively, while the other compounds the mass loss is still being observed up to 1000 oC.