Thermal Stability and Decomposition of Poly[ethylenediaminetetraacetato-Aqua-Disodiumnickel(ii)]: A Tga–dta Investigation

The thermal stability and decomposition behavior of poly[ethylenediaminetetraacetato-aqua-disodium-nickel(II)] were investigated using simultaneous thermogravimetric analysis (TGA) and differential thermal analysis (DTA) in the temperature range of approximately 25-800 °C. The thermogram revealed a multistep decomposition process involving dehydration, partial degradation of coordinated organic fragments, and complete decomposition of the EDTA framework. Three major mass-loss stages were observed. The first decomposition stage occurred between 88.0 and 316.9 °C with a mass loss of 40.82%, corresponding to the removal of coordinated water molecules and the initial degradation of organic functional groups. The second stage, between 316.9 and 439.2 °C, exhibited a mass loss of 29.62%, attributed to the decomposition of the EDTA ligand backbone and cleavage of metal-ligand coordination bonds. The third stage occurred between 441.4 and 753.0 °C with an additional mass loss of 9.97%, corresponding to carbonaceous residue oxidation and formation of thermally stable nickel-containing inorganic residues. The DTA curve displayed thermal events associated with these decomposition processes, confirming the multistep thermal degradation mechanism. The results demonstrate that the complex possesses good thermal stability up to approximately 300 °C and decomposes progressively at higher temperatures.