Fabrício Rossi Marques Matias, V. C. D. Silva, R. Nunes
Jul 27, 2017
Citations
0
Influential Citations
4
Citations
Journal
Journal of Thermal Analysis and Calorimetry
Abstract
The lanthanide 4-amino-benzenesulfonate salts (or sulfanilates) were obtained by the reaction of lanthanide carbonates (La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+ and Gd3+) and 4-amino-benzenesulfonic (or sulfanilic) acid in aqueous solution. Simultaneous thermogravimetry, differential thermal analysis and differential scanning calorimetry, elemental analysis, X-ray powder diffractometry and infrared spectroscopy (FTIR) were used to characterize and to study the thermal behavior of these compounds. The general formula could be established as LnL3·nH2O, where Ln represents trivalent lanthanide ions (La–Gd), L is the 4-amino-benzenesulfonate anion (NH2C6H4SO3−) and n = 8 (La–Gd) and n = 7 only for Ce. The thermal behavior indicates that dehydration occurs in a single step up to 443 K, characterized by an endothermic peak, and the enthalpy of dehydration was evaluated by DSC. Thermal decomposition takes place above 523 K producing a stable intermediate Ln2O2SO4 characterized by X- ray diffraction, which in the sequence decomposed to the respective oxides. For the La3+, Nd3+ and Pr3+ sulfanilates, the residual oxide formation occurs only after 1573 K.