Revista internacional de contaminación ambiental
versão impressa ISSN 0188-4999
FLORES-ESPINOSA, Rosa María; ORTIZ-OLIVEROS, Huemantzin Balan; BONIFACIO-MARTINEZ, Juan e RIVERO-ESPEJEL, Ignacio. Thermodegradation of used mixed bed ion-exchange resins. Rev. Int. Contam. Ambient [online]. 2011, vol.27, n.3, pp.223-230. ISSN 0188-4999.
In order to select a treatment method for the final disposition of ion-exchange resins used in nuclear power plants, a thermal study of styrene-divinylbenzene resins based on sulfonic and ammonium quaternary groups was carried out to determine their mode of decomposition as well as their relative thermal stability using thermogravimetric analysis (TGA). The Kissinger differential method was used to calculate thermal activation energy. Infrared spectroscopy (IR) was used to characterize the resin degradation steps. The resins undergo thermal degradation from 373 to 770 K through a dehydration (331 K), followed by a chemical decomposition. Anionic resins decompose releasing tertiary amines (453 K and Ea = 104.06 kJmol-1) while cationic resins decompose releasing sulfur compounds (610 K and Ea = 144 kJmol-1). Depolymerization of cationic (667 K and Ea = 270 kJmol-1) and anionic (707 K and Ea = 228.7 kJmol-1) resins was evaluated by IR identification of aliphatic and aromatic compounds. The correlation of these analyses allowed developing the chemical reactions of thermal decomposition of resins.
Palavras-chave : radioactive waste; TGA; resin degradation; used ion-exchange resins.