Radiolytic and Thermal Dehalogenation of CFC-113 Adsorbed on Molecular Sieve 13X

Abstract

Abstract The reductive dehalogenation of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) has been radiolytically and thermally initiated on molecular sieve 13X. The molecular sieve adsorbing CFC-113 was irradiated with γ-rays or heated, and was then soaked in water. The Cl− and F− concentrations and the pH of the supernatant solutions were measured to follow the dehalogenation reaction. These values for samples irradiated at a dose rate of 7.8 kGy h−1 and heated at 150 °C were almost the same when the irradiation time was twenty-times longer than the heating time. The F− concentration once increased and then decreased with the reaction time, whereas the Cl− concentration increased continuously. The F−, once produced, may be consumed with the denatured molecular sieve. When the molecular sieve adsorbing 2-propanol together with CFC-113 was irradiated, the dechlorination proceeded by a chain reaction, but the defluorination was inhibited. On the other hand, when heated in the presence of 2-propanol, both the dechlorination and the defluorination were largely suppressed. The pH of the supernatant solutions decreased from an alkaline value to a neutral or acidic one along with dehalogenation. Radiolysis of CFC-113 on activated charcoal was also examined, but the dehalogenation rates were much slower than those on the molecular sieve.