SONOCHEMICAL DESTRUCTION OF CFC-11 AND CFC-113 IN DILUTE AQUEOUS-SOLUTION

The results of a preliminary, proof-of-principle investigation of the sonochemical destruction of the chlorofluorocarbons CFC 11 (fluorotrichloromethane) and CFC 113 (trifluorotrichloroethane) in dilute aqueous solution are reported. The chlorofluorocarbon solutions with an initial concentration of approximately 50 mg/L of the CFC were exposed to 20-kHz ultrasound with a power per unit volume of either 4.6 W/mL in a batch reactor or 0.64 W/mL in a circulating reactor. Destruction was fairly rapid with very little, less than 5%, of the CFCs undergoing volatilization. Destruction rates were slightly higher at 5 degrees C than at 10 degrees C. This decrease in reaction rate with an increase in solution temperature is common in sonochemistry. The solution pH decreased upon sonication, indicating the acidic species as a final halogen acceptor for at least a portion of the Cl and F.