Effects of pressure, temperature, and pH on the sonochemical destruction of 1,1,1-trichloroethane in dilute aqueous solution

There is an increasing interest in the application of high intensity ultrasound as an advanced oxidation technique. In this study, 1,1,1-trichloroethane (TCA) is the compound being subjected to ultrasonic irradiation. The study focuses on the effects of pressure (0.103-0.241 MPa), temperature (6-19.4 degreesC) and pH (3.96-12.5). Optimum conditions of treatment are discerned from the results of the experiments based on a center composite design. The results show that about 98% of TCA can be removed in 1 h of treatment (starting concentrations average 80 mg/l). Also, experiments indicate that the initial concentration does not affect destruction rate in this system. Optimum conditions as indicated by statistical analysis are at T = 14.2 degreesC, P = 0.212 MPa and pH = 10.9. This study also presents a method to normalize rate constants for changes in the power-to-volume ratio. (C) 2001 Elsevier Science B.V. All rights reserved.