Sonolytic enhancement of the bactericidal activity of irradiated titanium dioxide suspensions in water

Irradiated TiO2 suspensions in water were used to inactivate Escherichia coli and Hansenula polymorpha. Two types of batch reactors employing static and recirculating solutions were used in this study. Sonolysis using a 20 kHz ultrasonic unit was found to enhance the microorganism inactivation in all instances, although the enhancement was more modest for the batch recirculation reactor. These data are interpreted within the framework of four possible mechanisms. The mechanism based on sonolytic creation of . OH appears to provide the most satisfactory explanation of the data trends. The present data also implicate . OH as the dominant bactericidal agent in irradiated TiO2 suspensions.