Inactivation of Escherichia coli by sonoelectrocatalytic disinfection using TiO2 as electrode

Abstract

This is the first study to demonstrate sonoelectrocatalytic disinfection using titanium dioxide (TiO2) as an anode for effective inactivation of Escherichia coli. In brief, a non-woven TiO2 fabric used as an anode and a platinum cathode were immersed in an E. coli suspension in which a positive potential was applied to TiO2 concomitant with ultrasound (US) irradiation. Two control experiments were performed using E. coli suspensions to exhibit the effects of the sonoelectrocatalytic disinfection. One was disinfection by applying a positive potential to a TiO2 electrode, but without US irradiation (electrochemical disinfection). The other was disinfection without applying a potential, but with US irradiation in the presence of TiO2 (sonocatalytic disinfection). The cell inactivation rate in sonoelectrocatalytic disinfection was synergistically much more enhanced than the combined inactivation rates in electrochemical disinfection and sonocatalytic disinfection. This synergistically enhanced inactivation rate of E. coli cells was attributable to effective reaction of the sonocatalytically generated OH radicals with E. coli cells at the surface of the TiO2 anode, which resulted from the electroadsorption of E. coli cells toward the TiO2 anode.