Application of the photocatalytic reaction of TiO2 to disinfection and the killing of Escherichia coli bacteria

Abstract

Photocatalytic disinfection reaction under UV- visible light in presence of
oxygen and Titanium dioxide (TiO2) in aqueous solution has been investigated .This
method is effective for killing Escherichia -coli bacteria in water. TiO2 semiconductor
exhibits strong bacterial activity .The aim of this research is to design a new
photobioreactor and its application to sterilize the water from E-coli bacteria .
Primary experiments have been done to determined the optimum conditions
which lead to high killing efficiency of E-coli bacteria in aqueous solution . The results
showed that the bacterial effect of TiO2 under UV-visible light irradiation on E-coli
bacterial suspension was much higher than without using TiO2 .The photocatalytic
reactions were carried out with various TiO2 concentrations. The highest photocatalytic
E-coli photokilling rate was obtained at 0.5 mg/ml TiO2 concentration ,which is equal
to 3.25 x 10-2 CFUs /sec .This rate was increased to 5.8 x10-2 CFUs /sec when 10
ppm of hydrogen peroxide was add to E-coli aqueous solution under UV- visible light
in presence of oxygen and ideal concentration of TiO2 (0.5mg/ml). The mechanism of
TiO2 illumination to produce oxidizing species and the effect of these species on the
bacterial activity in aqueous solution has been suggested.