Enhancement of phage inactivation using photocatalytic titanium dioxide particles with different crystalline structures

To investigate the effect of crystalline structures on biocidal activity of TiO2 particles, the photocatalytic deactivation of phage MS2 was conducted using the mixture of anatase- and rutile-type TiO2 particles under irradiation with a black light lamp. Apparent deactivation rate constant, k′, was determined by applying the first-order kinetics to the time profiles of phage deactivation and the k′ value was found to be maximized at anatase ratio of Ran = 70 wt%. Considering the quantity of phage particles adsorbed on TiO2 surfaces, qT, it was also found that the k′/qT value at Ran = 70 wt% was 4.3 and 5.4 times, respectively, as compared with those at Ran = 0 and 100 wt%. The kinetic analysis of phage deactivation supported the consideration that the close contact between both types of TiO2 particles caused the enhancement of quantum yield and thereby the increased generation of reactive oxygen species in TiO2 photoreaction.