Visible light photocatalytic inactivation of Escherichia coli with combustion synthesized TiO2

The photocatalytic inactivation of Escherichia coli was studied with combustion synthesized TiO2 photocatalysts in the presence of visible light. A series of 400 W lamps irradiating in the visible region of the solar spectrum was used. The effect of various parameters, such as catalyst loading, light intensity, presence of inorganic ions, addition of hydrogen peroxide and pH, on the photocatalytic inactivation of E. coli was investigated. Photolysis alone had a small effect on inactivation while the dark experiment resulted in no inactivation and Ag/TiO2 showed the maximum inactivation. At a catalyst loading of 0.25 g/L, all the combustion synthesized catalysts showed better inactivation of E. coli compared to commercial Degussa P-25 (DP-25) TiO2 catalyst. An improved inactivation was observed with increasing lamp intensity and addition of H2O2. A negative effect on inactivation was observed by addition of inorganic ions such as HCO3−, SO42−, Cl−, NO3−, Na+, K+, and Ca2+. The photocatalytic inactivation of E. coli remained unaltered at different pH of the solution. The inactivation of E. coli was modeled with power law kinetics and was observed to follow first order kinetics.

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► The visible light photocatalytic inactivation of E. coli was studied.
► Ag/TiO2 showed the maximum inactivation.
► All synthesized catalysts showed higher inactivation than commercial TiO2.
► A negative effect on inactivation was observed by addition of inorganic ions.
► The visible light inactivation was observed to follow first order kinetics.