Kinetics of photocatalytic disinfection in TiO2-containing polymer thin films: UV and visible light performances

The photocatalytic disinfection potential of TiO2- and Cu-, Zn- and Ag-promoted TiO2 embedded in polymer-based materials has been analyzed upon both ultraviolet and visible light excitations. A complete set of microorganisms including two Gram-negative (Escherichia coli and Pseudomonas earuginosa) and two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria and a yeast (Pichia jadinii) was used throughout the study. This series covers clinically and food derived infection relevant pathogens. A kinetic modeling using an adsorption Langmuir-Hinshelwood type mechanism was used to interpret the disinfection tests and the performance of the different TiO2 photo-biocide agents. The results clearly indicate that Ag- and Zn-containing materials are the most effective in all conditions tested (e.g. irrespective of the microorganism nature and light energy) and this seems intimately linked with intrinsic characteristics of the radical species reaching the surface of the polymer-oxide nanocomposite films as detected by electron paramagnetic resonance. (C) 2012 Elsevier B.V. All rights reserved.