Analogies and differences between photocatalytic oxidation of chemicals and photocatalytic inactivation of microorganisms.
This study reports the analogies and differences found when comparing TiO(2) photocatalytic treatment for chemical oxidation and microorganisms inactivation, using methylene blue and Escherichia coli as references, respectively. In both processes the activation is based on the same physicochemical phenomena and consequently a good correlation between them is observed when analyzing the effect of operational variables such as catalyst concentration or incident radiation flux, both factors influencing common stages such radiation absorption and generation of reactive oxygen species. However, different microbiological aspects (osmotic stress, repairing mechanism, regrowth, bacterial adhesion to the titania surface, etc) makes disinfection kinetics significantly more complex than the first-order profiles usually observed for the oxidation of chemical pollutants. Moreover, bacterial inactivation reactions are found to be extremely sensitive to the composition of water and modifications of the catalysts in comparison with the decolorization of the dye solutions, showing opposite behaviors to the presence of chlorides, incorporation of silver to the catalysts or the use of different types of immobilized TiO(2) systems. Therefore, the activity observed for the photocatalytic oxidation of organics can not be always extrapolated to photocatalytic disinfection processes.
Marugán
Javier
J
Department of Chemical and Environmental Technology, ESCET, Universidad Rey Juan Carlos, C/ Tulipán s/n, 28933 Móstoles, Madrid, Spain.
van Grieken
Rafael
R
Pablos
Cristina
C
Sordo
Carlos
C
D002384:Catalysis / Q000187:drug effects / Q000528:radiation effects; D004926:Escherichia coli / Q000187:drug effects / Q000528:radiation effects*; D007700:Kinetics; D008027:Light; D008751:Methylene Blue / Q000737:chemistry*; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects*; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects; D014025:Titanium / Q000494:pharmacology*; D014867:Water
D014867:Water; C009495:titanium dioxide; D014025:Titanium; D008751:Methylene Blue