Efeito bactericida da luz solar e de lâmpada ultravioleta usando TiO2 sobre diferentes materiais suportes.

Abstract

Research on disinfection methods alternative to chlorination has been developed and among them the ultraviolet radiation and the heterogeneous photocatalysis stand out. In this job The bactericidal effect of sunlight and ultraviolet lamps using TiO2 (TiO2, TiO 2 / ZrO 2 and TiO 2 - N) on different material supports (rings and glass rods) for act as sensitizers in the light-mediated oxidation and reduction processes due to to its electronic structure. Transparent PET bottles were used to condition the water to be disinfected. The microorganisms used were pure strains of Escherichia coli (ATCC 25922), Samonella typhimurium (ATCC 3985), Staphylococcus aureus (ATCC 25923) and autochthonous water bacteria (thermotolerant coliforms). The monitored parameters were pH, turbidity, electrical conductivity, water temperature and radiation intensity ultraviolet. The control parameters of disinfection by solar and UV light were the density of pre and post disinfection bacteria and the reaction time. In order to evaluate whether there was reactivation of after irradiation ceased, the bottles were stored in the dark, and a new bacterial quantification was performed 24 and 48 hours after the experiment. The results show that the catalysts supported in the film form of TiO 2 / ZrO 2 and TiO 2 -N present high disinfection efficiency in waters with high concentrations of bacteria. At initial concentrations of bacteria, the structure of its wall (Gram-positive and Gram-negative), and the time of exposure to the radiation source, influence the death rate of microorganisms. The tested microorganisms, pure collection strains and autochthonous of the water, presented different degrees of photosensitivity for the different types of light, of catalyst and type of carrier used. Solar and UV radiation, in combination with heterogeneous photocatalysis, were efficient for disinfection of water intended for consumption (100% removal of Staphylococcus aureus, thermotolerant coliforms, Escherichia coli and Salmonella typhimurium), with no reactivation of the microorganisms irradiated, when different types of TiO2 catalyst films were combined, on glass pieces with more or less prolonged periods of irradiation.