Air desinfection in restricted environments by combining action of titanium and ultraviolet light (TiO2/UV) / Desinfecção do ar em ambientes confinados pela ação combinada de dioxido de titanio e luz ultravioleta (TiO2/UV)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The populational growth and development of new technologies and equipments to improve quality of life can many times contribute to an increase of polluent agents and the proliferation of pathogenic ones. Respiratory-tract diseases in Brazil have been an important cause of concern and hospitable internations. Several biochemical processes are under research and applied for air treatment and disinfection. Heterogeneous photocatalysis with titanium dioxide (TiO2/UV) is one of the advanced oxidatives process utilized due to several advantages of application: more efficiency on long term basis, production of lower tocity residues and high potencial at low cost of application. In this study a photocatalytic reactor was elaborated for collecting and treating environmental air samples from the Sanitization Laboratory located at UNICAMP, in Campinas, SP, from June 19th to July 28th of 2006. A total of 540 Petri dishes were analyzed in two different experiments, during morning, afternoon and night periods. At each experiment were utilized 135 dishes with culture media of Brain Heart Infusion Agar - BHI for bacteria and 135 other ones with Saboraud Dextrosis culture media for fungus. At each experiment the samples were submitted to four disinfection systems. In the Experiment 1 they were - S1: air collected from inside the reactor without TiO2/UV, S2: air collected from inside the reactor with one UV light and without TiO2 and S3: air collected from inside the reactor with two UV lights and without TiO2. In the Experiment 2 they were - S5: air collected from inside the reactor with TiO2 and without UV light, S6: air collected from inside the reactor with TiO2 and one UV light and S7: air collected from inside the reactor with TiO2 and two UV lights. Air samples were collected at ? 1, 2 and 3 minutes (t1, t2 and t3) time intervals for each experiment, with 15 replications (R) for each system. Bacteria colonies data were analyzed using qui-square tests for frequencies and non-parametric test of ?Friedman? at the levels of 1% and 5% of significance. Results from fungus colonies were analyzed by parametric test, with analysis of variance and tests of differences between average values, with previous transformation of data into ?N. Average data were compared by tests t and Tukey at the level of 5% of significance. Bacteria disinfection process of surrounding air is more efficient by using one or two UV-C lights inside the reactor with 1 and 3 minutes of exposition when are used heterogeneous photocatalysis (with TiO2) and photolysis (without TiO2) processes respectively. One minute time of exposition, with or without TiO2 inside the reactor is efficient for fungus removal, and germicide action was observed using one or two UV-C lights. The heterogeneous photocatalysis process (TiO2/UV) is an effective method for appropriate disinfection of microrganisms - fungus and bacteria, detected in the air of a restricted environmental from a laboratory, during one minute of exposition, with one or two UV-C lights.

ASSUNTO(S)

bacterias fungus ar-microbiologia fungos air microbiology heterogeneous photocatalysis fotocatalise catalise heterogenea bacteria

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