Avaliação do TiO2 em filmes de tintas na degradação do corante laranja II e influência no desenvolvimento de larvas de Aedes aegypti

Abstract

In Brazil, climatic conditions were primordial for the adaptive success of the exotic species Aedes aegypti, which is highly synanthropic. The incidence of the mosquito is considered a public health issue, since it is a vector of dengue fever, Zika fever, and chikungunya, among other diseases. Preventive measures taken during the rainy season are decisive in the control of the Aedes aegypti, since the female places its eggs in supports where water accumulates. These substrates often represent difficult-to-view breeding sites and are usually exposed to solar radiation. Such exposure is suitable for the application of photocatalytic processes. Thus, the use of photocatalytic inks to cover the surface of these breeding sites constitutes a promising and innovative alternative to combat this vector. Photocatalytic paints are usually applied to combat air pollution. However, little is known about the functionality of these paints in aqueous matrices and under the influence of the polymer matrix and other compounds on the coating of the catalyst. Thus, two different paints and three different concentrations of photocatalyst (8%, 10% and 15% titanium dioxide) were tested. In order to test the influence of the weather in the photocatalytic process, surfaces which were coated with these paints were subjected to different treatment processes, consisting of immersion in water and exposure to solar radiation. Such surfaces were characterized according to morphology and composition (MEV / EDS), contact angle, Raman spectroscopy. The different surfaces were tested in a solution containing a template compound (azo orange dye II) and the influence of exposure of the paint to the weather was found to provide increased photocatalytic activity on a first use. After subsequent reuse stages, the inks obtained increased activity until reaching a similar value for each concentration, due to a greater exposure of the photocatalyst on the surface. After this step, new plates were coated with the photocatalytic ink (10% TiO2) and exposed to the immersion process in water and exposure to solar radiation for three days, in order to increase the initial photocatalytic activity of these surfaces. Then, their activity to impair the development of Aedes aegypti larvae was tested. The results did not indicate a significant difference (α = 5%) between the use of photocatalytic ink and UVA photolysis, yet they suggested higher percentage of larval mortality when the ink base (without TiO2) was used.