Estudo da fotodegradação em águas: avaliação da degradação e toxicidade

Abstract

The pharmaceuticals and products of hygiene and care of personal contribute so beneficial for the improvement of the quality of life of human beings. One of these products is triclosan, (TCS), a bactericide used in formulating various toiletries, but when released into the environment, even in low concentrations of this compound and its derivatives are considered changers endocrine and can affect the reproductive physiology of several species. Due to the broad spectrum of applications and they are only partially eliminated in water treatment plants (ETA) and (ETE), these can be found in different aquatic compartments. On the exposed, this work had the objective of developing a methodology for heterogeneous photocatalysis, to promote complete mineralization of the TCS and evaluate the toxicity of by-products using microalgae, as test organisms. For this, we conducted a trial planning to determine the best operating conditions, with the variables mass of the catalyst, lamp power, time and pH, using dioxide titanium as photocatalyst. The results showed that 50 mg of TiO2 P25, power of 60 W, 180 minutes treatment and pH=5 were efficient, promoting 94.0% degradation of TCS. The photodegradation of TCS after 360 minutes of treatment, for TCS synthetic samples, using titanium dioxide and potassium hexaniobate as photocatalysts were 99.3% and 89.8%, respectively, showing that potassium hexaniobate is a good photocatalyst when compared to a traditional and commercial photocatalyst (TiO2 P25). The toxicity of samples after the photocatalytic treatment was determined by inhibition of the cell growth of microalgae and any sample completely inhibited the growth of microalgae cells, therefore, the treated effluent can be classified as being of low toxicity.