Mechanism Reactions Of Photodegradation Of Organic Compounds Catalyzed By Tio2 [mecanismo De Fotodegradação De Compostos Orgânicos Catalisada Por Tio2]

Conventional technology used in the treatment of wastewater has been pointed as a major environmental problem for sustainable development, since minimization is not addressed accordingly. Advanced oxidation processes (AOP), based on the formation of hydroxyl radical (.OH), a powerful oxidant agent, have been considered to be a potential technology for the destruction of many toxic compounds. Photocatalysis using solar light, an AOP, has been studied for nearly 20 years and recently attracted great interest as a clean-up technology. However, solar detoxification processes have not yet achieved commercial success. This article presents an overview of reaction mechanisms at the surface of semiconductors used as photocatalysts (specially TiO2), when heterogeneous photocatalysis is used to remove hazardous compounds from contaminated sites.213319325Childs, L.P., Ollis, D.F., (1981) J. Catal., 67, p. 35Frank, S.N., Bard, A.J., (1977) J. Phys. Chem., 81, p. 1484Izumi, I., Fan, F.R.F., Bard, A.J., (1981) J. Phys. Chem., 85, p. 218Reiche, H., Dunn, W.W., Bard, A., (1979) J. Phys. Chem., 83, p. 2248Serpone, N., Borgarello, E., Harris, R., Cahill, P., Borgarello, M., Pelizzetti, E., (1986) Sol. Energy Mater., 14, p. 121Pruden, A.L., Ollis, D.F., (1983) Environ. Sci. Technol., 17, p. 628Pruden, A.L., Ollis, D.F., (1983) J. Catal., 83, p. 404Bekbölet, M., Lindner, M., Weichgrebe, D., Bahnemann, D.W., (1996) Sol. Energy Mater., 56, p. 455Hidaka, H., Yamada, S., Suenaga, S., Kubota, H., Serpone, N., Pelizzetti, E., Grätzel, M., (1989) J. Photochem. Photobiol., 47, p. 103Hidaka, H., Zhao, J., (1992) Coll. Surf., 67, p. 165Hidaka, H., Zhao, J., Pelizzetti, E., Serpone, N., (1992) J. Phys. Chem., 96, p. 2226Davis, R.J., Gainer, J.L., O'Neal, G., Wu, I.-W., (1994) Wat. Environ. Res., 66, p. 50Hustert, K., Zepp, R.G., (1992) Chemosphere, 24, p. 335Pelizzetti, E., Minero, Carlim, M., Vincentin, M., Pramauro, E., Dolsi, M., (1992) Chemosphere, 24, p. 891Chen, L.-C., Chou, T.-C., (1993) Ind. Eng. Chem. Res., 32, p. 1520Matthews, R.W., (1991) Wat. Res., 25, p. 1169Huang, M., Tso, E., Datye, A.K., Prairie, M.R., Stange, B.M., (1996) Environ. Sci. Technol., 30, p. 3084Alberice, R.M., (1992), Dissertação de Mestrado. Campinas, UNICAMPZiolli, R.L., (1995), Tese de Doutorado em preparaçãoHoffmann, M.R., Choi, W., Bahnemann, D.W., (1995) Chem. Rev., 95, p. 69Turchi, C.S., Ollis, D.F., (1990) J. Catal., 122, p. 178Fox, M.A., Dulay, M.T., (1993) Chem. Rev., 93, p. 341Linsebigler, A.L., Lu, G., Yates Jr., J.T., (1995) Chem. Rev., 95, p. 735Bredow, T., Jug, K., (1995) J. Phys. Chem., 99, p. 285Bredow, T., Jug, K., (1995) Surf. Sci., 327, p. 398Mo, S.D., Ching, W.Y., (1995) Phys. Rev. B., 51, p. 13023Wong, J.C.S., Linsebigler, A.L., Lu, G., Fan, J., Yates Jr., J.T., (1995) J. Phys. Chem., 99, p. 335Lu, G., Linsebigler, A.L., Yates Jr., J.T., (1995) J. Chem. Phys., 102, p. 4657Goniakowski, J., Noguera, C., (1995) Surf. Sci., 330, p. 337Serpone, N., (1995) Sol. Energy Mater., 38, p. 369Sun, Y., Pignatello, J.J., (1995) Environ. Sci. Technol., 29, p. 2065Gerischer, H., (1995) Electrochim. Acta., 40, p. 1277Mao, Y., Schöneich, C., Asmus, K.D., (1991) J. Phys. Chem., 95, p. 10080Carraway, E.R., Hoffman, A.J., Hoffmann, M.R., (1994) Environ. Sci. Technol., 28, p. 786Draper, R.B., Fox, M.A., (1990) Langmuir, 6, p. 1396Pelizzetti, E., (1995) Sol. Energy Mater., 38, p. 453Barreto, R.D., Gray, K.A., Anders, K., (1995) Wat. Res., 29, p. 1243Riegel, G., Bolton, J.R., (1995) J. Phys. Chem., 99, p. 4215Anpo, M., Chiba, K., Tomonari, M., Coluccia, S., Che, M., Fox, M.A., (1991) Bull. Chem. Soc. Jpn., 64, p. 543Pichat, P., Guillard, C., Amalric, L., Renard, A.C., Plaidy, O., (1995) Sol. Energy Mater., 38, p. 391Richard, C., Boule, P., (1995) Sol. Energy Mater., 38, p. 431Lu, G., Linsebigler, A.L., Yates Jr., J.T., (1995) J. Phys. Chem., 99, p. 7626Schwitzgebel, J., Ekerdt, J.G., Gerischer, H., Heller, A., (1995) J. Phys. Chem., 99, p. 5633Stafford, U., Gray, K.A., Kamat, P.V., (1994) J. Phys. Chem., 98, p. 634

Acute selenium selenite exposure effects on oxidative stress biomarkers and essential metals and trace-elements in the model organism zebrafish (danio rerio)

Selenium (Se) is an essential trace-element that becomes toxic when present at high concentrations. Little is known regarding Se effects on parameters such as oxidative stress biomarkers. The aim of the present study was to investigate the effects of acute selenium exposure on oxidative stress biomarkers in a model organism, zebrafish (Danio rerio). Fish were exposed to selenium selenite at 1mgL(-1). Reduced glutathione (GSH), and metallothionein (MT) concentrations were determined in liver, kidney and brain, with MT also being determined in bile. Essential metals and trace-elements were also determined by inductively coupled mass spectrometry (ICP-MS) in order to verify possible metal homeostasis alterations. GSH concentrations in liver, kidney and brain increased significantly (1.05±0.03μmolg(-1) ww, 1.42±0.03μmolg(-1) ww and 1.64±0.03μmolg(-1) ww, respectively) in the Se-exposed group when compared to the controls (0.88±0.05μmolg(-1) ww, 0.80±0.04μmolg(-1) ww and 0.89±0.03μmolg(-1) ww for liver, kidney and brain, respectively). MT levels in Se-exposed liver (0.52±0.03μmolg(-1) ww) decreased significantly in comparison to the control group (0.64±0.02μmolg(-1) ww), while levels in bile increased, albeit non-significantly. This is in accordance with previous studies that indicate efficient biliary MT action, leading to a rapid metabolism and elimination of contaminants from the body. Levels in the brain increased significantly after Se-exposure (0.57±0.01μmolg(-1) ww) when compared to the control group (0.35±0.03μmolg(-1) ww) since this organ does not present a detoxification route as quick as the liver-gallbladder route. Several metal and trace-elements were altered with Se-exposure, indicating that excess of selenium results in metal dyshomeostasis. This is the first report on metal dyshomeostasis due to Se-exposure, which may be the first step in the mechanism of action of selenium toxicity, as is postulated to occur in certain major human pathophysiologies.Selenium (Se) is an essential trace-element that becomes toxic when present at high concentrations. Little is known regarding Se effects on parameters such as oxidative stress biomarkers. The aim of the present study was to investigate the effects of acut336872CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOsem informaçãosem informaçãosem informaçãoThe authors are grateful to CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), CAPES (Coordenadoria de Aperfeiçoamento dos Professores do Ensino Superior), FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo), and Instituto Na

Bile And Liver Metallothionein Behavior In Copper-exposed Fish

The present study analyzed metallothionein (MT) excretion from liver to bile in Nile Tilapia (Oreochromis niloticus) exposed to sub-lethal copper concentrations (2mgL-1) in a laboratory setting. MTs in liver and bile were quantified by spectrophotometry after thermal incubation and MT metal-binding profiles were characterized by size exclusion high performance liquid chromatography coupled to ICP-MS (SEC-HPLC-ICP-MS). Results show that liver MT is present in approximately 250-fold higher concentrations than bile MT in non-exposed fish. Differences between the MT profiles from the control and exposed group were observed for both matrices, indicating differential metal-binding behavior when comparing liver and bile MT. This is novel data regarding intra-organ MT comparisons, since differences between organs are usually present only with regard to quantification, not metal-binding behavior. Bile MT showed statistically significant differences between the control and exposed group, while the same did not occur with liver MT. This indicates that MTs synthesized in the liver accumulate more slowly than MTs excreted from liver to bile, since the same fish presented significantly higher MT levels in liver when compared to bile. We postulate that bile, although excreted in the intestine and partially reabsorbed by the same returning to the liver, may also release MT-bound metals more rapidly and efficiently, which may indicate an efficient detoxification route. Thus, we propose that the analysis of bile MTs to observe recent metal exposure may be more adequate than the analysis of liver MTs, since organism responses to metals are more quickly observed in bile, although further studies are necessary. © 2013 Elsevier GmbH.2817074Rotchell, J.M., Clarke, K.R., Newton, L.C., Bird, D.J., Hepatic metallothionein as a biomarker for metal contamination: age effects and seasonal variation in European flounders (Pleuronectes flesus) from the Severn Estuary and Bristol Channel (2001) Mar. Environ. Res., 52, pp. 151-171Bremner, I., Mehra, R.K., Sato, M., Metallothionein in blood, bile and urine (1987) Experientia Suppl., 52, pp. 507-517Jaw, S., Jeffery, E.H., Role of metallothionein in biliary metal excretion (1989) J. Toxicol. Environ. 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Bull., 64, pp. 1589-1595Norris, D.O., Camp, J.M., Maldonado, T.A., Woodling, J.D., Some aspects of hepatic function in feral brown trout, Salmo trutta, living in metal contaminated water (2000) Comp. Biochem. Physiol. C Toxicol. Pharmacol., 127, pp. 71-78Galgani, F., Bocquene, G., Truquet, P., Burgeot, T., Chiffoleau, J.F., Claisse, D., Monitoring of pollutant biochemical effects on marine organisms of the French coasts (1992) Oceanologica Acta, 15, pp. 355-364McDonald, D.G., Wood, C.M., Branchial mechanisms of acclimation to metals in freshwater fish (1993) Fish Ecophisiol., 9, p. 448(2011), http://www.inea.rj.gov.br/, INEA. Available at(2003), http://www.mma.gov.br/, CONAMA. Available atRand, G.M., Petrocelli, S.R., (1985) Fundamentals of aquatic toxicology: methods and applications, , Hemisphere, New York, G.M. Rand, S.R. Petrocelli (Eds.)Erk, M., Ivankovi, D., Raspor, B., Pavicic, J., Evaluation of different purification procedures for the electrochemical quantification of mussel metallothioneins (2002) Talanta, 57, pp. 1211-1218Peterson, G.L., Review of the foline phenol protein quantitation method of Lowry, Rosebrough, Farr and Randall (1979) Anal. Biochem., 100, pp. 201-220Laemmli, U.K., Cleavage of structural proteins during assembly of head of bacteriophage-T4 (1970) Nature, 227, pp. 680-687Heukeshoven, J., Dernick, R., Simplified method for silver staining of proteins in polyacrylamide gels and the mechanism of silver staining (1985) Electrophoresis, 6, pp. 103-112Ellman, G.L., Tissue sulfhydryl groups (1959) Arch. Biochem. 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Assess., 156, pp. 361-375Richardson, D.M., Davies, I.M., Moffat, C.F., Pollard, P., Stagg, R.M., Biliary PAH metabolites and EROD activity in flounder (Platichthys flesus) from a contaminated estuarine environment (2001) J. Environ. Monit., 3, pp. 610-615Viarengo, A., Bettella, E., Fabbri, R., Burlando, B., Lafaurie, M., Heavy metal inhibition of EROD activity in liver microsomes from the bass Dicentrarchus labrax exposed to organic xenobiotics: role of GSH in the reduction of heavy metal effects (1997) Mar. Environ. Res., 44, pp. 1-11Pedersen, S.N., Lundebye, A.K., Depledge, M.H., Field application of metallothionein and stress protein biomarkers in the shore crab (Carcinus maenas) exposed to trace metals (1997) Aquat. Toxicol., 37, pp. 183-200Tsangaris, C., Strogyloudi, E., Papathanassiou, E., Measurements of biochemical markers of pollution in mussels Mytilus galloprovincialis from coastal areas of the Saronikos Gulf (Greece) (2004) Mediterr. Mar. 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Photocatalytic inactivation of Clostridium perfringens and coliphages in water

This study presents results of the photocatalytic inactivation of two groups of microorganisms: spores of the anaerobic bacterium Clostridium perfringens and coliphage. A cylindrical reactor impregnated with titanium dioxide and irradiated with ultraviolet light (15 W) was used. Parameters such as color, turbidity, hydraulic detention time (HDT) and initial concentration of microorganisms were evaluated in relation to the efficiency of the inactivation process. According to the experiments with the bacterium C. perfringens, the reduction in number of microorganisms was higher than 98% after an irradiation time of 152 seconds, independent of color and turbidity. For solutions with low turbidities efficiency of the coliphage inactivation reached approximately 100% between 89 and 104 HDT, while this value was 98% for solutions with higher turbidities