Data/hora: 24/05/2024 22:55:07

Biblioteca(s): 	Embrapa Instrumentação.	
Data corrente: 	13/08/2004	
Data da última atualização: 	08/03/2010	
Autoria: 	GARBIN, J. R.; MILORI, D. M. B. P.; SIMÕES, M. L.; SILVA, W. T. L. DA; MARTIN-NETO, L.	
Título: 	Spectroscopical analysis of humic acids influence over the photolysis of aqueous pesticide residues.	
Ano de publicação: 	2004	
Fonte/Imprenta: 	In: INTERNATIONAL MEETING OF INTERNATIONAL HUMIC SUBSTANCES SOCIETY. -- IHSS, 12, São Pedro, SP, 2004. Humic substances and soil and water environment. Abstracts...[São Carlos], SP: Embrapa Instrumentação Agropecuária, 2004. p. 78.	
Idioma: 	Inglês	
Conteúdo: 	I. INTRODUCTION 
Pesticide residues are nowadays considered the second largest source of drink water contamination and this kind of residue rarely causes fast manifestation of diseases, but it presents a cumulative effect in the organism which can leads to cromossomal damages and carcinogen effects (Dubus et al., 2000, Helmuth et al., 2000). Several alternative methods have been proposed to solve this problem and special attention has been given to the use of UV light to promote the total degradatíon of the residues, because it's a non-selective method that brings the perspective to use sunlight for solving environmental problems (CYTED, 2001). Pesticide photolysis can occur by direct or indirect way (photocatalysis). Titanium dioxide (TiO2), a low cost, stable and non-toxic semiconductor, is the most commonly used photocatalyst which absorbs light around 360 nm, generating hydroxyl radicais (.OH) in the solution, which attack the pesticide molecules starting or accelerating their breakage. 
Humic substances (HS) can affect the photolysis and photocatalysis processes once these compounds to show intense absorption bands over UV range and they can quickly react with -OH. However, the entire mechanism of HS influence over pesticides photolysis remain still unknown (Kamiya and Kameyama, 1998 and Westerhoff et al., 1999). So, is necessary a better knowledge of HS effect on the process to use photolysis and photocatalysis by TiO2 for drink water treatment., because HS are naturally presents in lhe aquatic environment. 
The purpose of this work was to analyse the influence of different kinds and concentrations of HS over direct photolysis and photocatalysis of pesticides in aqueous solution, under UV-visible radiation (280-480nm). Were used UV-visible absorption and fluorescence emission spectroscopy to measure the pesticides photolysis rate and Electron Paramagnetic Resonance (EPR) spectroscopy measurements to attend the -OH photogeneration by HA during irradiation.	
Palavras-Chave: 	hydroxyl radical; Pesticidas; pesticides photolysis.	
Thesaurus Nal: 	humic acids.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Instrumentação (CNPDIA)	
Exemplares: 	CNPDIA - (8337-1) - UMT - SP - -- - PROCI-04.00015 -  - 2004.00015 - DIS
CNPDIA - (8571-1) - UMT - SP - -- - PROCI-04.00068 -  - 2004.00068 - DIS