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Master's Dissertation
DOI
10.11606/D.85.2006.tde-22052007-143631
Document
Author
Full name
Kelly Cristina Santana de Almeida
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Duarte, Celina Lopes (President)
Oliveira, Joselene de
Saraiva, Elisabete de Santis Braga da Graca
Title in Portuguese
"Avaliação da contaminação da água do mar por Benzeno, Tolueno e Xileno na região de Ubatuba e estudo da degradação destes compostos por radiação ionizante"
Keywords in Portuguese
btx
radiacao ionizante
ubatuba
Abstract in Portuguese
O principal problema relativo aos acidentes com vazamentos de óleos combustíveis nos ambientes marinhos e costeiros é a contaminação pelos compostos benzeno, tolueno e xileno, (BTX), que possuem toxicidade elevada. O objetivo deste trabalho foi avaliar a contaminação da água do mar por BTX na região de Ubatuba, SP, entre 23º26’S e 23º46’S de latitude e 45º02’W e 45º11’W de longitude, que é uma área de transporte e produção de petróleo e estudar a eficiência da remoção destes compostos pela exposição à radiação ionizante proveniente de uma fonte de 60Co. A metodologia analítica utilizando o sistema de concentração “Purge and Trap” e o cromatógrafo CG-DIC, apresentou maior sensibilidade em água do mar do que o sistema de concentração “headspace” associado ao cromatógrafo CG-EM, com limite mínimo de detecção, LMD, de 0,50 μg/L de benzeno, 0,70 μg/L de tolueno e 1,54 μg/L de xileno com uma variabilidade experimental (N=10) de cerca de 15%. Enquanto que o sistema CG-EM apresentou um LMD de BTX em água do mar de 9,30 mg/L para o benzeno, 8,50 mg/L para o tolueno e 9,80 mg/L para o xileno, com uma variabilidade experimental calculada nas mesmas condições de cerca de 10%. Foram realizadas quatro coletas de novembro de 2003 a julho de 2005 e a concentração de benzeno na água do mar variou de 1,0 μg/L a 2,0 μg/L, a de tolueno variou de <0,70 μg/L a 3,24 μg/L e para o xileno o valor máximo detectado foi de 2,92 μg/L. No caso das amostras de água do mar contaminadas com padrões de BTX e expostas à radiação ionizante, a eficiência de remoção para o benzeno foi menor do que para os outros compostos considerando-se as mesmas concentrações, a taxa de remoção variou de 10% a 40% para dose absorvida de 20kGy e concentrações de 35,1 mg/L a 70,2 mg/L, respectivamente. O tolueno apresentou 20% a 60% de remoção para concentrações similares, mas com 15kGy de dose absorvida. Finalmente, o xileno foi removido com eficiência de 20% a 80% e 15 kGy de dose absorvida.
Title in English
EVALUATION OF SEAWATER CONTAMINATION WITH BENZENE, TOLUENE AND XYLENE IN THE UBATUBA NORTH COAST, SP REGION, AND STUDY OF THEIR REMOVAL BY IONIZING RADIATION
Keywords in English
btx
ionizing radiation
ubatuba
Abstract in English
A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23º26’S and 23º46’S of latitude and 45º02’W and 45º11’W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 μg/L for benzene, 0.70 μg/L for toluene, and 1.54 μg/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 μg/L to 2.0 μg/L, the concentration of toluene varied from < 0.70 μg/L to 3.24 μg/L and the maximum value of xylene observed was of 2.92 μg/L. The seawater samples contaminated with BTX standard and exposed to ionizing radiation using a source of 60Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations.
 
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Publishing Date
2009-03-17
 
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