Desenvolvimento de uma unidade laboratorial para quantificação de BTX como poluentes atmosféricos, usando microextração em fase sólida
This dissertation aims the development of an experimental device to determine quantitatively the content of benzene, toluene and xylenes (BTX) in the atmosphere. BTX are extremely volatile solvents, and therefore play an important role in atmospheric chemistry, being precursors in the tropospheric o...
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| Формат: | Dissertação |
| Язык: | por |
| Опубликовано: |
Universidade Federal do Rio Grande do Norte
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| Предметы: | |
| Online-ссылка: | https://repositorio.ufrn.br/jspui/handle/123456789/15813 |
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| Итог: | This dissertation aims the development of an experimental device to determine quantitatively
the content of benzene, toluene and xylenes (BTX) in the atmosphere. BTX are extremely
volatile solvents, and therefore play an important role in atmospheric chemistry, being
precursors in the tropospheric ozone formation. In this work a BTX new standard gas was
produced in nitrogen for stagnant systems. The aim of this dissertation is to develop a new
method, simple and cheaper, to quantify and monitor BTX in air using solid phase microextraction/
gas chromatography/mass spectrometry (SPME/CG/MS). The features of the
calibration method proposed are presented in this dissertation. SPME sampling was carried
out under non-equilibrium conditions using a Carboxen/PDMS fiber exposed for 10 min
standard gas mixtures. It is observed that the main parameters that affect the extraction
process are sampling time and concentration. The results of the BTX multicomponent system
studied have shown a linear and a nonlinear range. In the non-linear range, it is remarkable
the effect of competition by selective adsorption with the following affinity order p-xylene >
toluene > benzene. This behavior represents a limitation of the method, however being in
accordance with the literature. Furthermore, this behavior does not prevent the application of
the technique out of the non-linear region to quantify the BTX contents in the atmosphere. |
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