Análise de poluentes tóxicos no ar pelo método de ativação neutrónica

Abstract

Amostras de poluentes particulados foram irradiadas con nêutroes têrmico e analizados por espectometria de raios gama. Descreve~se os dois métodos experimentais usados para determinação desses poluentes, sendo que ambos os métodos de analise, foram nao destrutivos. No primeiro método se irradiaram amostras no Reator Argonauta do Instituto de Engenharia Nuclear, e foram realizadas medidas absolutas das atividades induzidas. Os resultados indicaram a presenca de bromo, sodio e cloro em concentrações acima dos limites de determinação quantitativa. Na descrição do método se faz um exame geral das interferencias, e da sensibilidade do método assim como também da precisão dos resultados obtidos o segundo método foi o método comparativo de analise, tendo sido as amostras irradiadas do Reactor Pulstar da North Carolina State University, num fluxo medio de 5 x 10(12) n/cm2 s. Foram identificados em torno de quinze elementos calculadas as suas conecntracoes e analizados os erros de medida.

Samples of air pollution particulates were irradiated with thermal neutrons and analyzed by gamma-ray spectrometry. Two experimental methods were used to determine the elemental concentration of the pollutants, and both methods of analysis were non-destructive. In the first method, samples were irradiated in the Argonaut Reactor at the Institute on Nuclear Engineering, and absolute measurements of the induced activities were made. The results indicated the presence of bromine, sodium and chlorine in concentration higher than the limits of the quantitative determination. A general examination and an evaluation of the sensitivity and precision of the method were made. In the description of the method a general examination of the interferences is made, and the sensitivity of the method as well as the precision of the obtained results. In the second method, a comparative analytical method was used, and the samples were irradiated in the North Carolina State University Pulstar Reactor to a thermal neutron flux of 5 x 10(12) n/cm2 s. About fifteen elements present were identified and their concentrations and measurement errors were analyzed.