A influência das características dos solos na remediação de locais contaminados através de processos oxidativos avançados com persulfato e reagente de Fenton.

Abstract

Abstract:The remediation techniques used in contaminated soils such as "in situ" chemical oxidation aim essentially the mineralization of contaminants, reducing it to CO2 and H2O. The objective of this study is pointing out the results of experiments conducted to investigate how the soil characteristics such as granulometry, assay and nature of clay minerals as well as organic matter can influence in the mineralization performance of linear alkylbenzene in the soil. In some areas of São Paulo city there are contaminated sites by leakage of linear alkylbenzene and many other chemical leakages and site's responsible and local authorities are interested in possible technical solutions to clean it. One possible solution would be in situ treatment through advanced oxidation process; however there is no way how to decide about the best technique because it depends on contaminant substance, reagents used as well as the contaminated soil characteristics. The answer could be scientifically based on bench laboratory experiments properly designed to investigate the factors that control the process performance. The bench lab experiments were conducted with two soils sampled from metropolitan region of São Paulo and contaminated with linear alkyl benzene, used in high and medium voltage underground electrical cables. The mineralization performance was evaluated in soils contaminated with an initial concentration of 10 mg / gr of contaminated soil by oxidation of linear alkyl benzene with Fenton reagent and sodium persulfate. The final results pointed out a considerable mass reduction from 82% to 85% in both soils tested with sodium persulfate thermally activated and by naturally available transition metal Fe 2+ in the soil. The Fenton reagent in the same experiment conditions pointed out a more limited mass reduction performance between 10% and 30%. The previous knowledge of soil characteristics such as particle size ,clay assay , natural carbon content in the soil which influence the sorption / desorption phenomenon as well as the mineral composition of the soil are the key variables to define reagents and the oxidation reaction conditions which contribute to select a proper in situ chemical oxidation technology Keywords: Chemical oxidation. Contaminated soils. Advanced oxidation processes.Resumo: As técnicas de remediação para solos contaminados como os processos de oxidação avançados "in situ" visam essencialmente a mineralização dos contaminantes, reduzindo-os, em última instância, a CO2 e H2O. O objetivo deste estudo foi apresentar os resultados de experimentos conduzidos para investigar como as características do solo, tais como a granulação, o teor e a natureza dos minerais argilosos, e o teor da matéria orgânica influem no desempenho da mineralização do contaminante linar alquilbenzeno no solo. Na área metropolitana de São Paulo há locais onde os solos estão contaminados por esse e outros tipos de vazamentos e os responsáveis e as autoridades estão interessadas em possíveis soluções. Uma possível solução seria o trat...