Desenvolvimento, otimização e avaliação da viabilidade dos processos fenton e foto-fenton para a remediação de solos contaminados
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Data
2007-03-23
Autores
Dalla Villa, Ricardo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho foram estudados dois sistemas utilizando reações de Fenton e foto-Fenton para a remediação de solo contaminado com p,pþ DDT (DDT) e p,pþ DDE (DDE). O primeiro envolveu a formação de uma lama com o solo contaminado, na qual foram adicionados os reagentes de Fenton. No segundo, não houve a formação de lama e os reagentes foram adicionados diretamente ao solo por meio de um tubo injetor. No estudo foram avaliados diversos parâmetros que podem influenciar a reação de Fenton, tais como minerais de ferro naturalmente presentes no solo, irradiação solar e a concentração de Fe2+ e H2O2. A principal espécie mineral de ferro presente no solo é a hematita (Fe2O3), que teve pouca influência na degradação dos contaminantes. Nos experimentos com lama sem adição de ferro solúvel a porcentagem de degradação do DDT e DDE foi inferior a 25% e 4%, respectivamente, após 24 horas de reação. Nos ensaios com lama na presença de ferro solúvel e um excesso de H2O2, a degradação do DDT e DDE atingiu 75% e 40%, respectivamente em 32 horas. Nos experimentos sem lama, as porcentagens de degradação foram de aproximadamente 38% e 30% para o DDT e DDE, respectivamente, em 32 horas de experimento. Em ambos os sistemas de degradação, a irradiação solar teve pouca influência na degradação dos contaminantes. O sistema com lama, utilizando ferro solúvel e diferentes concentrações de H2O2, também foi estudado para a degradação de óleo diesel em solo, nestes ensaios até 80% da massa de óleo diesel foi degradada em 84 horas de reação. Durante a degradação do diesel também foi avaliado o efeito da textura do solo sobre a eficiência de degradação e foi observado que o aumento do teor de argila diminui a porcentagem de degradação. Em experimentos com solo Franco, cerca de 80% do diesel foi degradado enquanto que em solo Franco-argiloso a degradação foi inferior a 25%.
In this work two systems using Fenton and photo-Fenton for the remediation of a contaminated soil with p,pþ DDT (DDT) e p,pþ DDE (DDE) were studied. The first involved the formation of a slurry with the contaminated soil, where the Fenton's reagents were added. In the second system, a slurry was not formed and the reagents were added through an injector tube directly to the soil. The parameters that may influence the Fenton reaction, such as, the mineral iron originally present in the soil, solar irradiation and Fe2+ and H2O2 concentration were evaluated. The main mineral iron species in the soil is hematite (Fe2O3), which presented little influence on the contaminants degradation. In the slurry experiments without soluble iron addition, the degradation percentage of DDT and DDE were bellow 25% and 4% after 24 hours of reaction. In the slurry experiments in the presence of soluble iron and excess H2O2, the degradation of DDT and DDE reached 75% and 40%, respectively after 32 hours. In the experiments without slurry, the degradation percentages of DDT and DDE were 38% and 30%, respectively, after 32 hours of reaction. In both degradation systems, the solar irradiation had little influence on the contaminants degradation. The slurry system using soluble iron and different H2O2 concentrations, was also studied for the degradation of diesel oil in soil. In these experiments, about 80% of the diesel mass was degraded after 84 hours of reaction. For the diesel degradation, the effect of the soil texture on the degradation efficiency was also evaluated and it was observed that the increase of the clay content decreased the degradation percentage. In experiments with loam soil about 80% of the diesel was degraded whereas in clay loam soil the degradation was below 25%. Some adverse effects of the application of the Fenton process were also evaluated during the soil remediation.
In this work two systems using Fenton and photo-Fenton for the remediation of a contaminated soil with p,pþ DDT (DDT) e p,pþ DDE (DDE) were studied. The first involved the formation of a slurry with the contaminated soil, where the Fenton's reagents were added. In the second system, a slurry was not formed and the reagents were added through an injector tube directly to the soil. The parameters that may influence the Fenton reaction, such as, the mineral iron originally present in the soil, solar irradiation and Fe2+ and H2O2 concentration were evaluated. The main mineral iron species in the soil is hematite (Fe2O3), which presented little influence on the contaminants degradation. In the slurry experiments without soluble iron addition, the degradation percentage of DDT and DDE were bellow 25% and 4% after 24 hours of reaction. In the slurry experiments in the presence of soluble iron and excess H2O2, the degradation of DDT and DDE reached 75% and 40%, respectively after 32 hours. In the experiments without slurry, the degradation percentages of DDT and DDE were 38% and 30%, respectively, after 32 hours of reaction. In both degradation systems, the solar irradiation had little influence on the contaminants degradation. The slurry system using soluble iron and different H2O2 concentrations, was also studied for the degradation of diesel oil in soil. In these experiments, about 80% of the diesel mass was degraded after 84 hours of reaction. For the diesel degradation, the effect of the soil texture on the degradation efficiency was also evaluated and it was observed that the increase of the clay content decreased the degradation percentage. In experiments with loam soil about 80% of the diesel was degraded whereas in clay loam soil the degradation was below 25%. Some adverse effects of the application of the Fenton process were also evaluated during the soil remediation.
Descrição
Palavras-chave
Combustiveis diesel - Aspectos ambientais, Solos - Remediação, Solos - Contaminação, Soil
Como citar
DALLA VILLA, Ricardo. Desenvolvimento, otimização e avaliação da viabilidade dos processos fenton e foto-fenton para a remediação de solos contaminados. 2007. 140 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química, 2007.