This work evaluated the use of the Hildebrand/Hansen solubility parameters for selection of solvents for extraction of the organochlorine pesticides pp' DDT, pp' DDE, Aldrin and a-Endossulfan from soil using columns packed with Al2O3. The mixtures hexane:dichloromethane (7:3; v/v), hexane:acetonitrile (1:1; v/v), hexane:acetone (1:1; v/v) and pure hexane were chosen as extracting solutions. In the addition and recovery tests, different extraction solutions provided high recoveries percentages (>75%) with coefficients of variation below 15%. The recoveries are in agreement with the Hildebrand/Hansen parameters, demonstrating its applicability in the selection of extracting solution and in the replacement of toxic solvents, as dichloromethane

Laboratórios e centros de pesquisa consomem uma grande variedade de substâncias químicas perigosas e, consequentemente, geram resíduos contendo-as, como por exemplo: resíduo de formaldeído. O formol é bastante empregado na conservação de peças anatômicas, gerando muitos litros desse resíduo por ano. O presente trabalho sugere o uso do processo foto-Fenton com irradiação solar para tratar resíduo contendo formaldeído. Alguns aspectos foram estudados como a concentração da fonte de ferro, da amostra e do peróxido de hidrogênio, além da aplicação de agitação magnética. O uso de ferrioxilato (0,5 mol L-1) mostrou ser mais eficiente na degradação da matéria orgânica quando comparado ao nitrato férrico. Já a concentração de peróxido necessária para tratar 500 mg C L-1 foi de 1 mol L-1. Sob essas condições todo formaldeído detectável foi degradado e foi possível remover 89% da matéria orgânica dissolvida na amostra em duas horas. Tais resultados são considerados satisfatórios para descartar na rede de esgoto, segundo a agência paulista de controle ambiental.

Laboratories consume great amounts of hazardous chemicals substances and consequently generate wastewater containing them, for example formaldehyde. This substance is widely utilized to preserve biological samples generating many liters of this residue every year. The present work proposes the use of the photo-Fenton process to treat formaldehyde wastewater using sunlight irradiation. Some aspects were investigated such as the iron source, sample and hydrogen peroxide concentration and also the use of stirred systems. The use of ferrioxalate (0.5 mmol L-1) improved the efficiency of the process in relation to the use of iron nitrate, while at least 1.0 mol L-1 H2O2 is necessary to treat the sample of the 500 mg C L-1. Under these conditions, every formaldehyde detectable was degradeted and 89% of the dissolved organic carbon was removed in two hours of exposure to sunlight. These results are satisfaction considerate for São Paulo State Environmental Agency.

Este trabalho descreve a utilização do processo Fenton para degradação de diesel em solo e destaca aspectos comuns em situações reais de contaminação que podem afetar a eficiência da remediação. Foi observado que a maior parte dos hidrocarbonetos presentes no diesel com menos de 14 carbonos foi perdida por volatilização antes da remediação. Em solo franco, cerca de 80% do diesel foi degradado enquanto que em solo franco-argiloso a degradação foi inferior a 20%. Adições múltiplas de H2O2 proporcionaram degradação de até 80% do diesel, enquanto que com adição única a degradação foi inferior a 14%. A adição de ferro solúvel foi essencial para obtenção de altas porcentagens de degradação. Não foi observado aumento significativo (t-test; P = 0.05) na degradação do diesel quando foram utilizadas dosagens de H2O2 entre 0,09 e 0,36 g g-1. Além disso, a alta dosagem de H2O2 (0,36 g g-1) degradou 87% da matéria orgânica originalmente presente no solo.

This work reports the use of Fenton process for diesel degradation and addresses common aspects of real situations that can affect the soil remediation efficiency. It was observed that most of diesel hydrocarbons containing less than 14 carbon atoms were lost by volatilization prior to the treatment. About 80% degradation was achieved in a loam soil, while less than 20% was observed in a clay loam soil. The multiple additions of H2O2 resulted in 80% diesel degradation, while only 14% of diesel was degraded after a reaction time of 80 h using a single addition. The addition of soluble iron was essential to achieve high degradation levels. No significant increase in diesel degradation (t-test; P = 0.05) was observed using H2O2 dosages between 0.09 and 0.36 g g-1. Furthermore, the highest H2O2 dosage applied (0.36 g g-1) degraded around 87% of the organic matter originally present in the soil.

Wastewater and soil treatment processes based on Fenton's reagent have gained great attention in recent years due to its high oxidation power. This review describes the fundaments of the Fenton and photo-Fenton processes and discusses the main aspects related to the degradation of organic contaminants in water such as the complexation of iron, the use of solar light as the source of irradiation and the most important reactor types used. An overview of the main applications of the process to a variety of industrial wastewater and soil remediations is presented.

Dairy wastewater is characterized by frequent episodes of drastic increases of organic content, giving rise to bulking filamentous bacteria and compromising the biological treatment process. This study reports the reduction of organic content of such wastewater by the application of the solar photo-Fenton process. For a wastewater containing 335, 2627 or 5400 mg C L-1 between 90% and 50% of the organic carbon content were removed after 3.5 h irradiation. The results show that the solar photo-Fenton process can be a good alternative for the abatement of organic content of dairy wastewater, especially in cases of organic content fluctuation, allowing an efficient biological treatment.

A flow injection spectrophotometric system was projected for monitoring hydrogen peroxide during photodegradation of organic contaminants in photo-Fenton processes (Fe2+/H2O2/UV). Sample is injected manually in a carrier stream and then receives by confluence a 0.1 mol L-1 NH4VO3 solution in 0.5 mol L-1 H2SO4 medium. The product formed shows absorption at 446 nm which is recorded as a peak with height proportional to H2O2 concentration. The performance of the proposed system was evaluated by monitoring the consumption of H2O2 during the photodegradation of dichloroacetic acid solution by foto-Fenton reaction.