This study determined the potential feasibility of surface catalyzed Fenton treatment to remediate soil and groundwater contaminated with bis(2-chloroethyl ether (BCEE), bis(2-chloroethoxy) methane (BCEM), and 1,2-dichloroethane (1,2-DCA) among other contaminants. Parameters that affect the contaminant loss rate such as pH, hydrogen peroxide concentration and solid/water ratio were systematically evaluated. Batch reactors were set-up utilizing either contaminated or uncontaminated soil that was mixed with synthetic groundwater containing the contaminants of interest. The results show an increase in contaminant reduction with a decrease in pH, an increase in hydrogen peroxide concentration, or an increase in the solid/water ratio. For the same set of conditions, contaminant reduction was greater for systems utilizing contaminated soil as compared to the systems containing uncontaminated soil. In addition, specific oxygen uptake rates were measured for an activated sludge exposed to different dilutions of untreated and surface catalyzed Fenton treated water to evaluate whether the residual BCEE, BCEM, and 1,2 DCA as well as their oxidation by products were potentially inhibitory or can potentially serve as a substrate for the activated sludge. The measured specific oxygen uptake rates show that the surface catalyzed Fenton treatment enhanced the biodegradability of the contaminated groundwater and served as a substrate for the activated sludge. / Master of Science

No description available.

Estágio realizado na Universidade de Granada e orientado pelo Prof. Maldonado-Hódar / Tese de mestrado integrado. Engenharia Química. Faculdade de Engenharia. Universidade do Porto. 2008

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 207-225).

A disposição ambientalmente adequada dos resíduos sólidos em aterros sanitários requer atenção ao tratamento do lixiviado gerado, que atualmente representa um desafio aos engenheiros, técnicos e pesquisadores da área. Esse trabalho avalia a tratabilidade do lixiviado pelo processo oxidativo avançado Reagente de Fenton, seguido por tratamento consorciado com esgoto sanitário em biofiltro aerado submerso. Os ensaios com Reagente de Fenton foram realizados em escala de bancada, com tempo de duração de 70 min por batelada; constatou-se que a razão mássica mais eficiente em termos de remoção de DQO do lixiviado bruto foi de 2:1 (H2O2:Fe II). Os resultados mostraram que esse tratamento reduziu, em média, 62% da DQO do lixiviado bruto. Entretanto, houve acréscimo do teor de sólidos no efluente e formação de lodo. Quanto ao tratamento consorciado com esgoto sanitário, foram utilizados dois biofiltros aerados submersos - reator controle (R1) e reator R2, que recebia 2% de lixiviado tratado por reagente de Fenton - com vazões de 330 mL/h e 450 mL/h, respectivamente, ambos com tempo de detenção hidráulica de 12 h. No período monitorado e considerando as eficiências médias de remoção de DQO de 75% e 70% e de DBO de 95% e 88% nos reatores R1 e R2, respectivamente, não foi possível concluir se houve tratamento do lixiviado ou apenas diluição. Entretanto, foi observado que a adição de lixiviado comprometeu a eficiência de remoção de matéria orgânica na forma de COD, no biofiltro R2. / The environmentally sound disposal of solid waste in landfills requires attention to the treatment of the leachate generated, which currently represents a challenge to the engineers, technicians and researchers. This research assesses the treatability of leachate by advanced oxidation process Fenton\'s reagent, followed by combined treatment with sewage submerged aerated biofilters. Assays with Fenton\'s reagent were performed in a bench scale, with a duration of 70 min per batch, it was found that the most efficient weight ratio in terms of COD removal of crude leachate was 2:1 (H2O2:Fe II). Results shows that treatment decreased on average 62% of the COD of the crude leachate. However, there was an increase of solids in the effluent and sludge formation. As for combination with sewage treatment, two submerged aerated biofilters were used - control reactor (R1) and R2 reactor, which received 2% of treated leachate by Fenton\'s reagent - with flows of 330 mL/h and 450 mL/h, respectively, both with a hydraulic retention time of 12 h. In the monitored period and considering the average COD removal efficiencies of 75% and 70% of BOD and 95% and 88% in the reactors R1 and R2, respectively, it was not possible to conclude whether there was treatment of leachate or just dilution. However, it was observed that the addition of leachate compromised the efficiency of removal of organic material in the form of COD in the biofilter R2.

Devido à alta toxicidade, a produção e comercialização dos PCBs (Polychlorinated Biphenyls - Bifenilas Policloradas) estão proibidas no mundo todo. Esses compostos foram utilizados principalmente como base de misturas comerciais em óleos dielétricos para transformadores e capacitores. Hoje existem diversas áreas contaminadas com essas substâncias que são de difícil degradação ocasionada pela sua elevada estabilidade térmica e química. Há diversos estudos sobre diferentes técnicas de tratamento de áreas contaminadas por PCBs. A técnica proposta nesse trabalho foi a de oxidação química através do reagente de Fenton. Para isso, foi simulado em laboratório experimentos de tratamento de solo contaminados artificialmente por ascarel (mistura comercial de PCBs). A oxidação foi realizada segundo a técnica do planejamento experimental fatorial de dois níveis e duas variáveis. Manteve-se constante a concentração do contaminante - em torno de 6000 mg de PCB/ kg de solo - e variou-se a concentração de Fe2+ (0,04 a 0,1 mol/L) e H2O2 (2,07 a 4,15 mol/L). Os ensaios foram realizados ainda nos seguintes tempos de reação: 0, 5, 24 e 48 horas. A análise dos dados foi realizada através de cromatografia gasosa acoplada a um espectrômetro de massa - GC/MS. Dos resultados, concluiu-se que o experimento cuja concentração do reagente de Fenton era 4,15 mol/L de H2O2 e 0,04 mol/L de Fe2+, apresentou melhor percentual de remoção, em torno de 76% para o pentaclorobifenila, 67% para o hexaclorobifenila e 72% para o heptaclorobifenila. Além disso, observou-se que, dentro da região experimental estudada, o efeito da concentração de íons ferrosos foi mais significativo do que o causado pela concentração de peróxido de hidrogênio e que o mesmo tem um efeito negativo pois aumentando a concentração dos íons ferrosos diminui-se a remoção dos contaminantes. / Production and trading of polychlorinated biphenyls (PCBs) are prohibited at whole world due to their high toxicity. They were used mainly as dielectric oils for transformers and capacitors. Recently there are many contaminated areas with these compounds. The high thermic and chemistry stability of PCBs are responsible for their hard degradation. Many studies have been conducted about several techniques of soil remediation. The main purpose of this research is to study chemical oxidation using Fenton\'s reagent to soils treatment. It was simulated in laboratory experiments of soil treatment which was artificially contaminated with Ascarel (PCBs commercial mixture). Process oxidation was made according to factorial experimental planning technique of two levels and two variables (22). The contaminant concentration was constant - 6000 mg PCB/ kg soil - and it was varied the Fe2+ concentration (0,04 mol/L to 0,10 mol/L) and H2O2 concentration (2,07 mol/L to 4,15 mol/L). The times reaction of experiments were: 0, 5, 24 and 48 hours. It was used gas chromatography coupled with mass spectrometer - GC/MS. The better result shown removal rate of 76% to pentachlorobiphenyl, 67% to hexachlorobiphenyl and 72% to heptachlorobiphenyl, experimental conditions were Fe2+ concentration of 0,04 mol/L and H2O2 concentration of 4,15 mol/L. Besides it was observed that studied region the concentration effect of ferrous ions was more significant than concentration effect of hydrogen peroxide. The concentration effect of ferrous ions was negative on system because removal rate of contaminants decreases when [Fe2+] increases.

A disposição ambientalmente adequada dos resíduos sólidos em aterros sanitários requer atenção ao tratamento do lixiviado gerado, que atualmente representa um desafio aos engenheiros, técnicos e pesquisadores da área. Esse trabalho avalia a tratabilidade do lixiviado pelo processo oxidativo avançado Reagente de Fenton, seguido por tratamento consorciado com esgoto sanitário em biofiltro aerado submerso. Os ensaios com Reagente de Fenton foram realizados em escala de bancada, com tempo de duração de 70 min por batelada; constatou-se que a razão mássica mais eficiente em termos de remoção de DQO do lixiviado bruto foi de 2:1 (H2O2:Fe II). Os resultados mostraram que esse tratamento reduziu, em média, 62% da DQO do lixiviado bruto. Entretanto, houve acréscimo do teor de sólidos no efluente e formação de lodo. Quanto ao tratamento consorciado com esgoto sanitário, foram utilizados dois biofiltros aerados submersos - reator controle (R1) e reator R2, que recebia 2% de lixiviado tratado por reagente de Fenton - com vazões de 330 mL/h e 450 mL/h, respectivamente, ambos com tempo de detenção hidráulica de 12 h. No período monitorado e considerando as eficiências médias de remoção de DQO de 75% e 70% e de DBO de 95% e 88% nos reatores R1 e R2, respectivamente, não foi possível concluir se houve tratamento do lixiviado ou apenas diluição. Entretanto, foi observado que a adição de lixiviado comprometeu a eficiência de remoção de matéria orgânica na forma de COD, no biofiltro R2. / The environmentally sound disposal of solid waste in landfills requires attention to the treatment of the leachate generated, which currently represents a challenge to the engineers, technicians and researchers. This research assesses the treatability of leachate by advanced oxidation process Fenton\'s reagent, followed by combined treatment with sewage submerged aerated biofilters. Assays with Fenton\'s reagent were performed in a bench scale, with a duration of 70 min per batch, it was found that the most efficient weight ratio in terms of COD removal of crude leachate was 2:1 (H2O2:Fe II). Results shows that treatment decreased on average 62% of the COD of the crude leachate. However, there was an increase of solids in the effluent and sludge formation. As for combination with sewage treatment, two submerged aerated biofilters were used - control reactor (R1) and R2 reactor, which received 2% of treated leachate by Fenton\'s reagent - with flows of 330 mL/h and 450 mL/h, respectively, both with a hydraulic retention time of 12 h. In the monitored period and considering the average COD removal efficiencies of 75% and 70% of BOD and 95% and 88% in the reactors R1 and R2, respectively, it was not possible to conclude whether there was treatment of leachate or just dilution. However, it was observed that the addition of leachate compromised the efficiency of removal of organic material in the form of COD in the biofilter R2.

Devido à alta toxicidade, a produção e comercialização dos PCBs (Polychlorinated Biphenyls - Bifenilas Policloradas) estão proibidas no mundo todo. Esses compostos foram utilizados principalmente como base de misturas comerciais em óleos dielétricos para transformadores e capacitores. Hoje existem diversas áreas contaminadas com essas substâncias que são de difícil degradação ocasionada pela sua elevada estabilidade térmica e química. Há diversos estudos sobre diferentes técnicas de tratamento de áreas contaminadas por PCBs. A técnica proposta nesse trabalho foi a de oxidação química através do reagente de Fenton. Para isso, foi simulado em laboratório experimentos de tratamento de solo contaminados artificialmente por ascarel (mistura comercial de PCBs). A oxidação foi realizada segundo a técnica do planejamento experimental fatorial de dois níveis e duas variáveis. Manteve-se constante a concentração do contaminante - em torno de 6000 mg de PCB/ kg de solo - e variou-se a concentração de Fe2+ (0,04 a 0,1 mol/L) e H2O2 (2,07 a 4,15 mol/L). Os ensaios foram realizados ainda nos seguintes tempos de reação: 0, 5, 24 e 48 horas. A análise dos dados foi realizada através de cromatografia gasosa acoplada a um espectrômetro de massa - GC/MS. Dos resultados, concluiu-se que o experimento cuja concentração do reagente de Fenton era 4,15 mol/L de H2O2 e 0,04 mol/L de Fe2+, apresentou melhor percentual de remoção, em torno de 76% para o pentaclorobifenila, 67% para o hexaclorobifenila e 72% para o heptaclorobifenila. Além disso, observou-se que, dentro da região experimental estudada, o efeito da concentração de íons ferrosos foi mais significativo do que o causado pela concentração de peróxido de hidrogênio e que o mesmo tem um efeito negativo pois aumentando a concentração dos íons ferrosos diminui-se a remoção dos contaminantes. / Production and trading of polychlorinated biphenyls (PCBs) are prohibited at whole world due to their high toxicity. They were used mainly as dielectric oils for transformers and capacitors. Recently there are many contaminated areas with these compounds. The high thermic and chemistry stability of PCBs are responsible for their hard degradation. Many studies have been conducted about several techniques of soil remediation. The main purpose of this research is to study chemical oxidation using Fenton\'s reagent to soils treatment. It was simulated in laboratory experiments of soil treatment which was artificially contaminated with Ascarel (PCBs commercial mixture). Process oxidation was made according to factorial experimental planning technique of two levels and two variables (22). The contaminant concentration was constant - 6000 mg PCB/ kg soil - and it was varied the Fe2+ concentration (0,04 mol/L to 0,10 mol/L) and H2O2 concentration (2,07 mol/L to 4,15 mol/L). The times reaction of experiments were: 0, 5, 24 and 48 hours. It was used gas chromatography coupled with mass spectrometer - GC/MS. The better result shown removal rate of 76% to pentachlorobiphenyl, 67% to hexachlorobiphenyl and 72% to heptachlorobiphenyl, experimental conditions were Fe2+ concentration of 0,04 mol/L and H2O2 concentration of 4,15 mol/L. Besides it was observed that studied region the concentration effect of ferrous ions was more significant than concentration effect of hydrogen peroxide. The concentration effect of ferrous ions was negative on system because removal rate of contaminants decreases when [Fe2+] increases.

One of the important factors determining the lifetime of polymer electrolyte membrane fuel cells (PEMFCs) is membrane degradation and failure. The lack of effective mitigation methods is largely due to the currently very limited understanding of the underlying mechanisms for mechanical and chemical degradations of fuel cell membranes. In order to understand degradation of membranes in fuel cells, two different experimental approaches were developed; one is fuel cell testing under open circuit voltage (OCV) with bi-layer configuration of the membrane electrode assemblies (MEAs) and the other is a modified gas phase Fenton's test. Accelerated degradation tests for polymer electrolyte membrane (PEM) fuel cells are frequently conducted under open circuit voltage (OCV) conditions at low relative humidity (RH) and high temperature. With the bi-layer MEA technique, it was found that membrane degradation is highly localized across thickness direction of the membrane and qualitatively correlated with location of platinum (Pt) band through mechanical testing, Infrared (IR) spectroscopy, fluoride emission, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) measurement. One of the critical experimental observations is that mechanical behavior of membranes subjected to degradation via Fenton's reaction exhibit completely different behavior with that of membranes from the OCV testing. This result led us to believe that other critical factors such as mechanical stress may affect on membrane degradation and therefore, a modified gas phase Fenton's test setup was developed to test the hypothesis. Interestingly, the results showed that mechanical stress directly accelerates the degradation rate of ionomer membranes, implying that the rate constant for the degradation reaction is a function of mechanical stress in addition to commonly known factors such as temperature and humidity. Membrane degradation induced by mechanical stress necessitates the prediction of the stress distribution in the membrane under various conditions. One of research focuses was on the developing micromechanism-inspired continuum model for ionomer membranes. The model is the basis for stress analysis, and is based on a hyperelastic model with reptation-inspired viscous flow rule and multiplicative decomposition of viscoelastic and plastic deformation gradient. Finally, evaluation of the membrane degradation requires a fuel cell model since the degradation occurs under fuel cell operating conditions. The fuel cell model included structural mechanics models and multiphysics models which represents other phenomena such as gas and water transport, charge conservation, electrochemical reactions, and energy conservation. The combined model was developed to investigate the compression effect on fuel cell performance and membrane stress distribution.

The focus of this research project was to investigate morphological and mechanical properties of both extruded and dispersion-cast Nafion® membranes. The project can be divided into three primary objectives; obtaining a fundamental understanding of the glass transition temperature of Nafion®, determining the effect of thermal annealing treatments on the morphology and mechanical properties of dispersion-cast Nafion®, and examination of dispersion-cast Nafion® subjected to an ex-situ, Fenton's chemical degradation test. Nafion®, a perfluorosulfonate ionomer, is considered a commercially successful semi-crystalline ionomer with primary applications in chlor-alkali cells and proton exchange membrane fuel cells. With the aid of dynamic mechanical analysis (DMA) and dielectric spectroscopy (DS), we were able to provide definitive evidence for a genuine glass transition in Nafion®. DMA of Nafion® samples that were partially neutralized with tetrabutylammonium counterions showed a strong compositional dependence suggesting that the β-relaxations of H+-form Nafion® and the neutralized ionomers have the same molecular origin with respect to backbone segmental motions. Building upon our previous studies of the molecular and morphological origins of the dynamic mechanical relaxations of Nafion® neutralized with a series of organic ions, the glass transition temperature of H+-form Nafion® is now confirmed to be the weak β-relaxation centered at -20 °C. Dielectric spectra also showed this transition from the perspective of dipole relaxation. The signature of cooperative long range segmental motions in dielectric spectra was seen here, as with other polymers, mainly through the excellent agreement of the β-relaxation time-temperature dependence with the Vogel-Fulcher-Tammann equation. We have also discovered that new dispersion-cast H+ form Nafion® membranes are susceptible to disintegration/dissolution when subjected to boiling methanol. In this work, we have achieved significant decreases in the percent solubility of H+-form Nafion® by either thermally annealing above 175 °C or solution-processing at 180 °C using a high boiling point solvent. Small Angle X ray Scattering (SAXS) displayed a change in the morphology of H+ form membranes with increasing annealing temperature by a shift in the crystalline scattering peak (q â 0.05 Ã 1) to lower q values. Counterion exchange of Nafion® from H+ to Na+ form had no influence on the membrane's susceptibility to disintegration in boiling methanol. In order to achieve mechanical stability in boiling methanol, Na+ form membranes had to be annealed at 275 °C for at least fifteen minutes. The SAXS data of annealed Na+ form membranes showed a dramatic decrease in crystalline order with annealing temperature, ultimately leading to the disappearance of the crystalline scattering peak after fifteen minutes at 275 °C. The onset of methanol stability with the melting of Nafion® crystallites suggests that chain entanglement is an important parameter in obtaining solvent stability. With respect to chemical stability, we performed studies aimed at examining the effects of Fenton's Reagent on the resistance to radical attack of new generation, dispersion-cast Nafion®. Changes in the 19F solid-state NMR spectra of dispersion-cast Nafion® before and after chemical degradation via Fenton's Reagent predicts a rather random attack by ·OH and ·OOH radicals. Several membranes were also thermally annealed between 100-250 °C in an attempt to correlate crystallinity with chemical degradation kinetics of Nafion® via Fenton's Reagent. The results indicate that the effect of counterion exchange into the Na+ form was minimal, but the degree of thermal degradation had a tremendous effect on the fluoride release rate and chemical degradation kinetics. By exchanging the membranes into the Na+ form, thermal degradation was avoided, allowing us to study the role of crystallinity as a function of fluoride release. Ultimately, Nafion® crystallinity was deemed an important factor in deterring peroxide radical attack. As the percent crystallinity decreased with annealing temperature, the fluoride concentration in the resulting Fenton's media increased accordingly, indicating that the amorphous regions of the polymer are more susceptible to chemical degradation via peroxide radical attack. / Ph. D.