A presença de substâncias húmicas em águas destinadas ao abastecimento tem ocasionado diversos problemas, entre eles a formação de subprodutos halogenados, principalmente quando se emprega a pré-oxidação com cloro. Com o reagente de Fenton não há a possibilidade de formação desses indesejáveis compostos halogenados, pois o forte poder oxidativo do reagente de Fenton é devido ao radical hidroxila (OH). Aliado a isto, com o mesmo produto químico se pode ter a pré-oxidação e coagulação de compostos orgânicos, pois o reagente de Fenton consiste na aplicação de íons de Fe+2 e peróxido de hidrogênio em meio ácido, sendo o Fe+2 oxidado a Fe+3. Como esses íons formam espécies hidrolisadas que atuam como coagulantes, o reagente de Fenton pode ter a dupla função de oxidação e coagulação nos processos de tratamento. Por isso, neste trabalho foi proposta uma metodologia para emprego do reagente de Fenton como agente coagulante no tratamento de águas contendo cor elevada causada pela introdução de substâncias húmicas extraídas de turfa. Além disto, foi estudado o efeito da massa molecular das substâncias húmicas na eficiência da coagulação, floculação e flotação de águas; para isto foram preparadas 4 águas distintas apresentado a mesma cor verdadeira, mas com substâncias húmicas de diferentes massas moleculares, obtidas por fracionamento por ultrafiltração. Por meio da otimização da dosagem de coagulante e respectivo pH de coagulação e posterior construção dos diagramas de coagulação para cada água de estudo, verificou-se que a água preparada com as substâncias húmicas de menor massa molecular apresentou maior grau de dificuldade para tratamento, requerendo dosagens de coagulante (reagente de Fenton) bem mais elevadas em relação às águas preparadas com substâncias húmicas de maior massa molecular. Adicionalmente, foram realizados ensaios de filtração em areia após a flotação, procurando-se simular tratamento em ciclo completo, tendo sido constatado que com o reagente de Fenton empregado como agente coagulante, a água filtrada atendeu ao padrão de potabilidade vigente no Brasil em relação aos parâmetros medidos (cor aparente < ou = 3 uH, turbidez < 0,5 uT e ferro total residual < 0,005 mg/L). Os valores de absorvância e carbono orgânico total da água filtrada também foram muito pequenos, indicando que a formação dos subprodutos da desinfecção com cloro seriam insignificantes. / Humic substances\' presence in water destined for supply has brought many problems, such as halogenated byproducts formation, mainly when chlorine is used as preoxidant. With Fenton\'s reagent there is no formation possibility of these undesirable halogenated compounds, since the strong oxidative power of Fenton\'s reagent is due to hydroxyl radical (OH). In addition, with the same chemical product, it is possible to have the preoxidation and coagulation of organic compounds, because Fenton\'s reagent consists of Fe+2 ions and hydrogen peroxide application under acid conditions, with Fe+2 oxidized to Fe+3. Since these ions form hydrolyzed species that act as coagulants, Fenton\'s reagent can have the double function of oxidation and coagulation on treatment processes. Because of this, the current work proposed a methodology to use Fenton\'s reagent as coagulant agent in the treatment of waters having high true color caused by the introduction of humic substances extracted by peat. Besides this, humic substances molecular weight effect on coagulation, flocculation and flotation of waters was studied; for this, 4 distinct waters having the same true color were prepared, but with different humic substances molecular weights, obtained by ultrafiltration fractioning. Through optimization of coagulant dosage and respective coagulation pH and posterior construction of coagulation diagrams for each studied water, it was verified that the water prepared withthe smallest molecular weight humic substances was more difficult to treat, requiring higher coagulant (Fenton\'s reagent) dosages compared with the waters prepared with larger molecular weight humic substances. Furthermore, experiments of filtration after flotation were carried out, trying to simulate a complete cycle treatment, which verified that with Fenton\'s reagent, employed as coagulant agent, the filtered water reached the brazilian potable standards concerning the measured parameters (apparent color < ou = 3 HU, turbidity < 0.5 TU and residual total iron < 0.005 mg/L). The absorbance and total organic carbon values of filtered water were also very low, indicating that the disinfection byproducts formation with chlorine would be insignificant.

M.Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / Water contaminated with non-biodegradable organics is becoming increasing problematic as it has a hazardous effect on human health and the aquatic environment. Therefore, the removal of organic contaminants is of importance and an active heterogeneous Fenton catalyst is thus required. The literature indicates that a bimetallic oxide Fenton catalyst is more active than an iron oxide catalyst. This study focused on increasing the activity of iron-based Fenton catalysts with the addition of transition metals such as manganese, cobalt and copper and optimizing the preparation method. In this study, bimetallic oxide (Fe-Cu, Fe-Mn, Fe-Co) and monometallic oxide (Fe, Cu, Mn,Co) catalysts supported on silica SiO2 where prepared by incipient wetness impregnation. The total metal oxide contents were kept constant. The catalysts where calcined in two different ways, in a conventional oven and in a microwave. These catalysts were characterized with XRD, XPS and CV and were tested for the degradation of methylene blue dye at 27°C. The catalysts calcined in a microwave oven had a higher catalytic activity than those prepared in a conventional oven. The bimetallic oxide catalysts outperformed the mono- metallic oxide catalysts in the degradation of methylene blue. The Fe2MnOx prepared by microwave energy were the most active catalyst yielding the highest percentage of degradation of methylene blue dye (89.6%) after 60 minutes. The relative amounts of manganese and iron oxide were varied while keeping the total metal content in the catalyst the same. The optimum ratio of Fe to Mn was 1:7.5 since it yielded the most active catalyst. A 96.6 % removal of methylene blue was achieved after 1 hour of degradation. Lastly this ratio 1Fe:7.5Mn was prepared by varying different microwave power (600, 700 and 800 W) and irradiation time (10, 20 and 30 min). The optimum microwave power and irradiation time was 800W and 10 min with the methylene blue percentage removal of 96.6 % after 1 hour of degradation.

PhD. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) causes morbidity and mortality in infected patients. These epidemics are significantly reduced and treated globally with antiretroviral drugs (ARVDs). However, the eventual disposal of the ARVDs, either by excretion or otherwise, enables them to end up as emerging hazardous contaminants in our environment. Of all the available methods to remove ARVDs from our water bodies, electrochemical methods are reckoned to be one of the most effective. As a result, it is imperative to acknowledge the interactive behavior of these pharmaceuticals on the surface of the electrode. In this study, iron nano-particles were deposited on the carbon cloth electrode by electrodeposition using chronoamperometry techniques. The synthesized electrode was characterized using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray photoelectron spectroscopy (XPS) microanalysis. The electrochemical characterization of the material was also carried out using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrode's electrocatalytic activity toward the generation of hydrogen peroxide (H2O2) through a two-electron oxygen reduction reaction was assessed. Furtherance to this is the electrochemical degradation of nevirapine (NVP), lamivudine (LVD), and zidovudine (ZVD) in wastewater as a pharmaceutical model compound for organic pollutants in 50 mM K2SO4 electrolyte at a pH of 3. The SEM and EDX analysis showed the formation of iron nanoparticles within the matrix structure of the carbon cloth (CC) electrode. The XPS enlightened the presence of oxygen functional groups in the electrode's structure. EIS results are indicative that the modified electrode has a decreased charge transfer resistance (Rct)value as compared to the bare CC electrode. On the other hand, the CV result fosters good conductivity, enhanced current and large surface area of the modified electrode. More active and anchor sites were discovered on the iron-supported CC electrode which resulted in higher catalytic activity for the generation and accumulation of H2O2. The concentrations of “in-situ” generated H2O2 were found to be related to the current density supplied to the device after quantification. Although the accumulated H2O2 concentration appears to be low, it's possible that side reactions depleted the amount of H2O2 produced. As a result, the oxygen reduction reaction (ORR) through 2e- has a higher electrocatalytic activity with the improved iron assisted CC electrode than bare CC electrode. The electrochemical degradation studies conducted with the modified CC electrode by electro-Fenton process show a decrease in the initial ARVDs concentration (20 mg/L) as compared with the bare electrode. Their rate constants were 1.52 x 10-3 mol-1min-1 for ZVD, 1.20 x 10-3 mol-1min-1 for NVP and 1.18 x 10-3 mol-1min-1 for LVD. The obtained removal efficiencies indicate that the iron nanoparticle in the synthesised improves the degradation efficiency.

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En la presente Tesis Doctoral se estudió la degradación de una mezcla de ocho compuestos fenólicos mediante diferentes procesos de oxidación avanzada. Se trataron mediante proceso foto-Fenton solar donde aplicando un diseño experimental tipo Doehlert se determinó que el proceso se puede extender hasta valores por encima de pH 2.8, probablemente debido a la formación de complejos del hierro con los compuestos fenólicos. En el tratamiento mediante ozono y la combinación de ozono con luz se estudió el efecto que la concentración de contaminante, el pH y la dosis de ozono tienen sobre el proceso. En general, la combinación del ozono con la luz resultó más eficaz en los casos más desfavorables, es decir, aquellos en los que la dosis de ozono era baja y/o el pH más ácido. La mineralización resultó ser superior en la combinación de ozono con luz y se alcanzó la detoxificación de las muestras en ambos ensayos. Se analizó la toxicidad mediante diferentes bioensayos, resultando el compuesto 2,4-dinitrofenol ser el más toxico para todos los ensayos. Para la monitorización de los contaminantes en los tratamientos, se midieron matrices de Excitación/Emisión (EMM) de fluorescencia. En el caso del proceso foto-Fenton, a los 12 minutos, todos los cromóforos habían desaparecido. En el tratamiento con ozono, se observa la aparición de nuevos cromóforos cuya intensidad va disminuyendo con el tiempo de tratamiento sin llegar a desaparecer por completo. Se han realizado matrices de Excitación/Emisión (EEMs) para estudiar la posible formación de complejos entre sustancias tipo húmicas (STH) y el hierro, así como los posibles cambios experimentados a lo largo del proceso foto-Fenton. Mediante análisis de factores paralelos (PARAFAC) se identificaron tres componentes. Se determinó la constante de estabilidad de los componentes con el Fe(III) a diferentes valores de pH, obteniéndose el máximo para pH 5. Los experimentos fotoquímicos empleando STH y Fe(III), en presencia y ausencia de H2O2, mostraron la dependencia del pH de los componentes modelados. En vista de la capacidad de las STH aisladas a partir de residuos urbanos de actuar como complejantes del Fe, se consideró la posibilidad de emplear otro tipo de residuos como material de partida; en concreto se empleó alperujo para la extracción de STH. Se probaron diferentes condiciones de extracción, obteniéndose los mejores resultados para valores de pH elevados y tiempos de digestión largos. Se comprobó la capacidad fotocatalíca de la STH extraídas y se profundizó en el estudio de la generación de especies radicales. Demostrada la utilidad de las EEMs y PARAFAC para profundizar en el conocimiento de mezclas complejas y teniendo en cuenta la dificultad que supone la aplicación del análisis matemático, se decidió colaborar en el desarrollo de una interfaz gráfica de usuario que facilitara dicho análisis. La aplicación EEMlab facilita la carga, pretratamiento y análisis mediante PARAFAC de sets de datos muy numerosos. Se creó un ejemplo con muestras que contenían mezclas de compuestos conocidos en diferentes proporciones y se empleó EEMlab para la corrección, preprocesamiento y análisis de los datos, validando la utilidad de la aplicación. / In this Doctoral Thesis, the degradation of a mixture of eight phenolic compounds by means of different advanced oxidation processes has been studied. An experimental methodology, based in Doehlert matrixes, was employed to analyze the effect of operational parameters on photo-Fenton process, and the results show that pH range can be extended clearly above 2.8, probably due to complexation of iron with the phenolic substances. In ozonation and ozone-UVA-Vis combination, the effect of pH, ozone dose and pollutants concentration were studied. Generally, O3/UVA-Vis was more efficient only in the experiments with worst operational conditions (low ozone dose and acid pH values). However, mineralization was better for the ozone UVA-vis combination. The toxicity was monitored along the degradation processes by means of different biotoxicity assays and in all cases a good detoxification was reached, being 2,4-dinitrophenol the most toxic pollutant. In order to monitor the pollutants along the treatment, excitation emission fluorescence matrixes (EEM) were recorded. In photo-Fenton process, chromophores were destroyed at 12 min of treatment. In ozonation, new chromophores appeared and partially disappeared at the end of the treatment. To gain further insight into the complexation of humic like substances (HLS) and Fe(III) and into the possible changes of the complex along the photo-Fenton process, EEMs were recorded and analyzed by PARAFAC (PARallel Analysis FACtor). Three fluorescent components were identified in all cases. The interaction of HLS with Fe(III) was characterized by determining the stability constants of the components with Fe (III) at different pH values, which reached their highest value at pH = 5. Photochemical experiments, with and without H2O2, showed pH-dependent trends for the modeled components. Taking into account the ability of humic substances to act as iron complexing agents, the possibility of employing olive mill wastes as a source of HLS was considered. Different extractions conditions were tested and best results were obtained for high pH values and long digestion times. Photocatalytic activity of the obtained substances was proved and the generation of reactive species was further studied. EEMs and PARAFAC seems to be a useful tool to gain further insight into complex mixtures, but the mathematical analysis in not easy. Taking this into account, we decided to collaborate in the development of a graphical user interface. The EEMlab application facilitates the load, preprocess and PARAFAC analysis of big data sets. An example dataset with already know mixtures of compounds at different concentrations was created. EEMlab was used to correct, preprocess and analyze the data set in order to probe the EEMlab utility. / En la present Tesi Doctoral es va estudiar la degradació d'una mescla de huit compostos fenòlics per mitja de diversos processos d'oxidació avançada. Es van tractar pel procés foto-Fenton solar, on aplicant un disseny experimental del tipus Doehlert es va determinar que el procés es pot estendre fins un valor per damunt de pH 2.8, probablement a causa de la formació de complexes del ferro amb els compostos fenòlics. En el tractament per ozó i la combinació ozó amb llum, es va estudiar l'efecte que la concentració del contaminant, el pH i la dosi d'ozó tenen en el procés. En general, la combinació d'ozó amb llum va resultar més eficaç en els casos més desfavorables, es a dir, aquells en els quals la dosi d'ozó era baixa i/o el pH més àcid. La mineralització va resultar ser superior en la combinació d'ozó amb llum i es va aconseguir la detoxificació de les mostres en ambdós assajos. Es va analitzar la toxicitat mitjançant diferent bioassajos, resultant el compost 2,4-dinitrofenol ser el més tòxic per a tot els assajos. Per a la monitorització dels contaminants en els tractaments, es mesuraren matrius de Excitació/Emissió (EEMs) de fluorescència. En el cas del procés foto-Fenton, als 12 minuts, tots els cromòfors havien desaparegut. En el tractament amb ozó, va observar-se l'aparició de nous cromòfors, la intensitat dels quals va disminuint amb el temps de tractament, sense arribar a desaparèixer completament. Es van realizar matrius de Excitació/Emissió (EMMs) per estudiar la possible formació de complexes entre les substàncies tipus húmiques (STH) i el ferro, així com els possibles canvis experimentats al llarg del procés foto-Fenton. Mitjançant l'anàlisi de factors paral·lels (PARAFAC) s'identificaren tres components. Es va determinar la constant de estabilitat dels components amb el Fe(III) a diferents valors de pH, obtenint-se'n el màxim per a un pH de 5. Els experiments fotoquímics empleant STH i Fe(III), en presència i absència de H2O2, mostraren la dependència amb el pH dels components modelats. En vista de la capacitat de les STH aïllades de residus orgànics urbans d'actuar com complexants del ferro, es va considerar la possibilitat d'utilitzar un altre tipus de residu com material de partida; concretament s'empleà el residu sòlid generat en l'obtenció de l'oli d'oliva en un procés en dos fases (pinyolada) per a l'extracció de STH. Es van provar diferents condicions d'extracció, obtenint-se'n els millors resultats per a valors de pH elevats i temps de digestió llargs. Es va comprovar la capacitat fotocatalítica de les STH extretes i es va profundizar en l'estudi de la generació d'espècies radicalàries. Demostrada la utilitat de les EMMs i PARAFAC per a aprofundir en el coneixement de mescles complexes i comptant amb la dificultat que suposa l'aplicació de l'anàlisi matemàtic, es va decidir colaborar en el desenvolupament d'una interfície gràfica d'usuari que facilitarà l'anàlisi. L'aplicació EMMlab facilita la càrrega, pretractament i anàlisi mitjançant PARAFAC de sets de dades molt nombrosos. Es va crear un exemple amb mostres que contenien mescles de compostos coneguts en diferents proporcions i es va emprar EEMlab per a la correcció, preprocessament i anàlisi de les dades, validant la utilitat de l'aplicació / García Ballesteros, S. (2017). DESARROLLO DE NUEVAS ESTRATEGIAS BASADAS EN LA INTEGRACIÓN DE PROCESOS FOTOQUÍMICOS SOLARES CON OTRAS TÉCNICAS AVANZADAS PARA EL TRATAMIENTO DE AGUAS RESIDUALES COMPLEJAS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/95602

No / Vitiligo is characterized by a progressive loss of inherited skin color. The cause of the disease is still unknown. To date, there is accumulating in vivo and in vitro evidence for massive oxidative stress via hydrogen peroxide (H2O2) and peroxynitrite (ONOO−) in the skin of affected individuals. Autoimmune etiology is the favored theory. Since depletion of the essential amino acid l-tryptophan (Trp) affects immune response mechanisms, we here looked at epidermal Trp metabolism via tryptophan hydroxylase (TPH) with its downstream cascade, including serotonin and melatonin. Our in situ immunofluorescence and Western blot data reveal significantly lower TPH1 expression in patients with vitiligo. Expression is also low in melanocytes and keratinocytes under in vitro conditions. Although in vivo Fourier transform-Raman spectroscopy proves the presence of 5-hydroxytryptophan, epidermal TPH activity is completely absent. Regulation of TPH via microphthalmia-associated transcription factor and l-type calcium channels is severely affected. Moreover, dopa decarboxylase (DDC) expression is significantly lower, in association with decreased serotonin and melatonin levels. Computer simulation supports H2O2/ONOO−-mediated oxidation/nitration of TPH1 and DDC, affecting, in turn, enzyme functionality. Taken together, our data point to depletion of epidermal Trp by Fenton chemistry and exclude melatonin as a relevant contributor to epidermal redox balance and immune response in vitiligo.

A problemática envolvendo os efluentes têxteis decorre principalmente da elevada coloração que apresentam, devido à presença de corantes que além de serem quimicamente estáveis, podem ser tóxicos e/ou carcinogênicos. Logo, quando são descartados in natura no meio ambiente causam problemas estéticos e, sobretudo, ambientais mesmo em baixas concentrações, além da possibilidade de serem nocivos à saúde humana e dos animais. Neste contexto, o objetivo deste trabalho foi estudar a degradação eletroquímica de dois corantes têxteis, Reativo Azul 19 (RA-19) e o Reativo Preto 5 (RP-5) via Oxidação Anódica (OA), utilizando ânodos de Diamante Dopado com Boro (DDB) suportados em titânio ou em nióbio, via processo Eletro-Fenton (EF) e pela combinação dos processos com H2O2 eletrogerado e OA (CP), usando um eletrodo de Carbono Vítreo Reticulado (CVR) como cátodo. As degradações foram realizadas em célula eletroquímica de um compartimento e em reator de fluxo do tipo filtro-prensa com dois compartimentos. A eficiência das degradações foi monitorada pelas técnicas de espectrofotometria no UV-VIS, Cromatografia Líquida de Alta Eficiência (CLAE) e análise do teor de Carbono Orgânico Total (COT). As variáveis estudadas foram densidade de corrente (10-100 mA cm-2 em célula e 4-41 mA cm-2 em reator), dopagem do eletrodo de DDB/Ti (5.000 e 15.000 ppm B/C), concentração inicial dos íons Fe2+ (0-0,10 mmol L-1) e dos corantes (10-250 mg L-1). As degradações dos corantes apresentaram uma cinética de pseudo ordem zero; exceto quando o corante RP-5 foi degradado pelo processo EF, sendo o melhor ajuste ao modelo de pseudo primeira ordem. Além disso, em iguais condições eletroquímicas o corante RP-5 foi degradado em menor tempo em relação ao RA-19; sendo que em todos os processos estudados os corantes foram totalmente removidos. Considerando a OA em célula com os eletrodos de DDB/Ti, a degradação foi positivamente influenciada pelo aumento da densidade de corrente e dopagem do eletrodo, especialmente em relação a cinética. Além disso, os corantes RA-19 e RP-5 foram completamente removidos em 35 e 50 min de eletrólise quando 100 mA cm-2 foi aplicada ao eletrodo de DDB/Ti dopado com 15.000 ppm relação B/C. Em 2 h, 37% em mineralização foi observado para ambos os corantes e a toxicidade do RA-19 diminuiu contra as bactérias Vibrio fischeri. Ainda nessa condição total mineralização foi alcançada após 8 h de degradação. A remoção de COT foi favorecida utilizando o reator contendo os eletrodos de DDB/Nb e CVR ao invés da célula eletroquímica, chegando a percentuais de 84 e 82% em 30 e 90 min para os corantes RA-19 e RP-5 que foram removidos em 7,5 e 5 min, respectivamente, quando a densidade de 41 mA cm-2 foi aplicada ao DDB/Nb durante a degradação via exclusivamente OA. Entre os processos realizados no reator, o EF foi o energeticamente mais favorável, promovendo remoção em COT de 60 e 74% para os corantes RA-19 e RP-5 com consumo energético de 204 e 208 kWh kg-1, além disso, a completa remoção dos corantes ocorreu em 15 e 7,5 min, respectivamente, quando o eletrólito continha íons Fe2+ na concentração de 0,10 mmol L-1 e aplicando-se -0,4 V vs Ag/AgCl ao eletrodo de CVR. Na degradação os corantes via CP o RA-19 e RP-5 foram completamente removidos em 30 e 15 min com mineralização de 72 e 82% em 90 min associada a consumos energéticos de 562 e 745 kWh kg-1, respectivamente, quando 41 mA cm-2 foi aplicada ao DDB/Nb. Por fim, concluiu-se que os resultados das degradações dos corantes foram promissores, já que rápida remoção dos corantes foi observada, além da parcial mineralização. Logo os processos propostos podem ser aplicados na remoção dos corantes em água; sendo necessários realizar mais estudos, principalmente em relação ao material eletródico e configuração do sistema eletroquímico visando a aplicação industrial. / The main problem involving the textile wastewater is theirs high coloration since they present dyes, which are chemically stable and can be toxic and/or carcinogenic. Therefore, when the textile wastewater are discarded in nature in the environment, even in low concentrations, they may cause not only aesthetic and environmental problems, but also can be harmful to human and animal health. In this context, the aim of the study was to evaluate the electrochemical degradation of two textile dyes, Reactive Blue 19 (RB-19) and Black 5 (RB-5) via Anodic Oxidation (AO) using as anodes Boron Doped Diamond electrodes (BDD) supported on titanium or niobium, via Electro-Fenton (EF) process and by combination of processes with electrogenerated H2O2 and AO (CP) using a Reticulated Vitreous Carbon electrode (RVC) as cathode. The degradations assays were carried out in an electrochemical cell with one compartment and in a filter-press flow reactor with two compartments. The efficiency of degradation was monitored by UV-VIS spectrophotometry, High Performance Liquid Chromatography (HPLC) and analysis of Total Organic Carbon (TOC). The variables studied were current density (10-100 mA cm-2 for cell and 4-41 mA cm-2 for reactor), doping of the BDD/Ti electrodes (5,000 e 15,000 ppm B/C), initial concentration of the Fe2+ ions (0-0,10 mmol L-1) and dyes (10-250 mg L-1). The kinetic results showed that the removal of dyes followed the model of pseudo zero order; except when the RB-5 dye was degraded by EF process, which the best fitted was to pseudo first order model. Furthermore, for equal conditions the RB-5 was degraded in less time in comparison to the RB-19. In addition, the dyes were fully removed in all the processes studied. Regarding the AO in cell with BDD/Ti, the degradation was positively influenced by the increasing in current density and doping of the electrode, primarily the kinetics parameters. In addition, total removal of RB-19 and RB-5 was achieved in 35 and 50 min of electrolysis when 100 mA cm-2 was applied to the electrode doped with 15,000 ppm ratio B/C. In 2 h, 37% in mineralization was attained for both dyes and the toxicity effect of the RB-19 decreased against the bacteria Vibrio fischeri. In this condition, total TOC removed was also reached after 8 h. The TOC removal was enhanced using the reactor fitted with BDD/Nb and RVC instead of the electrochemical cell, achieving TOC removal of 84 and 82% in 30 and 90 min for RB-19 and RB-5 which were removed in 7.5 and 5 min, respectively, when 41 mA cm-2 was applied to the BDD/Nb in the degradation exclusively via AO. Among the processes carried out in the reactor, the EF was the energetically most favourable since TOC removal of 60 and 74% for RB-19 and RB-5 with energy consumption of 204 and 208 kWh kg-1 were noted. In addition, the RB-19 and RB-5 were completely removed in 15 and 7.5 min, respectively, when the electrolyte containing 0.10 mmol L-1 of Fe2+ ions and -0.4 V vs Ag/AgCl was applied to CVR electrode. The combination of processes with electrogenerated H2O2 and AO for degradation of the dyes removed the RB-19 and RB-5 in 30 and 15 min with mineralization of 71.6 and 81.8% in 90 min associated to energy consumptions of 562 and 745 kWh kg-1 respectively, when 41 mA cm-2 was applied to BDD/Nb. Therefore, the degradation results of the dyes were promised since quickly removal of the dyes and partial mineralization were observed hence the proposed processes could be used to remove the dyes from water. However, more studies are needed to enable an industrial application, especially regarding the electrode material and configuration of the electrochemical system.

A indústria têxtil gera grandes volumes de efluentes com elevada carga orgânica, forte coloração e toxicidade. Neste trabalho, estuda-se o tratamento de solução aquosa contendo o corante Solophenyl Yellow Arle 154% por meio dos processos O3-H2O2/UV e foto-Fenton, avaliando-se as repostas: remoção de cor em 5 minutos, remoção de cor em 60 minutos, taxa máxima de remoção de cor e remoção de COT em 60 minutos. Os experimentos foram realizados em semibatelada com circulação usando um reator fotoquímico com campo de radiação anular coaxial, constituído de corpo cilíndrico em aço com refletor interno de alumínio para 12 lâmpadas fixadas simetricamente na superfície refletora e um tubo reator em quartzo de 0,7 L, posicionados verticalmente no eixo do refletor. Para o processo O3-H2O2/UV foram utilizadas lâmpadas Phillips TUV (36 W, 254 nm). A corrente gasosa contendo O3 foi introduzida no reator por meio de um difusor. Para o processo foto-Fenton foram utilizadas lâmpadas Sylvania (12 W cada, 300 400 nm) e concentração de Fe(II) de 0,25 mmol/L. Em ambos os processos, solução de peróxido de hidrogênio foi adicionada durante os 30 minutos iniciais de tratamento. As amostras foram analisadas por medidas de carbono orgânico total (COT) e remoção de cor (absorbância medida em 405 nm em espectrofotômetro UV-visível). Em ambos os processos utilizou-se o planejamento experimental Doehlert, definindo os valores mínimo e máximo para cada variável adotada. No caso do processo O3- H2O2/UV (ETAPA I), foram estudados os efeitos da potência elétrica total das lâmpadas (144 432 W), concentração de H2O2 (5 30 mmol/L), concentração inicial de corante (20 100 mg/L), concentração de ozônio (10 40 mg/L) e pH (3 10). No processo foto-Fenton (ETAPA II), estudaram-se os efeitos da potência (160 480 W), concentração de H2O2 (5 30 mmol/L) e concentração inicial de corante (20 100 mg/L). Os resultados da ETAPA I indicaram que o aumento da concentração do corante, em meio ácido, aumenta a remoção de cor em 5 e 60 minutos, sugerindo a eficiência da ação via ozônio molecular sob o grupo cromóforo do corante. Os melhores resultados apresentaram remoção acima de 95% em 5 e 60 minutos de tratamento. Entretanto, para a remoção de COT em 60 minutos o processo não foi eficiente, apresentando resultado máximo de 35,6%. Na ETAPA II obtiveram-se resultados menos satisfatórios para remoção de cor se comparados aos da ETAPA I (56,1% em 5 minutos e 78% em 60 minutos de tratamento), mas melhores em relação à remoção de COT em 60 minutos atigindo 45,1% de remoção. As maiores taxas de remoção de cor foram observadas nos 5 primeiros minutos de tratamento para todos os experimentos. Experimentos complementares realizados em uma terceira etapa (ETAPA III) mostraram que a aplicação do processo O3 seguido do processo foto-Fenton permitiu resultados satisfatórios tanto para remoção de cor (97,2%), quanto para remoção de COT (69,5%). O estudo da ação do processo O3 em modo contínuo e a avaliação econômica preliminar do processo integrado O3 - foto-Fenton sugerem o potencial de aplicação do tratamento integrado a indústrias têxteis. / The textile industry generates large volumes of wastewater with high organic load, strong coloration and toxicity. In this work, the treatment of an aqueous solution containing the dye Solophenyl Yellow Arle 154% was studied by the O3-H2O2/UV and photo-Fenton processes, in order to evaluate the responses color removal after 5 minutes; color removal after 60 minutes; maximum rate of color removal; and TOC removal after 60 minutes. The experiments were carried out in the semi-batch mode with circulation using a photochemical reactor with annular coaxial radiation field, consisting of a cylindrical stainless steel support with an aluminum internal reflector with 12 lamps fixed symmetrically in the internal reflecting surface, and a quartz tube reactor of 0.7 L, positioned vertically along the axis of the reflector. For the O3- H2O2/UV process, Phillips TUV lamps (36 W, 254 nm) were used; the gas stream containing zone was introduced into the reactor through a diffuser. For the photo- Fenton process, Sylvania lamps (12 W each, 300 - 400 nm) and a concentration of Fe (II) of 0.25 mmol/L were used. In both cases, the hydrogen peroxide solution was added in the first 30 minutes of treatment. The samples were analyzed by the measurement of total organic carbon (TOC) and color removal (absorbance measured at 405 nm in a UV-visible spectrophotometer). In both cases the Doehlert experimental design was used, defining the minimum and maximum values of each variable adopted. In the case of O3-H2O2/UV process (PHASE I), the effects of the total electric power of the lamps (144 - 432 W), H2O2 concentration (5 - 30 mmol/L), initial dye concentration (20 - 100 mg/L), ozone concentration (10 - 40 mg/L), and pH (3 - 10) were studied. For the photo-Fenton process, the studied variables were: total electric power of the lamps (160 - 480 W), H2O2 concentration (5 - 30 mmol/L), and initial dye concentration (20 - 100 mg/L). The results of PHASE I indicated that the increase of dye concentration in acidic conditions increases color removal after 5 and 60 minutes, thus suggesting the efficiency of molecular ozone action upon the chromophore group of the dye. The best results showed color removal above 95% after 5 and 60 minutes of treatment. However, for the TOC removal the process was not efficient, with maximum removal after 60 minutes of only 35.6%. In PHASE II less satisfactory results for color removal were obtained in comparison with PHASE I (56.1% after 5 minutes and 78% after 60 minutes of treatment), but with higher TOC removal after 60 minutes, achieving over 45.1%. The highest color removal rates were observed within the first 5 minutes of treatment for all runs. Additional experiments carried out in PHASE III showed that the oxidation by O3 followed by the photo-Fenton process enabled to achieve suitable results for both color (97.2%) and TOC removals (69.5%). The study of the O3 process in the continuous mode and a preliminary economic evaluation suggests a high potential for the use of the integrated O3-photo-Fenton process in textile industries.

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 é 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. Em várias partes da cidade de São Paulo há locais contaminados por esse e outros tipos de vazamentos e os responsáveis e as autoridades estão interessadas em possíveis soluções. Uma possível solução seria o tratamento in situ através dos processos de oxidação avançada. Porém, não há como decidir a priori sobre a melhor técnica, pois ela dependerá tanto do reagente empregado como do tipo de solo contaminado. Essa resposta poderá ser cientificamente fundamentada a partir de ensaios no laboratório desenhados para investigar os fatores que controlam a eficácia do processo. Os experimentos em laboratório foram conduzidos com dois tipos de solo da região metropolitana de São Paulo contaminados com linear alquilbenzeno, composto utilizado como óleo térmico em revestimentos de cabos subterrâneos de alta voltagem. Os desempenhos da mineralização com o Reagente de Fenton e Persulfato de Sódio foram avaliados na oxidação do composto linear alquilbenzeno com uma concentração inicial de 10 mg/grama de solo contaminado. Os resultados mostram uma redução considerável em massa de 82% a 85% do contaminante nos dois solos com a utilização de Persulfato de Sódio ativado termicamente e através de metal de transição \'Fe POT.2+\' disponível naturalmente no solo . O reagente de Fenton nas mesmas condições do experimento mostrou um desempenho mais limitado entre 10 % a 30% de redução em massa do contaminante. O conhecimento prévio das características do solo como o teor de argila , teor de carbono orgânico que influem fortemente os fenômenos de sorção e desorção e a composição mineralógica são variáveis importantes na definição dos reagentes e nas condições de reação de oxidação dos poluentes e contribuem na escolha mais acertada da tecnologia de remediação \'in situ\". / 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 pot.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 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.