Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 79-88). Also available via the Internet.

Orientador: Marcelo Alexandre Prado / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-20T15:27:48Z (GMT). No. of bitstreams: 1 Beltramin_GabrielleDiasRosa_M.pdf: 5469686 bytes, checksum: 507fcd03670f5e77f40d07836a855261 (MD5) Previous issue date: 2012 / Resumo: O emprego de aditivos químicos em alimentos é um assunto que tem gerado bastante controvérsiaentre consumidores, indústrias, pesquisadores e governo. Exemplo são os corantes artificiais, aditivos bastante utilizados pela indústria de alimentos na coloração de seus produtos. Sem valor nutricional, seu uso é justificado apenas por questões alimentares. Em comparação com os corantes naturais, apresentam maior uniformidade, estabilidade e poder tintorial. Apesar das vantagens, evidências toxicológicas são consideravelmente maiores para os corantes artificiais e, apesar da alta estabilidade podem ter essa característica prejudicada por efeito de fatores físicoquímicos, como luz, temperatura e conservantes presentes na composição de alimentos e bebidas. Tendo em vista as características climáticas no Brasil e, levando em consideração sua enorme extensão, é de interesse analisar a estabilidade de corantes artificiais comumente utilizados em alimentos e bebidas comercializadas no país, uma vez que, a instabilidade desses corantes pode afetar a qualidade do produto, bem como causar riscos a saúde. Estudos comprovaram a influência de açúcares, ácidos ascórbico, sórbico, cítrico e benzóico na estabilidade de alguns corantes azo, porém, ácido cítrico em presença de ácido ascórbico ainda não foi abordado de forma minuciosa. Assim, o presente trabalho teve como objetivo estudar a estabilidade dos corantes tartrazina, amarelo crepúsculo e amaranto frente aos efeitos de luz, temperatura e presença dos ácidos ascórbico e cítrico, utilizando a técnica de espectrofotometria UV-visível. A estabilidade dos corantes também foi analisada em misturas de corantes para verificar a existência ou não de sinergia. Resultados demonstraram maior estabilidade dos corantes tartrazina e amarelo crepúsculo, independente das condições de estocagem. O amaranto apresentou alta instabilidade, principalmente em condições de alta temperatura e luz solar. Essas condições, de modo geral, provocaram maior instabilidade para os três corantes, que por outro lado, mantiveram-se estáveis em condição de escuro e baixa temperatura. A presença de ácido cítrico e ácido ascórbico provocou maior instabilidade dos corantes em todas as condições físicas testadas, exceto para a condição de escuro e alta temperatura, o qual apresentou estabilidade semelhanto ao grupo com presença apenas de ácido ascórbico. A análise de soluções com mistura de corantes garantiu, principalmente, maior estabilidade ao amaranto tanto na presença do amarelo crepúsculo quanto da tartrazina. Análises com bebidas coloridas artificialmente confirmaram o efeito da luz solar na diminuição da estabilidade dos corantes e da temperatura baixa na estabilidade desses compostos / Abstract: The adding of chemical additives in foods and beverages is a controversial issue between consumers, industries, researchers and government. Examples are artificial dyes, so used by food industries to color foodstuffs. With no nutritional value, use is only justified by alimentary habit. In comparison to natural dyes, they present higher uniformity, stability and coloring power. In spite of these advantages, toxicological evidences for artificial dyes are even higher than for natural ones and stability can be affected by physical-chemical factors, like for example, light, temperature and presence of preservative compounds in foods and beverages. Given the climatic characteristics in Brazil and taking into account its enormous extent, it is interesting to analyze the stability of artificial dyes commonly used in foods and beverages traded in the country, since the instability of these dyes can affect product quality as well as causing health risks. Researches have already proved sugar, ascorbic, sorbic, citric and benzoic acids influence on the stability of some azo dyes, though there are no information about citric and ascorbic acids influence together on the stability of tartrazine, sunset yellow and amaranth, neither when they are mixed with another artificial dye. Therefore, the aim of this study was to check the stability of tartrazine, sunset yellow and amaranth by the effects of light, temperature and presence of ascorbic and citric acid, using the technique of UV-visible spectrophotometry. Dyes¿ stability was also analyzed at dye mixtures to verify the existence of synergy. Results showed greater stability of tartrazine and sunset yellow, regardless of storage conditions. Amaranth was highly unstable, especially under conditions of high temperature and sunlight. These conditions generally caused greater instability for the three azo dyes. On the other hand, their color remained stable at dark and low temperature condition. The presence of citric and ascorbic acid caused greater instability of the dyes in all physical tested conditions, except for dark and high temperature condition, which presented the same stability of the group with only ascorbic acid. Analysis of dye mixture solutions ensured, especially, greater stability to amaranth in the presence of either sunset yellow or tartrazine. Analysis with artificially colored beverages confirmed the effect of sunlight in dyes¿ stability decrease and low temperature in the stability of these compounds / Mestrado / Ciência de Alimentos / Mestre em Ciência de Alimentos

Decolorization of Azo dyes in synthetic wastewater composition which is similar to real textile wastewater was carried out by microbial process. Experiments were performed in two continuous systems. Experiments were performed under anaerobic conditions in order to break the nitrogen bond of the azo group (-N=N-). A synthetic dye solution which contained 200 mg/L Reactive Black 5, 200 mg/L Procion Red MX-5B and 1 g/L yeast extract was prepared. In this study, living microorganisms were used to degrade the dyes in wastewater. Rice husks which contain bacteria and fungi were used in the reactors of continuous systems. The parameters tested on continuous system were wastewater composition, the number of reactors, the amount of yeast extract in wastewater composition, the wastewater flowrate, washing the system with wood chips solution, addition of yeast extract solution.  Results have shown that increasing the number of reactors, the retention time, the amount of yeast extract and washing the system with wood chips solution had positive effects for degradation of the dyes from wastewater. When the flowrate was increased the retention time has decreased so degradation of dyes has decreased but although the flowrate increased twice, % degradation hasn’t decreased as the same ratio. Therefore this result showed that this process can be worked for faster flowrates. Microbial process is a promising technology which might be used to treat wastewater containing azo dyes with good performance.

The removal of color and organic matter contributed by the azo dye, 'Reactive Black 5,’ and Navy 106 wash water from a textile mill were studied in sludges under aerobic and anaerobic conditions. The potential of the dyes to leach from landfills was also investigated using Toxicity Characteristic Leaching Procedure (TCLP) analysis. The vinyl sulfone group of the Reactive Black 5 dye appeared to enable the dye to sorb to biomass better than the hydrolyzed form of the dye. Sorption and aerobic color degradation of the hydrolyzed Reactive Black 5 dye and the Navy 106 wash water appeared to be related to biomass concentration. Little, if any, sorption or degradation of the dyes was observed with Blacksburg municipal treatment plant sludge which contained a biomass concentration of 3500 mg/L. However, sorption and degradation of wash water was observed with Peppers Ferry treatment plant sludge at a biomass level of 7000 mg/L. An inhibition to aerobic color removal of dye wash water was found at a higher color to biomass ratio. The inhibition to color degradation was accompanied by a lower rate of nitrate and sulfate release. TOC and COD of the dyes decreased under aerobic conditions. Under anaerobic conditions the color was degraded within a day. But the TOC and COD of the dye did not decrease. The TCLP extracts indicated the presence of little or no dye added to the reactors. / M.S.

by Stephen, Man-yuen Cheng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 124-141). / Abstract also in Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / List of Figures --- p.iv / List of Tables --- p.ix / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The development of dyes --- p.1 / Chapter 1.2 --- The chemistry of azo dyes --- p.2 / Chapter 1.3 --- "Evaluation of dyes submitted under the ""Toxic Substances Control Act"" new chemicals programme" --- p.6 / Chapter 1.4 --- Environmental concerns of dyes --- p.7 / Chapter 1.5 --- Decolorization techniques --- p.11 / Chapter 1.5.1 --- Activated sludge process --- p.11 / Chapter 1.5.2 --- Chlorination --- p.12 / Chapter 1.5.3 --- Fenton's reaction --- p.13 / Chapter 1.5.4 --- Ozonation --- p.13 / Chapter 1.5.5 --- Adsorption by activated carbon --- p.13 / Chapter 1.5.6 --- Chemical flocculation --- p.14 / Chapter 1.5.7 --- Coagulation --- p.14 / Chapter 1.5.8 --- Advance Oxidation Process --- p.15 / Chapter 1.5.8a --- Photocatalytic activation --- p.17 / Chapter 1.5.8b --- Enhancement of reaction rates of photocatalytic reaction --- p.21 / Chapter 1.5.9 --- Biosorption of azo dyes by Pseudomonas sp. K-l --- p.23 / Chapter 1.6 --- Water pollution in Hong Kong --- p.24 / Chapter 1.7 --- Purpose of study --- p.24 / Chapter 2 --- Objectives --- p.27 / Chapter 3 --- Materials and Methods --- p.28 / Chapter 3.1 --- Materials --- p.28 / Chapter 3.1.1 --- Azo dyes --- p.28 / Chapter 3.1.2 --- Biosorbent --- p.28 / Chapter 3.1.3 --- Chemicals --- p.28 / Chapter 3.2 --- Photocatalytic reactor --- p.31 / Chapter 3.3 --- Determination of the peak absorbance of five azo dyes at different pH --- p.31 / Chapter 3.4 --- Determination of dye concentration by measuring at peak absorbance --- p.37 / Chapter 3.5 --- Determination of pseudo-first-order rate constant --- p.37 / Chapter 3.6 --- Effect of initial concentration of procion red MX-5B on photocatalytic degradation --- p.39 / Chapter 3.7 --- Effect of initial concentration of hydrogen peroxide on photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.8 --- Effect of initial pH on the photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.9 --- Effect of initial temperature on the photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.10 --- Effect of titanium dioxide on the photocatalytic degradation of procion red MX-5B --- p.40 / Chapter 3.11 --- Effect of UV intensity in the photocatalytic degradation of procion red MX-5B --- p.41 / Chapter 3.12 --- Degradation kinetics of different dyes --- p.41 / Chapter 3.13 --- Degradation of 40 mg/L of procion red MX-5B under optimized conditions --- p.41 / Chapter 3.14 --- "Degradation of 1,000 mg/L of procion red MX-5B under optimized conditions" --- p.42 / Chapter 3.15 --- Temporal change of the concentration of procion red MX-5B in calcium alginate beads --- p.42 / Chapter 3.16 --- "Temporal change of the concentration of procion red MX-5B in alginate beads of 5,000 mg/L of Ti02" --- p.43 / Chapter 3.17 --- "Temporal change of the concentration of procion red MX-5B in alginate beads of 10,000 mg/L of Ti02" --- p.43 / Chapter 3.18 --- Effect of the concentration of titanium dioxide in alginate beads in the photocatalytic degradation of procion red MX-5B --- p.45 / Chapter 3.19 --- "Effect of hydrogen peroxide in the photocatalytic degradation of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.47 / Chapter 3.20 --- "Temporal change of the concentration of procion red MX-5B in alginate beads with 5,000 mg/L of Ti02" --- p.47 / Chapter 3.21 --- "Effect of biomass of Pseudomonas sp. K1 on the photocatalytic degradation of procion red MX-5B in alginate beads with 5,000 mg/L of Ti02" --- p.48 / Chapter 3.22 --- Diffuse reflectance-IR spectroscopic analysis of degradation product(s) --- p.49 / Chapter 3.23 --- Nuclear magnetic resonance (NMR) spectroscopic analysis of degradation products --- p.49 / Chapter 3.24 --- Toxicological evaluation of degradation products using Microtox® test --- p.51 / Chapter 4 --- Result --- p.54 / Chapter 4.1 --- Biosorption of dyes by Pseudomonas sp. K1 --- p.54 / Chapter 4.2 --- UV intensities of the eight Cole-Parmer UV lamps at 365 nm --- p.54 / Chapter 4.3 --- Determination of the peak absorbance of five azo dyes at different pH using scanning spectrophotometer --- p.54 / Chapter 4.4 --- Determination of dye concentration by measuring at peak absorbance --- p.66 / Chapter 4.5 --- Effect of initial concentration of procion red MX-5Bin photocatalytic degradation rate --- p.66 / Chapter 4.6 --- Effect of initial concentration of hydrogen peroxide on the photocatalytic degradation of procion red MX-5B --- p.73 / Chapter 4.7 --- Effect of initial pH on photocatalytic degradation of procion red MX-5B --- p.73 / Chapter 4.8 --- Effect of initial temperature on photocatalytic degradation of procion red MX-5B --- p.73 / Chapter 4.9 --- Effect of titanium dioxide on photocatalytic degradation of procion red MX-5B --- p.77 / Chapter 4.10 --- Effect of UV intensity on photocatalytic degradation of procion red MX-5B --- p.77 / Chapter 4.11 --- Photocatalytic degradation kinetics of different azo dyes --- p.77 / Chapter 4.12 --- Photocatalytic degradation of 40 mg/L of reactive red241 under optimized conditions --- p.77 / Chapter 4.13 --- Photocatalytic degradation of 40 mg/L procion red MX-5B under optimized conditions --- p.81 / Chapter 4.14 --- "Photocatalytic degradation of 1,000 mg/L of procion red MX-5B under optimized conditions" --- p.81 / Chapter 4.15 --- Temporal change of the concentration of procion red MX-5B in calcium alginate beads --- p.81 / Chapter 4.16 --- "Temporal changes of the concentration of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.85 / Chapter 4.17 --- "Temporal change of the concentration of procion red MX-5B in 10,000 mg/L of Ti02-alginate beads" --- p.85 / Chapter 4.18 --- Effect of the concentration of titanium dioxide in alginate beads in the photocatalytic degradation of procion red MX-5B --- p.89 / Chapter 4.19 --- "Effect of hydrogen peroxide in the photocatalytic degradation of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.89 / Chapter 4.20 --- "Temporal change of the concentration of procion red MX-5Bin alginate beads with 5,000 mg/L of Ti02" --- p.89 / Chapter 4.21 --- "Effect ofbiomass of Pseudomonas sp. K1 on the photocatalytic degradation of procion red MX-5B in 5,000 mg/L of Ti02-alginate beads" --- p.93 / Chapter 4.22 --- Degradation products analysis using diffuse reflectance-IR spectroscopy --- p.93 / Chapter 4.23 --- Degradation products analysis using nuclear magnetic resonance (NMR) --- p.101 / Chapter 4.24 --- Toxicological evaluation of degradation products using Microtox® test --- p.101 / Chapter 5 --- Discussion --- p.104 / Chapter 5.1 --- Biosorption of azo dyes in Pseudomonas sp. K-l --- p.104 / Chapter 5.2 --- Optimization of photocatalytic degradation of azo dyes --- p.105 / Chapter 5.2.1 --- Effect of initial concentration of procion red MX-5B on the photocatalytic degradation --- p.105 / Chapter 5.2.2 --- Effect of initial concentration of hydrogen peroxide on the photocatalytic degradation --- p.106 / Chapter 5.2.3 --- Effect of initial pH on the photocatalytic degradation --- p.107 / Chapter 5.2.4 --- Effect of initial temperature on the photocatalytic degradation --- p.108 / Chapter 5.2.5 --- Effect of titanium dioxide on the photocatalytic degradation --- p.109 / Chapter 5.2.6 --- Effect of UV intensity on the photocatalytic degradation --- p.110 / Chapter 5.2.7 --- Degradation kinetics of different dyes --- p.111 / Chapter 5.2.8 --- Optimized conditions for PCO of reactive red 241 and procion red --- p.112 / Chapter 5.3 --- Immobilization of titanium dioxide and Pseudomonas sp. K-l in alginate beads --- p.113 / Chapter 5.3.1 --- Temporal changes of the concentration of dye in alginate beads --- p.113 / Chapter 5.3.2 --- Effect of titanium dioxide in alginate beads in PCO --- p.114 / Chapter 5.3.3 --- Effect of hydrogen peroxide in alginate beads in PCO --- p.115 / Chapter 5.3.4 --- "Temporal change of dye concentration in alginate beads of 5,000 mg/L" --- p.115 / Chapter 5.3.5 --- Effect of biomass of Pseudomonas sp. K-l in alginate beads on the PCO of dye --- p.115 / Chapter 5.4 --- Diffuse reflectance IR spectroscopic analysis of degradation products --- p.116 / Chapter 5.5 --- 1HNMR analysis of degradation products --- p.119 / Chapter 5.6 --- Toxicological evaluation of degradation products using Microtox® test --- p.120 / Chapter 5.7 --- Application --- p.121 / Chapter 6 --- Conclusion --- p.122 / Chapter 7 --- References --- p.124 / Appendix 1 --- p.142 / Appendix 2 --- p.143

Nesta tese são apresentados os resultados de síntese e caracterização dos nanocompósitos de poli(anilina) (PANI) e de poli(benzidina)(PBZ) com argilas. Através do emprego de diferentes técnicas espectroscópicas e de microscopia eletrônica foi possível confirmar a intercalação dos monômeros e sua polimerização. Quando a polimerização foi feita a partir do monômero intercalado na argila (polimerização in situ) são obtidos nanocompósitos no qual a maior parte das cadeias poliméricas está intercalada. Entretanto, quando a polimerização é feita sem a prévia intercalação do monômero (polimerização ex situ), ocorre a formação dos polímeros na superfície externa da argila. Usando a espectroscopia Raman ressonante e de Absorção de raios-X na borda K do nitrogênio (N K XANES) foi possível elucidar a estrutura dos segmentos cromofóricos da PANI e da PBZ intercaladas, e pela primeira vez foi mostrado a presença de um segmento cromofórico na PANI intercalada, não presente na PANI livre, que possui em sua estrutura ligações azo e anéis cíclicos do tipo fenazina. A síntese da PANI intercalada em diferentes argilas e em diferentes condições de síntese permitiu verificar a influência destes fatores na formação desses novos segmentos. / The present work shows the synthesis and characterization of the nanocomposites of poly(aniline) (PANI) and poly(benzidine) (PBZ) formed inside the montmorillonite (MMT)clay galleries. Through the use of a large number of spectroscopic and microscopic techniques was possible to confirm the monomer intercalation and polymerization between the clay layers. When the synthesis is carried out after previous monomer intercalation (in situ route) the formation of polymer occurs mainly between the clay layers. On the other hand, the formation of polymer in external clay surface (ex situ route) occurs when the polymerization is carried out without previous monomer intercalation. Using resonance Raman spectroscopy and X-ray near nitrogen K-edge absorption (N K XANES) was possible to elucidate the structure of chromophoric segments in intercalated PANI and PBZ. For the first time, we show the presence of a new chromophoric segment, having phenazinic and azo groups, in the PANI intercalated by in situ route, indicating that the confinement of monomer is one of the factors leading to the formation of these new segments. The synthesis of intercalated PANI in different clays and experimental reaction conditions show that these factors, not only the confinement, have played an important role in formation of the new chromophoric segments in the structure of intercalated PANI.

La industria textil produce grandes cantidades de agua residual con un alto contenido de materia orgánica y color. Debido a la amenaza ambiental que supone su naturaleza refractaria, surge la necesidad del tratamiento antes de la descarga. Los procesos biológicos, físicos y químicos convencionales resultan ineficaces en la decoloración y mineralización completa de estos efluentes. Como alternativa emergen los Procesos Avanzados de Oxidación (PAOs), basados principalmente en la generación de radicales hidroxilo (HO·) altamente reactivos. Éstos pueden aplicarse de forma exclusiva o combinados con tratamientos biológicos con el fin de reducir su elevado consumo de reactivos y energía. Entre los diferentes PAOs disponibles, los procesos de Fenton y, particularmente, los procesos de foto-Fenton (basados en la generación de HO· mediante la adición de peróxido de hidrógeno y una sal ferrosa en disolución acuosa) suponen la mejor opción debido a su elevada eficacia y bajo coste económico. Adicionalmente, los procesos de foto-Fenton pueden llevarse a cabo bajo radiación solar, ofreciendo nuevas ventajas económicas y medioambientales. Esta tesis doctoral se centra básicamente en la aplicación del proceso de foto-Fenton como etapa previa en la degradación de soluciones de azo colorantes reactivos biorrecalcitrantes, con el propósito de generar un nuevo efluente compatible con un tratamiento biológico aerobio posterior de menor coste e impacto ambiental que el primero. La evolución de parámetros clave como el color, el carbono orgánico total, la aromaticidad, la toxicidad, la biodegradabilidad, la naturaleza de los intermedios de degradación, así como el efecto de la fuente de irradiación (luz artificial, luz solar), la temperatura, el tiempo de reacción y la concentración de reactivos, proporcionan información acerca de las condiciones idóneas para el acoplamiento PAO/tratamiento biológico. Los resultados obtenidos confirman la idoneidad del PAO propuesto con este fin, tanto a escala de laboratorio como en planta piloto. Mediante el proceso de foto-Fenton aplicado bajo condiciones de oxidación suaves, las soluciones bajo estudio resultan incoloras, de naturaleza biodegradable y no tóxica. De este modo, el tratamiento combinado foto-Fenton/tratamiento biológico aerobio permite su degradación completa. La luz solar como fuente de radiación en el proceso de foto-Fenton proporciona los mejores resultados. Por otro lado, la secuencia oxidativa parece comenzar por la decoloración por rotura del grupo azo seguida de la degradación de aromáticos para formar ácidos carboxílicos alifáticos -dando lugar a la formación de CO2 y H2O- o el anillo triazina de naturaleza recalcitrante. Una parte importante de los heteroátomos presentes en la molécula original aparecen como productos finales de naturaleza inorgánica inocua.El trabajo está ampliado con un estudio económico y medioambiental del proceso secuencial foto-Fenton (luz artificial)/tratamiento biológico. La evaluación medioambiental se ha realizado mediante la herramienta de Análisis de Ciclo de Vida. En comparación con los procesos simples foto-Fenton bajo luz artificial y foto-Fenton bajo luz solar, el tratamiento combinado resulta la mejor opción en ambos contextos. Los mayores impactos se asocian, en este orden, al consumo de peróxido de hidrógeno y de energía para alimentar la luz artificial. En consecuencia, y atendiendo a los resultados obtenidos previamente, es posible concluir que el proceso de foto-Fenton asistido con luz solar como pre-tratamiento de un proceso biológico sería la mejor opción en términos de efectividad, impacto medioambiental y coste operacional. Finalmente, como alternativa a la estrategia de oxidación química/tratamiento biológico aerobio, el PAO se aplica como post-tratamiento a un proceso biológico anaerobio. Los PAOs considerados son la ozonización y el proceso de foto-Fenton. Los resultados obtenidos manifiestan la idoneidad de la secuencia propuesta, obteniéndose unos mejores niveles de degradación mediante el proceso con ozono. Estos resultados son de especial interés en futuras aplicaciones para el tratamiento de aguas residuales textiles reales. / The textile industry produces large quantities of wastewater that is highly coloured and contains large concentrations of organic matter. Due to the environmental threat that supposes its recalcitrant nature, the application of specific treatment is required prior discharge. Conventional biological, physical and chemical processes are quite inefficient to completely mineralise and decolourise these effluents. Alternatively appear the Advanced Oxidation Processes (AOPs), principally based on the generation of highly reactive hydroxyl radicals (HO·). They may be applied as exclusive processes or combined with biological treatments in an attempt to reduce their large chemicals and energy consumption. Among available AOPs, the Fenton and, particularly, the photo-Fenton processes (based on HO· generation by means of hydrogen peroxide and a ferrous salt addition in aqueous solution) are of special interest since they achieve high reaction yields with a lower operational cost. Additionally, the photoassisted reaction presents the possibility of be driven under solar irradiation, offering further economic and environmental advantages. This doctoral dissertation is basically centred in the performance of the photo-Fenton process as a previous step to treat biorecalcitrant solutions polluted with commercial reactive azo dyes, aiming to generate a new effluent amenable to aerobic biotreatment (with a lower economic and environmental impact than the AOP). The evolution of key parameters such as the colour, the total organic carbon, the aromatic compounds content, the toxicity, the biodegradability, the generated by-products nature, as well as the type of irradiation effect (artificial light, solar light), the temperature, the reaction time and the reagents concentrations, provide information about the most suitable conditions to carry out the AOP/biological coupled treatment. Obtained results evidence the aptness of the AOP proposed with this aim, either at laboratory and pilot plant scale. With a partial oxidation run under proper mild conditions, the studied dye solutions become decolourised, biodegradable as well as non toxic. In this way, the combined photo-Fenton/biological treatment allows the complete mineralisation. The solar light as a source of irradiation provides the best results. On the other hand, the oxidative sequence appears to begin with the hydroxyl radical attack to azo groups, giving place to the solutions decolourisation. The following aromatics degradation generates either short chain carboxylic acids -finally yielding CO2 and water- or the recalcitrant triazine moiety. An important part of the heteroatoms initially present in the molecule gradually appear as innocuous final products of inorganic nature.The work is extended with an economic and environmental study of the sequential photo-Fenton (artificial light)/biological treatment process. The environmental evaluation has been realised by means of the Life Cycle Assessment tool. In comparison with single artificial light photo-Fenton process and solar driven photo-Fenton process, the combined treatment supposes the best option in both contexts. The major burdens are mainly attributed to the hydrogen peroxide requirements and the electrical energy consumption to run the artificial light, in this order. Consequently, and attaining to previously obtained results, the solar driven photo-Fenton process as a pre-treatment of a biological treatment would be the best option in terms of effectiveness, environmental impact and operational cost. Finally, as an alternative to the chemical/aerobic biological treatment, the AOP is performed as a post-treatment of an ensuing anaerobic biotreatment. Ozonation and photo-Fenton processes have been chosen for this role. Obtained results manifest the suitability of the proposed sequence, attaining the best degradation levels by means of ozonation process. These results are of special interest for real wastewater applications.

El objeto de la presente tesis es el desarrollo de metodologías analíticas rápidas para optimizar los procesos de degradación de colorantes orgánicos presentes en aguas residuales. Se ha llevado a cabo una revisión bibliográfica acerca de dichos procesos y las técnicas analíticas utilizadas para su monitorización y la identificación de posibles intermedios. Se han establecido nuevas metodologías analíticas basadas en herramientas quimiométricas tales como diseño de experimentos para optimizar procesos de fotodegradación con y sin catalizador. Se ha empleado resolución de curvas multivariante para la determinación simultánea de colorantes e intermedios durante estos procesos. Dado que la velocidad de degradación es el parámetro mas utilizado para evaluar la eficiencia de las fotodegradaciones se han evaluado todas las constantes involucradas en la degradación y/o la adsorción sobre el catalizador mediante HS-MCR-ALS. Se ha establecido una metodología analítica rápida para la determinación de colorantes basada en cromatografía de inyección secuencial (SIC). / The main aim of this thesis is the development of rapid analytical methodologies to optimize the photodegradation processes of organic azo dyes from industrial wastewater. A bibliographic review has been done concerning the most employed processes for dye removal and the analytical techniques used for the monitoring and the identification of intermediates. New analytical methodologies based on chemometric tools such as experimental designs have been established to optimize photodegradation processes with and without using heterogeneous catalysts. Multivariate curve resolution has been employed to determine simultaneously different dyes and intermediates along degradation processes. Since the degradation rate is the most employed parameter to evaluate the photodegradation efficiency all the kinetic constants involved in the degradation and/or the adsorption of the dye onto the catalyst have been evaluated by HS-MCR-ALS. Furthermore a rapid analytical methodology for dye determination based on sequential injection chromatography (SIC) has been established.

Η φωτοκαταλυτική διάσπαση υδατικών διαλυμάτων του Acid Orange 7 (ΑΟ7), ενός αζωχρώματος που αποτελεί τυπικό δείγμα των μη-βιοαποδομήσιμων χρωστικών ουσιών που απαντώνται στα υγρά απόβλητα βιομηχανιών υφαντουργίας, μελετήθηκε με χρήση καταλύτη TiO2 και τεχνητής ηλιακής ή ορατής (>400 nm) ακτινοβολίας. Βρέθηκε ότι όταν χρησιμοποιείται ηλιακή ακτινοβολία, η διάσπαση των μορίων του ΑΟ7 λαμβάνει χώρα στην επιφάνεια του φωτοκαταλύτη μέσω μιας σειράς βημάτων οξείδωσης που οδηγούν στον σχηματισμό ενδιαμέσων, κυρίως αρωματικών και αλειφατικών οξέων, τα οποία στη συνέχεια οξειδώνονται περαιτέρω προς ενώσεις με προοδευτικά μικρότερο μοριακό βάρος. Τελικά, επιτυγχάνεται πλήρης αποικοδόμηση του αζωχρώματος, με σχηματισμό CO2 στην αέρια φάση και ανόργανων ιόντων στο διάλυμα. Όταν χρησιμοποιούνται φωτόνια ορατού φωτός, τα ενδιάμεσα της αντίδρασης είναι παρόμοια με αυτά που παρατηρήθηκαν με τη χρήση ηλιακής ακτινοβολίας, αλλά ο αποχρωματισμός λαμβάνει χώρα με μικρότερους ρυθμούς. Επιπλέον, μετά τον αποχρωματισμό του διαλύματος, το COD δεν μειώνεται περαιτέρω και τα ενδιάμεσα της αντίδρασης μένουν σταθερά με το χρόνο ακτινοβόλησης υποδεικνύοντας ότι, στην περίπτωση αυτή, η φωτοκαταλυτική διάσπαση με χρήση ορατής ακτινοβολίας λαμβάνει χώρα μέσω του μηχανισμού “φωτοευαισθητοποίησης”. Σύμφωνα με τα αποτελέσματα της κινητικής μελέτης του συστήματος, ο αρχικός ρυθμός αποχρωματισμού εξαρτάται από την ένταση και το μήκος κύματος της προσπίπτουσας ακτινοβολίας, από την κάλυψη της επιφάνειας, από την αρχική συγκέντρωση του αζωχρώματος, από τη συγκέντρωση του TiO2 και από το αρχικό pH. Από την κινητική μελέτη προκύπτει κινητικό μοντέλο το οποίο περιγράφει ικανοποιητικά τα πειραματικά δεδομένα. Μελετάται η επίδραση των φυσικοχημικών ιδιοτήτων του φωτοκαταλύτη, όπως κρυσταλλογραφική δομή, ειδική επιφάνεια, μέσο μέγεθος κρυσταλλιτών, απορρόφηση στη UV/vis περιοχή και μορφολογία, καθώς και της μεθόδου παρασκευής του TiO2 στον ρυθμό αποχρωματισμού. Τέλος, διερευνάται η δυνατότητα βελτίωσης των φωτοκαταλυτικών ιδιοτήτων του TiO2 με ενίσχυση με διάφορα ετεροσθενή κατιόντα και με διασπορά μετάλλου στην επιφάνειά του. / The photocatalytic degradation of aqueous solutions of Acid Orange 7 (AO7), a model non-biodegradable textile azo-dye, is investigated with the use of TiO2 photocatalyst and artificial solar- or visible (>400 nm)-light irradiation. It is shown that when the full solar spectrum is utilized, the dye molecules adsorbed on TiO2 surface undergo a series of oxidation steps, which lead to rapid decolorization and formation of a number of intermediates, mainly aromatic and aliphatic acids, which are further oxidized toward compounds of progressively lower molecular weight and, eventually, to CO2 and inorganic ions. Under these conditions, complete decolorization and mineralization of the solution is achieved with appreciable reaction rates. When the solution is irradiated with visible light (λ> 400 nm), reaction intermediates are similar to those observed under artificial solar-light irradiation but decolorization takes place with much lower rates. In addition, when the solution is bleached, the COD does not further decrease with time of irradiation and reaction intermediates remain unchanged, indicating that the visible-light induced photocatalytic degradation of AO7 is governed by the “photosensitization mechanism”. Kinetic results show that the initial rate of decolorization depends on the intensity and the wavelength of incident light irradiation, the surface coverage, the initial concentration of the azo-dye, the concentration of the photocatalyst and the initial pH of the solution. From the kinetic investigation, a kinetic model is obtained which fits well the experimental data. The influence of the physicochemical properties of the photocatalyst such as crystal structure, specific surface area, average crystallite size, absorption in the UV/vis region and morphology, as well as the preparation method of TiO2 on the rate of decolorization is investigated. The improvement of the photocatalytic activity of semiconductor photocatalysts by doping with different altervalent cations and by deposition of noble metals onto the TiO2 surface is studied.

Darbo tikslas: dviem metodais gauti azodažiklius iš aromatinių aminų diazonio druskų, nustatyti jų pKa reikšmes, įvertinti spektrines savybes bei pritaikyti kaip indikatorius. Darbo uždaviniai: Gauti azodažiklius iš metilanilinų ir 4-nitroanilino vykdant jų diazonio druskų hidrolizę arba jungiant su 1-naftoliu bei 2-naftoliu, apskaičiuoti gautų junginių išeigas, nustatyti jų pKa reikšmes, spektrines savybes, galimą kaip indikatorių pritaikymą. Metodai: Tyrimui atlikti naudojami du azodažiklių sintezės metodai. Apskaičiuotos abiem metodais gautų azodažiklių procentinės išeigos. ESC įvertintas junginių grynumas. Gautų azodažiklių pKa reikšmės bei pH ribos, kuriose keičiasi jų spalva, vertinamos atliekant potenciometrinį titravimą. Vandeniniai azodažiklių tirpalai vertinti spektrofotometriškai, matuojant tirpalų absorbcijos maksimumus ir optinius tankius. Rezultatai: Azodažikliai, atliekant aromatinių aminų diazonio druskų hidrolizę (hidrolizatas sudarytas iš 44 ml vandens ir 20 ml koncentruotos H2SO4), gaunami veikiant aminus koncentruota HCl, kai hidrolizato temperatūra pakeliama iki 104-110 oC. Atliekant tradicinę azodažiklių sintezę išeigos yra geros-labai geros (vidutinė išeiga yra 76,95 proc.), o vykdant diazonio druskų hidrolizę – vidutinės (junginiai gaunami su vidutine 41,44 proc. išeiga). Tradiciniu metodu gautų naftolinių azodažiklių pKa reikšmės yra 8,8-11,0 ribose, o fenolinių, gautų atliekant eksperimentinę sintezę, - 7,5 8,0. Spektrofotometrinis tyrimas parodė... [toliau žr. visą tekstą] / Aim of the work: synthesis of azo dyes from aromatic amines diazonium salts by two methods, determination of their pKa values, spectral features and applicability as indicators of produced azo dyes. Main objectives: to obtain azo dyes from methylanilines and 4-nitroaniline by hydrolysis of their diazonium salts or by binding with 1-naphtol and 2-naphtol, to calculate yields of obtained compounds, to determine their pKa values, spectral features and their possible application as indicators. Methods: Two methods of azo dyes synthesis are used to perform the assay. Percentage yields of synthesized compounds, obtained by both methods, are calculated. Purity of compounds is evaluated by HPLC. pKa values and range of pH where the colour changes of received compounds are evaluated by potentiometric titration. Aqueous solutions of azo dyes are assessed by measuring absorption peaks and optical densities with a spectrophotometer. Results: it is necessary to synthesise aromatic amines diazonium salts with conc. HCl and to perform hydrolysis in 104-110 oC temperature when hydrolysate consist of 44 ml water and 20 ml conc. H2SO4 in order to obtain azo dyes by experimental method. Yields of traditional method are good-very good (average yield is 76,95 proc.), yields of experimental method are moderate (average yield is 41,44 proc.). pKa values of naphtolic azo dyes which are obtained by traditional method are 8,8-11,0 and phenolic azo dyes – 7,5-8,0. Spectrophotometric studies showed that... [to full text]