O trabalho tem por objetivo a aplicação de técnicas de modelagem molecular como ferramenta de pesquisa em Engenharia Química, em particular no estudo das reações químicas envolvidas na degradação do fenol em processos oxidativos avançados. Os resultados obtidos para reações em fase gasosa mostram que o uso dessa ferramenta, no nível de teoria selecionado (B3LYP/6-31++G(d,p)), é adequado para descrever a maioria das reações do mecanismo proposto. As constantes cinéticas calculadas (através da Teoria do Estado de Transição), quando comparadas com os dados experimentais disponíveis, encontram-se dentro da mesma ordem de grandeza para a rota mais viável. A simulação de um par de reações paralelas mostra o mesmo perfil de queda do fenol encontrado para as constantes cinéticas experimentais. A comparação com resultados teóricos prévios mostra que a adição de efeitos de polarização das nuvens eletrônicas ao conjunto de base resulta em um aperfeiçoamento nos valores das constantes cinéticas. Os estudos do meio solvatado mostram que o modelo de solvatação implícita SM5.42R é adequado para descrever o sistema, por reproduzir bem o valor experimental da energia de solvatação do fenol. Entretanto, não é possível fazer comparações quanto aos radicais devido à ausência de dados experimentais. Dentre os modelos de solvatação explícita construídos, o modelo que conta com uma esfera de solvatação de 4 moléculas de água se mostrou melhor para o fenol. Já para o intermediário radicalar O1, o modelo mais adequado foi o que conta com 6 moléculas de água formando um ciclo sobre as hidroxilas ligadas ao anel. Com os resultados obtidos e suas comparações com valores experimentais discute-se a aplicabilidade de técnicas de Modelagem Molecular em estudos aplicados em Engenharia Química, reforçando a visão desta ferramenta como um instrumento importante no projeto de novos produtos e na otimização de processos de interesse tecnológico. / This work has the main objetive of applying molecular modeling techniques as a research tool in Chemical Engineering particularly on the study of the chemical reactions involved in the degradation of phenol by Advanced Oxidation Processes. The obtained results for gas phase reactions show that the use of this tool, in the selected level of theory (B3LYP/6- 31++G(d,p)) is adequate to describe most of the reactions within the proposed mechanism. The calculated kinetic constants (through Transition State Theory), when compared with the available experimental data, were found to be within the same order for the most likely pathway. The simulation of a parallel reactions pair shows the same declining profile found for experimental kinetic constants. The comparison with previous theoretical results suggest that the addition of polarization effects on the basis set results in a higher accuracy of the kinetic constant values. The studies of the continuum show that the implicit solvation model SM5.42R is adequate to describe the system, since it reproduces well the experimental value of solvation energy for phenol. However, it is not possible to do comparisons for the radicals due to the absence of experimental data. Among the explicit solvation models constructed, the one which represents a solvation sphere of four water molecules has shown better accuracy to phenol. For the radical intermediate O1, the most suitable model found was the one with six water molecules joined in a cycle on the hydroxyls bonded to the ring. With the obtained results and their comparisons with experimental data, the applicability of Molecular Modeling techniques in Chemical Engineering studies is discussed, reinforcing the perspective of this tool as an important instrument for the design of new products and the optimization of technologically relevant processes.

Orientador: Bruno Coraucci Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-25T02:14:27Z (GMT). No. of bitstreams: 1 Marques_Adriana_M.pdf: 1587467 bytes, checksum: 87b1eed8c16c15a48054969fddf06d83 (MD5) Previous issue date: 2003 / Resumo: Pesquisas de métodos de desinfecção alternativos à cloração vêm sendo desenvolvidas e dentre elas destacam-se a radiação ultravioleta e os processos oxidativos envolvendo geração do radical hidroxila ·OH, por meio da fotólise com uso do peróxido de hidrogênio, as quais foram investigadas neste trabalho. Utilizou-se um fotoreator linear com uma lâmpada germicida e o efluente foi bombeado com fluxo contínuo por meio de passagem única e coletado na saída para as análises físicas químicas e bacteriológicas. Os micro-organismos indicadores foram coliformes totais e fecais provenientes dos efluentes da lagoa anaeróbia. Os parâmetros monitorados nos ensaios fotoliticos e nos ensaios de mistura completa do peróxido de hidrogênio foram cor, turbidez, alcalinidade, sólidos em suspensão, pH e DQO. Os parâmetros de controle de desinfecção UV e UV/H2O2 foram a dose de radiação UV, carga bacteriana pré e pós - desinfecção, tempo de contato e volume e concentração do peróxido de hidrogênio. Os resultados demonstraram que os processos apresentaram eficiência de desinfecção bastantes significativos. No processo utilizando H2O2 com dose de 10 mg/L e tempo de contato de 45 minutos, atingui-se remoções significantes mas não totais de E.coli e coliformes fecais; enquanto que no processo fotolítico com dose de cerca de 25 mW.s/cm2 combinado com o H2O2 a remoção alcançou 99,99% para o referido parâmetro. O processo UV/H2O2 demonstrou ser o mais eficiente em comparação a UV e H2O2 permite a diminuição do volume utilizado de peróxido e do tempo de contato para uma dose de UV relativamente baixa variando de 20 a 35 mW.s/cm2 obtendo uma remoção superior a 4 ordens de magnitude / Abstract: Some alternative disinfection methods to chlorination have been developing recently, and among these, the UV irradiation and oxidation processes involving generation of OH. The use of hydrogen peroxide (H2O2), had deserved special attention, and were investigated in this work. For this purpose, it was utilized inline UV-reator with a germicide lamp. The effluent was mixed with hydrogen peroxide and was conducted through the channel of the reactor by a continue flow. The faecal micro-organisms E.coli and total coliformes were utilized as a pollution indicator combed through the entrance by a continue flow the process to be analysed. The parameters monitored in these process were colour, turbidity, alkalinity, COD and faecal coliformes. The control parameters of UV and H2O2. The results shown that both disinfection processes were efficient for anaerobic lagoon treatment. In the H2O2 process with 10 mg/L and 45 minutes. It was necessary to remove of 3 orders of magnitude faecal and total coliformes. The results shown also that the combined processes are more efficient in the microorganisms inactivation, and whereas for the low doses as 20-35 mWs/cm2 are able to remove 4 magnitude orders remove 4 orders of magnitude / Mestrado / Saneamento e Ambiente / Mestra em Engenharia Civil

Orientador: José Roberto Guimarães / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-19T19:11:27Z (GMT). No. of bitstreams: 1 Barbosa_IzabelaMajor_M.pdf: 2150780 bytes, checksum: 874939a28cdf8546758349402fb228e2 (MD5) Previous issue date: 2012 / Resumo: A abamectina é uma avermectina amplamente utilizada como antiparasitário na pecuária. Os processos selecionados para degradação do fármaco veterinário foram fotólise (UV), peroxidação (H2O2), peroxidação assistida por luz ultravioleta (UV/H2O2), reagente de Fenton e foto-Fenton. A concentração inicial de abamectina foi de 500 ?g L-1 e cada ensaio teve duração de 600 segundos... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Abamectin is widely used as a pest control in livestock. Photolysis (UV), peroxidation (H2O2), peroxidation assisted by ultraviolet light (UV/H2O2), Fenton's reagent and photo- Fenton were selected for the degradation of this veterinary drug. The initial concentration of abamectin was 500 ?g L-1 and each test was carried out during 600 seconds....Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil

Orientador: José Roberto Guimarães / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-21T02:45:49Z (GMT). No. of bitstreams: 1 DalBosco_SandraMaria_D.pdf: 1640850 bytes, checksum: 320db8502d6cebf6f31820fec9e7739d (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foi avaliada a degradação de ivermectina em solução aquosa (500 ?g L-1) pelos processos de peroxidação, fotólise, peroxidação assistida por luz ultravioleta, reagente de Fenton, foto-Fenton, fotocatálise com TiO2 em suspensão, eletroquímico e fotoeletroquímico. A peroxidação foi ineficaz independentemente da concentração de H2O2 utilizada (0,5 - 10 mmol L-1). A fotólise e a peroxidação assistida por luz ultravioleta apresentaram eficiências superiores a 98% em 300 s de reação (dose de 1.410 mJ cm-2). No processo de degradação Fenton, quando utilizado 1,0 mmol L-1de Fe(II) e 5,0 mmol L-1 de H2O2, a eficiência máxima foi de 80% em 60 s. No foto-Fenton as degradações atingiram 99 % em 600 s de reação. Na fotocatálise com TiO2 em suspensão houve uma degradação de 90% para uma dose de radiação de 1.410 mJ cm-2, e 97% para 2.820 mJ cm-2. No processo eletroquímico em 60 s de reação a eficiência foi entre 50 e 60%, e em 600 s entre 60 e 70% em todas as condições de densidade de corrente elétrica (13,6 a 40,9 mA cm-2) e concentrações de eletrólito suporte (0,01 a 0,25 mmol L-1 de K2SO4) avaliadas. O processo fotoeletroquímico apresentou eficiência de degradação próxima a 95% em 300 s de reação, independentemente das concentrações de eletrólito suporte e densidades de corrente elétrica empregadas. De forma geral, as reduções da toxicidade aguda, utilizando-se o microcrustáceo Daphnia similis como organismo-teste, foram diretamente proporcionais às eficiências de degradação. Ao final de 600 s não foi observada toxicidade nas soluções submetidas aos processos de fotólise, peroxidação assistida por luz ultravioleta, reagente de Fenton (1,0 e 5,0 mmol L-1 de Fe(II) e H2O2, respectivamente), foto-Fenton (todas as condições avaliadas) e fotocatálise com TiO2/H2O2 (0,12 e 0,01 mmol L-1 de TiO2 e H2O2, respectivamente) / Abstract: Ivermectin degradation (500 ?g L-1) by peroxidation, photolysis, peroxidation assisted by UV radiation, Fenton's reagent, photo-Fenton, photocatalysis with TiO2 in suspension, electrochemical, and photoelectrochemical processes were evaluated. Peroxidation was ineffective regardless of H2O2 concentration used (0.5 - 10 mmol L-1). The photolysis and peroxidation assisted by UV radiation reached 98% of degradation in 300 s of reaction (dose of 1410 mJ cm -2). The maximum efficiency in Fenton process was 80% for 60 s (1.0 mmol L-1 Fe(II) and 5.0 mmol L-1 H2O2. For photo-Fenton the degradation efficiency reached 99% in 600 s reaction. In photocatalysis assays the degradation was 90% for a radiation dose of 1410 mJ cm-2 and 97% for 2820 mJ cm-2. In the electrochemical process the efficiency ranged from 50% to 60% in 60 s of reaction and from 60% to 70% in 600 s when the current density ranged from 13.6 to 40.9 mA cm-2 (supporting electrolyte concentration of 0.01 and 0.25 mmol L-1). The photoelectrochemical process presented 95% of degradation efficiency in 300 s of reaction, regardless of the electrolyte concentrations and electrical current densities employed. In general, the acute toxicity reductions using the micro-organism Daphnia similis as organism-test were directly proportional to the efficiencies of degradation. In 600 s of the reaction, no toxicity was observed in the solution submitted to photolysis, peroxidation assisted by UV radiation, Fenton's reagent (1.0 mmol L-1 of Fe(II) and 5.0 mmol L-1 of H2O2), photo-Fenton (all conditions studied), and photocatalysis with TiO2/H2O2 (0.12 and 0.01 mmol L-1 of TiO2 and H2O2, respectively) processes / Doutorado / Saneamento e Ambiente / Doutora em Engenharia Civil

Due to their potential health impact on human beings and ecosystems, persistent trace organic compounds (TOrCs) have aroused concern from both the public and professionals. In particular, the discharge of pharmaceuticals, endocrine disrupters, disinfection byproducts and other TOrCs from wastewater treatment plants into the environment is an area of extensive current research. This work studies the fate and treatments of TOrCs, with emphases on advanced oxidation processes (AOPs). This work presents predicted removal efficiencies of a variety of engineered and natural processes for 55 frequently encountered TOrCs in treated wastewater, based on previously reported data and using existing predictive models. Correlations between physicochemical and biological properties of TOrCs and treatment performance were explored. Removal of TOrCs in all processes investigated in this study was found to be sensitive to matrix effects. Heuristic guidelines for selection of sequenced treatment processes for TOrCs management were established. A field reconnaissance of natural process of TOrCs was conducted by analyzing the occurrence and fate of a suite of TOrCs, as well as estrogenic activity in water and sediments in the Santa Cruz River, an effluent-dependent stream in Tucson, Arizona. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. TOrCs that have low biodegradability and low octanolwater partitioning coefficients were less removed. Results of independent experiments indicated potential indirect photodegradation of estrogenic compound by reactive species generated from photolysis of effluent organic matter. Utilizing advanced oxidation processes (AOPs) as tertiary water and wastewater treatment is an option to prevent discharge of TOrCs into the environment. Compared to conventional AOPs, the ability of generating hydroxyl radicals (•OH) without additional doses of hydrogen peroxide (H2O2) or ozone makes ultraviolet (UV) photolysis of ferric hydroxo complexes a novel AOP, especially in acidic environments. A Fe(III)/UV254 kinetic model, which combines Fenton-like mechanism, and photolyses of Fe3+, FeOH2+ and H2O2 was proposed and experimentally validated to predict Fenton-like and H2O2 direct UV254 photolysis scenarios, individually. Nevertheless, the model underestimated the ferrous ion development during Fe(III)/UV254 photolysis, perhaps due to the overprediction of the oxidation of Fe2+ by •OH. The UV/H2O2 AOP was also studied in this work. A predictive kinetic model was developed to evaluate process efficiency of oxidation of p-cresol by UV/H2O2 photolysis based on a complete reaction mechanism, including reactions of intermediates with •OH. Results of this study highlight the significance of consideration of radical scavenging effects by the byproducts from oxidation of organic matter in model prediction performance.

Os poluentes orgânicos emergentes (POE) são compostos químicos presentes numa variedade de produtos comerciais como medicamentos, produtos de higiene, agrotóxicos, surfactantes, dentre outros, podendo ser encontrados em matrizes ambientais e biológicas. Esses poluentes não são usualmente monitorados ou ainda não possuem legislação regulatória correspondente, mas apresentam risco à saúde humana e ao meio ambiente. Dentre esses POE, podemos destacar o nonilfenol etoxilado, um surfactante não-iônico utilizado no desengraxe alcalino da indústria de galvanoplastia. Esse surfactante possui uma recalcitrância e toxidade que aumenta com a diminuição do número de grupos etoxilados, processo que ocorre quando ele é biodegradado. Alguns dos produtos da biodegradação são o nonilfenol com 4, 3, 2 ou 1 grau de etoxilação e nonilfenol, este considerado disruptor endócrino imitando o hormônio natural 17β-estradiol. Tratamentos convencionais de efluentes e água não são eficientes para degradação completa desses compostos. O emprego de processos mais eficientes, como processos oxidativos e oxidativos avançados tais como a Eletrólise (E), Fotólise direta (F), Fotocatálise heterogênea (FH) e a fotoeletrooxidação (FEO), tecnologias limpas que utilizam o elétron e o fóton como reagentes, têm sido proposto como opção para a degradação desses compostos, evitando assim a contaminação dos recursos hídricos. Este trabalho foi realizado com uma solução baseada na composição de um efluente industrial contendo nonilfenol etoxilado com 4 graus de etoxilação. Os ensaios de FEO foram realizados em triplicata, variando-se a densidade de corrente, potência de lâmpada e o tempo de tratamento. Além disso, foram realizados, para efeito de comparação e elucidação de mecanismos, ensaios de eletrólise, fotólise direta e fotocatálise heterogêna. As amostras coletadas antes e após os processos oxidativos foram caracterizadas por diferentes métodos analíticos e por toxicidade. Verificou-se que no tempo de tratamento de 240 minutos as diferentes configurações de FEO não foram suficientemente eficazes na degradação de todo o poluente que se encontra na solução inicial, entretanto, a configuração FEO3 não gerou metabólitos mais tóxicos, não apresentou diferença de germinação e de crescimento de raiz, não apresentando também citotoxicidade e genotoxicidade em alface e em cebola, apresentando toxicidade apenas em peixes em uma concentração de 70,71%, o que pode ser evitado com o aumentando do tempo de tratamento, à vista disso, o processo de FEO torna-se uma opção na degradação do nonilfenol etoxilado e de outros POE, evitando assim que esses atinjam os recursos hídricos. / The emerging organic pollutants (POE) are chemical compounds present in a variety of commercial products such as medicines, toiletries, pesticides, surfactants, among others, can be found in environmental and biological matrices. These pollutants are usually not monitored or have no corresponding regulatory legislation, but present risk to human health and the environment. POE Among these, we highlight the nonylphenol ethoxylate, one non-ionic surfactant used in degreasing alkaline electroplating industry. This surfactant has a recalcitrance and toxicity increases with the decrease of the number of ethoxylate groups, a process which occurs when it is biodegraded. Some of the products of biodegradation are nonylphenol with 4, 3, 2 or 1 degree of ethoxylation of nonylphenol and this considered endocrine disruptor mimicking the natural hormone 17β -estradiol. Conventional treatment of sewage and water are not efficient for complete degradation of these compounds. The use of more efficient processes, such as oxidation and advanced oxidation processes such as direct photolysis (F), Electrolysis (E), heterogeneous photocatalysis (FH) and photoelectrooxidation (FEO), clean technologies that utilize the electron and photon reagents have been proposed as an option to the degradation of such compounds, thereby avoiding the contamination of water resources. This work was carried out with a solution based on the composition of an industrial effluent containing nonylphenol ethoxylate with 4 degrees of ethoxylation. FEO assays were performed in triplicate, by varying the current density lamp power and treatment time. In addition, we performed, for comparison and elucidation of mechanisms, testing electrolysis, photolysis and photocatalysis heterogenous. The samples collected before and after the oxidative processes were characterized by different analytical methods and toxicity. It was found that treatment time of 240 minutes, the FEO different configurations were not efficient enough to degrade any pollutants that is in the initial solution, however, the configuration FEO3 not more toxic metabolites generated no significant difference in seed germination and root growth, no significant cytotoxicity and genotoxicity also in lettuce and onion, showing toxicity on fish only at a concentration of 70.71 %, which can be avoided by increasing treatment time, the sight, the process of FEO becomes an option in the degradation of nonylphenol ethoxylate and other POE, thus preventing it reaches the water.

En las últimas décadas, los procesos redox fotoinducidos mediados por luz visible han recibido gran atención debido a las suaves condiciones de operación en que se llevan a cabo. Como resultado, se han logrado posicionar como una alternativa más dentro de los Procesos de Oxidación Avanzada. Además, se han convertido en una metodología excepcional en síntesis orgánica, que ha abierto la puerta a nuevas rutas químicas con aplicaciones sintéticas. Sin embargo, a pesar del crecimiento del campo, se ha prestado poca atención a los mecanismos por los que operan estos procesos. El principal objetivo de esta tesis fue avanzar en la comprensión de distintos procesos fotoredox llevados a cabo empleando fotocatalizadores orgánicos. Más específicamente, se estudió la viabilidad de distintos fotocatalizadores orgánicos, y además, se realizó un estudio mecanístico detallado basado en técnicas resueltas en el tiempo. A partir de estos resultados, se estableció una metodología para determinar los puntos clave a considerar en un sistema fotoredox. En primer lugar, en la Parte I, se eligieron dos fotocatalizadores basados en sales de pirilio y tiapirilio, que operan mediante transferencia electrónica oxidativa, con distintos objetivos. En el Capítulo 3, se evaluó su aplicabilidad en la fotodegradación de dos contaminantes de la industria del corcho y se estudió el mecanismo por el que se produce dicha fotodegradación. En el Capítulo 4, se demostró la utilidad de la detección directa de todos los intermedios de vida corta derivados del TPP+ implicados en la oxidación fotocatalizada como herramienta para evaluar el nivel de fotodegradación. En el Capítulo 5, se empleó TPTP+ para establecer las mejores características de un fotocatalizador y la influencia de la concentración de las sustancias a oxidar en la eficiencia de los estados excitados, o en general, de los intermedios clave de vida corta. En segundo lugar, en la Parte II, en el Capítulo 6, se evaluó el potencial del Rosa Bengala en la eliminación de dos fármacos. Éste es un fotocatalizador típico en la remediación de aguas residuales conocido por actuar via mecanismo Tipo II. Se incluyó además un segundo fotocatalizador, Perinaftenona, cuyo rendimiento cuántico de oxígeno singlete es incluso mayor a Rosa Bengala. En el Capítulo 7, se llevó a cabo la fotooxidación de tres contaminantes, usando NMQ+, un fotocatalizador inusual, capaz de generar oxígeno singlete desde su estado excitado singlete. En todos los casos se pudo demostrar la mayor contribución del mecanismo Tipo I sobre el mecanismo Tipo II en la fotodegradación de los diferentes contaminantes. Finalmente, en la Parte II, el Capítulo 8 se dedicó a la reducción fotocatalítica de bromuros orgánicos, empleando Riboflavina, un colorante orgánico no metálico, como fotocatalizador. De nuevo, se prestó especial atención a la detección y comportamiento de las especies intermedias, lo que resultó de acuerdo a los datos termodinámicos. / En les últimes dècades, els processos redox fotoinduïts mitjan per llum visible han rebut gran atenció degut a les suaus condicions d'operació en que es donen. Com a resultat, s'han aconseguit col·locar com una alternativa mes dins dels Processos d'Oxidació Avançada. A més, han estat convertint-se en una metodologia excepcional en síntesi orgànica, que ha obert la porta a noves rutes químiques amb aplicacions sintètiques. No obstant això, a pesar del creixement del camp, s'ha prestat poca atenció als mecanismes pels que operen aquests processos. El principal objectiu d'esta tesi va ser avançar en la comprensió de diferents processos fotoredox duts a terme emprant fotocatalitzadors orgànics. Més específicament, es va estudiar la viabilitat de distints fotocatalitzadors orgànics, i a més, es va realitzar un estudi mecanístic al detall basat en tècniques resoltes en el temps. Amb aquests resultats, es va establir una metodologia per a determinar els punts clau a considerar en un sistema fotoredox. En primer lloc, en la Part I, es van elegir dos fotocatalitzadors basats en sals de pirili i tiapirili, els quals operen per mitjà de transferència electrònica oxidativa, amb distints objectius. En el Capítol 3, es va avaluar la seua aplicabilitat en la fotodegradació de dos contaminants de la indústria del suro i es va estudiar el mecanisme pel qual es produeix dita fotodegradació. En el Capítol 4, es va demostrar la utilitat de la detecció directa de tots els intermedis de curt temps de vida derivats del TPP+ implicats en l'oxidació fotocatalitzada com a ferramenta per avaluar el nivell de fotodegradació. En el Capítol 5, es va emprar TPTP+ per a establir les millors característiques d'un fotocatalitzador i l'influencia de la concentració de les substàncies a oxidar en la eficiència dels estats oxidats, o en general, del intermedis claus de vida curta. En segon lloc, en la Part II, en el Capítol 6, es va avaluar el potencial del Rosa Bengala en l'eliminació de dos fàrmacs. Aquest es un fotocatalitzador típic en la remediació d'aigües residuals conegut per actuar via mecanisme Tipus II. Es va incloure a més un segon fotocatalitzador, Perinaftenona, el del qual rendiment quàntic d'oxigen singlet és inclús major a Rosa Bengala. En el Capítol 7, es va dur a terme la fotooxidació de tres contaminants, usant NMQ+, un fotocatalitzador inusual, capaç de generar oxigen singlet des del seu estat excitat singlet. En tots els casos es va poder demostrar la major contribució del mecanisme Tipus I sobre el mecanisme Tipo II en la fotodegradació dels diferents contaminants. Finalment, en la Part II, el Capítol 8 es va dedicar a la reducció fotocatalítica de bromurs orgànics, emprant Riboflavina, un colorant orgànic no metàl·lic, com fotocatalitzador. De nou, es va prestar especial atenció a la detecció i comportament de les espècies intermèdies, el que va resultar d'acord amb les dades termodinàmiques. / In the last decades, photoinduced-redox processes mediated through visible light have obtained great attention due to the generally mild operating conditions that they offer. As a result, they constitute a further alternative within the so-called Advanced Oxidation processes. Besides, they are becoming an outstanding methodology in organic synthesis, which has opened the door to new synthetic and chemical routes. However, despite the growth of the field, little attention has been paid to the mechanisms pathways behind these processes. The main objective of this thesis was to gain deeper understanding of different photoredox processes carried out using organic photocatalysts. More specifically, the viability of several organic photocatalysts was studied, and besides, a careful mechanistic study based on time resolved techniques supported the postulated mechanisms. With this information, a methodology determining the key points to consider in a photoredox system were stablished. Firstly, in Part I, two photocatalysts based on pyrilium and thiapyrilium salts, which operate through an oxidative electron transfer, have been used with different objectives. In Chapter 3, the viability of the photodegradation of two common pollutants from cork industry and the mechanism behind it has been evaluated. In Chapter 4, the direct detection of all the TPP+ derived short-lived intermediates in the photocatalyzed oxidation of a mixture of pollutants using TPP+ was proposed as a methodology to assess the photodegradation extent. In the last chapter of Part I, Chapter 5, TPTP+ is used to stablish the best characteristics of a photocatalyst. Besides, the study claimed the influence of the concentration of the target substances in the efficiency of the excited states or, in general, of the key short-lived intermediates. Secondly, in Part II, in Chapter 6, Rose Bengal, a typical photocatalyst used in wastewater remediation, known for working via Type II mechanism, was evaluated for the removal of two common drugs. In addition, a second one, Perinaphtenone, which exhibits even a higher singlet oxygen quantum yield than Rose Bengal was tested. In Chapter 7, NMQ+, a non-typical photocatalyst able of generate singlet oxygen from its singlet excited state, was used in the photooxidation of three different pollutants. In every case, the major contribution of Type I vs Type II mechanism was demonstrated. Finally, in Part III, Chapter 8 was devoted to the photocatalytic reduction of organic bromides. In this case, Riboflavine, a non-metallic organic dye, was used as a photocatalyst. Analogously, careful attention was paid to the behavoiur of the intermediates, which were in agreement, as well as to the thermodynamics of the steps involved in the photocatalytic cycle. / Martínez Haya, R. (2018). Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/114828 / TESIS

With a growing population and continuous accumulation of pollutants, water resources worldwide are quickly being depleted. Drastic improvements need to be made in both water conservation and treatment. Advanced oxidation processes (AOPs) have been developed to go above and beyond the capabilities of traditional wastewater treatment facilities to eliminate emerging contaminants from our water systems. AOPs increase the generation of hydroxyl radicals (•OH) in oxidation reactions, which are less selective and more reactive than other oxidants, such as ozone, so they are more effective at degrading persistent compounds. This study explored an AOP that utilizes ozonated multi-walled carbon nanotubes (MWCNTs) to generate •OH; past research has proven the success of this method of water treatment, showing a significant decrease in the effluent concentration of the tested compounds. However, these previous studies used a batch system with an initial aliquot of ozone, which would not be a feasible option in a commercial application. This research compares results from a semi-batch system with a continuous injection of ozone to these previous batch system studies to determine if continuous ozonation improves •OH generation capability, contaminant degradation, and the associated reaction kinetics. Results from batch studies had shown limitations to both •OH generation and contaminant degradation which were suspected to be due to ozone degradation; however, these results suggest that ozone availability is in fact not a limiting factor to •OH or contaminant degradation, and another mechanism must be at play. Further, to advance the AOP toward a commercially feasible design, a continuous flow-through system with a MWCNT embedded membrane was explored. The continuous system achieved 80% contaminant degradation in some cases, however, with varying retention times and efficiencies over time, the results were inconclusive and additional experimentation is required.

In the master’s thesis are expleined and described proceses and terms related by problematic degradation of pesticides using advenced oxidation proceses and their possibilities of determinations. The essence of the experimental work was development and validate created method for determination of chosen pesticides. Degradation of this pesticides by advenced oxidation proceses and their determination after degradation. The aim of the work was compare chosen oxidation methods and summary of results for designe of the most appropriate method.

In Sweden, the dominating source for emissions of degradable organic substances to water is the pulp and paper industry. The organic substances increase oxygen consumption in the recipient which subsequently threatens aquatic species. Improved process engineering, process closures and use of external treatments have in recent years drastically lowered the Biological Oxygen Demand (BOD). However, the Chemical Oxygen Demand (COD) has not been reduced to the same extent, as some organic substances are more persistent and must be treated with more advanced techniques. Chemical precipitation, which can bind large parts of the remaining COD into solid matter, making it possible to be removed from the effluent by various separation technologies, contributes to an efficient COD removal. However, the direct operating cost for the treatment is high as large amount of chemicals are used in the process, and large quantities of sludge generated. In the near future EU pulp and paper industry will have to meet new regulatory demands on COD discharges, and pulp mills in Asia, South-America and Oceania will meet stringent discharge demands. It is therefore of interest to review alternative treatments in regards to technical, environmental and economical feasibility in the treatment of pulp and paper mill wastewaters. Much interest has been shown for Advanced Oxidation Processes (AOP), which is why these techniques have been evaluated in this thesis. The first part of the report consists of a literature review where processes with the following oxidants have been reviewed: 1. Ozone (O3); 2. Ozone + Hydrogen peroxide (O3/H2O2); 3. Fenton’s reagent (Fe2+/ H2O2); 4. Ozone + Ultraviolet light (O3/UV); 5. Hydrogen peroxide + Ultraviolet light (H2O2/UV); 6. Photo-Fenton’s reagent (Fe2+/ H2O2/UV); 7. Titanium dioxide + Ultraviolet light (TiO2/UV). Ozone treatment (1) and ozone in combination with hydrogen peroxide (2) were chosen for further experimental studies. The experiments were conducted at Wedecos (Xylem Water Solutions) laboratory in Germany and tested on wastewater from three different Swedish mills: A, B and C. The experimental results indicate that treatment with ozone is an efficient method for elimination of COD from pulp and paper mill wastewaters. A relatively high COD reduction (41 % for Mill A, 31% for Mill B and 53% for Mill C) was achieved for all wastewaters with an applied ozone dosage of 0.2g O3/L, without an appreciable impact on other parameters such as pH, N-tot, NO2-, NO3-, NH4+, P-tot and PO43-. There are indications that the nature of the wastewater has an impact on the COD removal efficiency and that TMP wastewater is easier to oxidize in comparison to wastewater from sulphate mills. The combination with hydrogen peroxide did not show any further COD reduction compared to ozone treatment alone, thus confirming the results Ko et al. showed in their study in 2009. Oxidation with ozone is seen as more environmental alternative in comparison to chemical treatment (precipitation/flocculation) because contaminants in the wastewater are destructed rather than concentrated or transferred into a different phase, which leads to the decrease of COD, colour and toxicity without the need to handle large amounts of sludge. However, a subsequent biological treatment may be necessary for removal of BOD as a BOD increase is registered for all wastewater treated in this study. The costs are on the other hand higher in comparison to chemical treatment even though there are indications of cases when treatment with ozone can be profitable (e.g. if the cost for sludge handling increases in the future, price for chemicals increases and electricity price decreases). There are some uncertainties regarding the system and there is no clear evidence that toxic by-products are not formed. More research must be done and more full-scale installations must be reported before the pulp and paper industry is willing to invest in oxidation technology. / I Sverige, är massa- och pappersindustrin den dominerande utsläppskällan av nedbrytbart organiskt material till vatten. När det organiska materialet når recipienten ökar syreförbrukningen eftersom stora mängder syre erfordras för nedbrytningen av materialet. Detta leder i sin tur till att de vattenlevande organismerna hotas och utsätts för syrebrist. Förbättrad processteknik, ökad processlutning och utbyggnad av extern avloppsvattenrening har under de senaste åren drastiskt sänkt den biokemiska syreförbrukningen (BOD). Däremot har den kemiska syreförbrukningen (COD) inte reducerats i samma utsträckning då delar av det organiska materialet är mer persistent och måste behandlas med mer avancerad teknik. Kemisk fällning kan idag binda stora delar av det kvarvarande COD till fast material som sedan kan avlägsnas via olika separationsmetoder. En stor nackdel med den här typen av rening är att stora mängder kemikalier används som i sin tur genererar stora mängder slam som måste tas om hand, vilket introducerar höga driftkostnader. Inom en snar framtid kommer massa- och pappersbruk inom EU att möta nya regulatoriska krav för COD utsläpp, och bruk i Asien, Sydamerika och Oceanien kommer även de att möta väldigt hårda utsläppskrav. Det är därför av intresse att granska alternativa reningsmetoder och utvärdera dess tekniska, miljömässiga och ekonomiska genomförbarhet vid behandling av avloppsvatten från massa- och pappersbruk. Mycket intresse har visats för Avancerade Oxidationsprocesser (AOP), varför dessa tekniker valts att utvärderas i detta examensarbete. Första delen av rapporten innefattar en litteraturstudie där processer med följande oxidanter studerats: 1. Ozon (O3); 2. Ozon + Väteperoxid (O3/H2O2); 3. Fenton’s reagens (Fe2+/ H2O2); 4. Ozon + Ultraviolett ljus (O3/UV); 5. Väteperoxid + Ultraviolett ljus (H2O2/UV); 6. Foto-Fenton’s reagens (Fe2+/ H2O2/UV); 7. Titaniumdioxid + Ultraviolett ljus (TiO2/UV). Utav dessa valdes ozon behandling (1) och ozon i kombination med väteperoxid (2) för vidare experimentella studier. Behandlingarna har utförts vid Wedecos (Xylem Water Solutions) laboratorium i Tyskland och undersökts på avloppsvatten från tre olika svenska bruk; A , B och C. Experimentella resultat tyder på att ozonering är effektiv behandlingsmetod för reducering av COD i avloppsvatten från massa- och pappersbruk. En relativt hög COD reducering (41% för bruk A, 31% för bruk B, och 53% för bruk C)  uppvisades för samtliga avloppsvatten med en tillämpad ozondosering på 0.2 g O3/L, utan någon märkbar inverkan på andra parametrar så som pH, N-tot, NO2-, NO3-, NH4+, P-tot och PO43-. Det förekommer indikationer om att typ av avloppsvatten har en inverkan på COD reduktionen och att TMP avloppsvatten är lättare att oxidera i jämförelse mot avloppsvatten från sulfatmassabruk. Kombinationen av ozon och väteperoxid uppvisade ingen ytterligare COD reduktion i jämförelse mot ozon som enda oxidant, och bekräftade därmed de resultat Ko et al. uppvisade i sin studie 2009. Ozonering ses som ett miljövänligare alternativ till kemisk rening (fällning/flockning) eftersom föroreningarna i vattnet destrueras istället för att koncentreras, vilket innebär att COD, färg och toxicitet kan minskas utan att stora mängder slam genereras. Dock kan en efterföljande biologisk behandling vara nödvändig för avskiljning av BOD då en BOD ökning uppvisats för samtliga avloppsvatten i denna studie i takt med att COD brutits ned till lättnedbrytbart biologisk material. Kostnaderna är däremot höga i jämförelse mot kemisk fällning även om det förekommer indikationer på fall när behandlingen kan vara lönsam (t ex om slamhanteringskostnaderna blir högre i framtiden, inköpspriset för kemikalier ökar och elpriset sjunker). Det råder vissa tveksamheter gällande systemet och det finns inga konkreta bevis på att toxiska biprodukter inte bildas. Mer forskning måste utföras och fler fullskaliga installationer måste rapporteras och innan massa- och pappersindustrin är villig att investera i oxidationstekniken.