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[Abstract] With the aim to build a simple alert system that may be of extended use, a screening for contaminants of emerging concern (CECs) is carried out in the Mero-Barcés hydrographic watershed, in Cecebre, A Coruña, NW Spain, which feeds the reservoir that supplies drinking water to ≈400 000 inhabitants in the area. Water samples are collected for five years (2015–2019) at six different sampling points, to assess the presence and potential risk of CECs, including some widely used drugs: clofibric acid, paracetamol carbamazepine, diclofenac, ibuprofen, ofloxacin, ketoprofen, and sotalol; an alkaloid: caffeine; synthetic flavourings: galaxolide and tonalide; and a plasticiser: bisphenol A. The most abundant CECs occurring are ibuprofen (>2µg L−1), diclofenac, caffeine, and galaxolide. Samples of treated drinking water show a certain degree of CECs abatement. The presence of nonpolar substances, banned in the EU nowadays, is confirmed. A snapshot of sediments is sampled in 2018–2019, and PAHs and PCBs are quantified, the former being mainly of pyrogenic origin. Based on known properties of quantifiable substances, a traffic-light system is developed for risk assessment of the state of continental waters, a strategy that may be useful for decission-makers to implement environmental remediation policies

[Resumen] La evolución del arte ha ido de la mano de la evolución científica y tecnológica. Algunos materiales y técnicas han propiciado el sugimiento de nuevos movimientos artísticos, y algunos materiales y técnicas se han desarrollado para satisfacer las demandas de los artistas. Los artistas se sirven de las herramientas que la ciencia y la tecnología les proporcionan no sólo por sus cualidades plásticas, sino como parte del código de comunicación (una escultura de bronce no significa lo mismo que una de acero o de madera). Especialmente en el arte moderno y contemporáneo los materiales tienen una importante carga simbólica, que se estudia desde la semiótica, para cuya comprensión sería pertinente contar con conocimientos científicos, sobre todo de química. La visión de la semiótica del arte moderno y contemporáneo desde el prisma de la ciencia es la aportación más innovadora y original de esta investigación. Los resultados de esta investigación acerca de los vínculos entre la ciencia y el arte se han empleado como estrategia de divulgación científica y como una forma exitosa de abordaje multidisciplinar de la cultura científica., [Resumo] A evolución da arte foi acompañada da evolución científica e tecnolóxica. Algúns materiais e técnicas orixinaron novos movementos artísticos, e algúns materiais e técnicas desenvolvéronse para satisfacer as demandas dos artistas. Os artistas fan uso das ferramentas que a ciencia e a tecnoloxía lles proporcionan non só polas súas calidades plásticas, senón tamén como parte do código de comunicación (unha escultura de bronce non significa o mesmo que unha escultura de aceiro ou madeira). Sobre todo na arte moderna e contemporánea, os materiais teñen unha importante carga simbólica, que se estuda desde a semiótica, para cuxa comprensión sería pertinente contar cun coñecemento científico, sobre todo da química. A visión da semiótica da arte moderna e contemporánea desde o prisma da ciencia é a achega máis innovadora e orixinal desta investigación. Os resultados desta investigación sobre os vínculos entre a ciencia e a arte utilizáronse como estratexia de divulgación científica e como unha vía exitosa de achegamento multidisciplinar á cultura científica., [Abstract] The evolution of art has gone hand in hand with scientific and technological evolution. Some materials and techniques have given rise to new artistic movements, and some materials and techniques have been developed to meet the demands of artists. Artists make use of the tools that science and technology provide them with, not only because of their plastic characteristics, but also as part of the communication code (a bronze sculpture does not mean the same when made of steel or made of wood). Materials have an important symbolic charge, very specially in modern and contemporary art, which is part of the study of semiotics, to understand which it would be pertinent to have a proper scientific knowledge, very especially about chemistry. The vision of the semiotics of modern and contemporary art from the point of view of science is the most innovative and original contribution of this research. The results of this research on the links between science and art have been used as a strategy for science dissemination and as a successful way of multidisciplinary approach to scientific culture.

[Resumen] La extracción tradicional de oro y plata, una de las actividades más antiguas del ser humano, está asociada a un nefasto impacto medioambiental. Una alternativa para que el proceso de beneficio se convierta en una actividad más sostenible es la aplicación de la herramienta de Producción más Limpia, que persigue minimizar el uso de recursos naturales no renovables, la generación de contaminantes y los riesgos laborales. PmL se aplicó en la planta de beneficio El Puma, sobre todas las etapas del proceso, utilizando la metodología propuesta por la Organización de las Naciones Unidas para el Desarrollo Industrial, apoyándose en el método de las 5M (Máquina, Método, Mano de obra, Medio ambiente y Materia prima). La actuación sobre diversa maquinaria implicó una mejora en la eficiencia energética y una menor siniestralidad laboral. La reutilización del agua ha implicado su empleo más sostenible, mientras que la potencial reutilización de los relaves convierte este residuo en un recurso. PmL ha implicado una mejora promedio del 12% en eficiencia y en productividad. Por su parte, desde el punto de vista del ingreso operativo se ha producido un incremento del 32.64%, con la previsión de un incremento mayor al 10% en años sucesivos., [Resumo] A extracción tradicional de ouro e prata, unha das actividades máis antigas do ser humano, está asociada a un nefasto impacto ambiental. Unha alternativa para que o proceso de beneficio convértase nunha actividade máis sostible é a aplicación da ferramenta de Produción máis Limpa, que persegue minimizar o uso de recursos naturais non renovables, a xeración de contaminantes e os riscos laborais. PmL aplicouse na planta de beneficio El Puma, sobre todas as etapas do proceso, utilizando a metodoloxía proposta pola Organización das Nacións Unidas para o Desenvolvemento Industrial, apoiándose no método das 5M (Máquina, Método, Man de obra, Medio ambiente e Materia prima). A actuación sobre diversa maquinaria implicou unha mellora na eficiencia enerxética e unha menor sinistralidade laboral. A reutilización da auga implicou o seu emprego máis sostible, mentres que a potencial reutilización dos relaves converte este residuo nun recurso. PmL implicou unha mellora media do 12% en eficiencia e en produtividade. Pola súa banda, desde o punto de vista do ingreso operativo produciuse un incremento do 32.64%, coa previsión dun incremento maior ao 10% en anos sucesivos., [Abstract] Mining is one of the oldest activities of the human being, specifically the extraction of gold, using traditional processes, is associated with a disastrous environmental impact. An alternative for the benefit process to become a more sustainable activity is the application of the Cleaner Production tool, which seeks to minimize the use of non-renewable natural resources, the generation of pollutants and occupational risks. The application of the PmL tool was carried out at the El Puma plant using the United Nations Industrial Development Organization methodology based on the 5M method: Machine, Medium, Method, Material, Workforce. It was necessary to act on all stages of the process. The action on various machinery implied an improvement in energy efficiency as well as a lower occupational accident rate. The reuse of water has implied a more sustainable use of this resource and the potential reuse of tailings turns this residue into a resource. PmL has implied an average improvement of 12% in efficiency and productivity. On the other hand, from the point of view of operating income, there has been an increase of 32.64%, with the forecast of an increase of more than 10% in successive years.

[Resumen] Los procesos de oxidación avanzada (POAs) activados por luz representan una alternativa real y efectiva para la eliminación de compuestos orgánicos y desinfección de aguas contaminadas; por ello, en esta investigación de doctorado se estudian diversos aspectos de los procesos fotoquímicos de degradación de contaminantes e inactivación de microorganismos. Inicialmente, se ha examinado la aplicación y eficiencia de varias técnicas de fotooxidación para la eliminación de dos organismos patógenos presentes en agua de camaroneras. Puesto que muchos productos de transformación de contaminantes resultan más tóxicos que los compuestos originales, también se ha evaluado la toxicidad de dos pesticidas y sus productos de degradación mediante indicadores biológicos. La fotocatálisis heterogénea solar es, probablemente, el método más verde y sostenible para el tratamiento de aguas. Sin embargo, presenta un importante problema: la recuperación del catalizador y su pérdida de eficiencia con el uso; por ello, se ha desarrollado un novedoso fotocatalizador homogéneo que combina semiconductores (óxido de titanio y óxido de zinc) con arcillas, y que permite su sencilla reutilización sin una pérdida significativa de actividad, por lo que se ha solicitado y concedido una patente de invención. Este composite se ha probado bajo radiación solar y artificial para la degradación de distintos contaminantes orgánicos (fenol, naranja de metilo, terbumetón y bromuro de N-hexilpiridinio) y la inactivación de bacterias patógenas (Staphylococcus aureus y Escherichia coli), mostrando una elevada eficacia incluso en matrices acuosas complejas (agua de río, agua residual y agua de mar)., [Resumo] Os procesos de oxidación avanzada (POAs) activados por luz representan unha alternativa real e efectiva para a eliminación de compostos orgánicos e desinfección de augas contaminadas; por iso, nesta investigación de doutoramento estúdanse diversos aspectos dos procesos fotoquímicos de degradación de contaminantes e inactivación de microorganismos. Inicialmente, examinouse a aplicación e eficiencia de varias técnicas de fotoxidación para a eliminación de dous organismos patóxenos presentes en auga de camaroneiras. Posto que moitos produtos de transformación de contaminantes resultan máis tóxicos que os compostos orixinais, tamén se avaliou a toxicidade de dous pesticidas e os seus produtos de degradación mediante indicadores biolóxicos. A fotocatálise heteroxénea solar é, probablemente, o método máis verde e sostible para o tratamento de augas. Con todo, presenta un importante problema: a recuperación do catalizador e a súa perda de eficiencia co uso; por iso, desenvolveuse un novo fotocatalizador homoxéneo que combina semicondutores (óxido de titanio e óxido de zinc) con arxilas, e que permite a súa sinxela reutilización sen unha perda significativa de actividade, polo que se solicitou e concedeu unha patente de invención. Este composite probouse baixo radiación solar e artificial para a degradación de distintos contaminantes orgánicos (fenol, laranxa de metilo, terbumetón e bromuro de Nhexilpiridinio) e a inactivación de bacterias patóxenas (Staphylococcus aureus e Escherichia coli), amosando unha elevada eficacia mesmo en matrices acuosas complexas (auga de río, auga residual e auga de mar)., [Abstract] Light-activated advanced oxidation processes (AOPs) represent a real and effective alternative for the removal of organic compounds and the disinfection of contaminated water; therefore, in this PhD thesis several aspects of the photochemical processes of pollutant degradation and microorganism inactivation are studied. Firstly, the application and efficiency of different photooxidation techniques for the removal of two pathogenic organisms present in shrimp farm water have been investigated. Since many pollutant transformation products are more toxic than the original compounds, the toxicity of two pesticides and their degradation products was also evaluated using biological indicators. Solar heterogeneous photocatalysis is probably the greenest and most sustainable method for water treatment. However, it has a major problem: the recovery of the catalyst and its loss of efficiency with use. For this reason, a new homogeneous photocatalyst has been developed, which combines semiconductors (titanium oxide and zinc oxide) with clays and which can be easily reused without significant loss of activity, for which a patent has been filed and granted. This composite has been tested under solar and artificial radiation for the degradation of several organic pollutants (phenol, methyl orange, terbumeton and Nhexylpyridinium bromide) and the inactivation of pathogenic bacteria (Staphylococcus aureus and Escherichia coli), showing high efficiency even in complex aqueous matrices (river water, wastewater and sea water).

[Abstract] One of the main challenges of photocatalysis is to find a stable and effective photocatalyst, that is active and effective under sunlight. Here, we discuss the photocatalytic degradation of phenol as a model pollutant in aqueous solution using NUV-Vis (>366 nm) and UV (254 nm) in the presence of TiO2-P25 impregnated with different concentrations of Co (0.1%, 0.3%, 0.5%, and 1%). The modification of the surface of the photocatalyst was performed by wet impregnation, and the obtained solids were characterized using X-ray diffraction, XPS, SEM, EDS, TEM, N2 physisorption, Raman and UV-Vis DRS, which revealed the structural and morphological stability of the modified material. BET isotherms are type IV, with slit-shaped pores formed by nonrigid aggregate particles and no pore networks and a small H3 loop near the maximum relative pressure. The doped samples show increased crystallite sizes and a lower band gap, extending visible light harvesting. All prepared catalysts showed band gaps in the interval 2.3–2.5 eV. The photocatalytic degradation of aqueous phenol over TiO2-P25 and Co(X%)/TiO2 was monitored using UV-Vis spectrophotometry: Co(0.1%)/TiO2 being the most effective with NUV-Vis irradiation. TOC analysis showed ca. 96% TOC removal with NUV-Vis radiation, while only 23% removal under UV radiation.

[Abstract] An innovative bulky photocatalyst for water decontamination has been developed. The semiconductor (TiO2) is homogeneously distributed in an aggregating material through the whole piece. This design prevents the activity reduction usually observed in supported catalysts due to the loss of the photoactive layer, and facilitates its recovery for an easy reuse, which is a recurrent problem dealing with nanoparticles. The photocatalyst combines the excellent properties of TiO2 with those of a natural clay, which serves as binder, slows down the phase transition of anatase to rutile upon calcination, and has a synergetic function. The photocatalyst has been prepared in the form of small pellets with an Ecuadorian clay and TiO2 in the commercial form of P25 by evenly dry mixing, forming a paste with water, and subsequent extrusion, drying and calcination at 600 °C. The photodegradation of phenol, as a model pollutant, has been achieved by using this aggregate material in a flow reactor with artificial UVA-Vis radiation, and reused without any significant loss of activity. The photocatalyst showed an optimum activity at a 40% clay / 60% P25 ratio, while higher calcination temperatures had a negative effect on its performance.

[Abstract] This study reports the performance of a three-step lab-scale system including a hybrid digester (HD), a vertical flow (VF) constructed wetland, and a photodegradation (PD) lamp, with two different arrangements regarding the position of the recirculation point. In addition to total suspended solids (TSS), chemical oxygen demand (COD), and nitrogen compounds, removal of the following pollutants was investigated: paracetamol (ACE), ofloxacin (OFL), caffeine (CAF), ketoprofen (KET), ibuprofen (IBU), clofibric acid (ACB), bisphenol A (BPA), and sotalol (SOT). An excellent performance of HD was achieved on the elimination of TSS (82.2 ± 18.5% on average) and COD (63.9 ± 4.1%). TSS and COD removal increased to 91.2 ± 0.4% and 83.4 ± 2.9%, respectively, for the combined HD–VF system. Ammonia removal was 57.0 ± 7.8% in the VF unit while significant denitrification occurred in the HD. The overall HD–VF–PD system achieved mean removals of 100% for OFL, KET, SOT, and IBU, 98 ± 2% for ACE, 87 ± 8% for CAF, 81 ± 38% for ACB and 26 ± 9% for BPA. The removal of ACE, OFL, CAF, and IBU was mostly by biodegradation in the HD and VF units while the PD unit was responsible for the removal of KET, ACB, and SOT.

[Abstract] The behavior of novel pellet-shaped bulky titania-kaolin photocatalysts is herein evaluated for its application in the solar-assisted photocatalytic treatment of a bio-recalcitrant pesticide mix (imidacloprid, pyrimethanil and methomyl) in solar lab-scale and semi-pilot scale raceway pond photoreactors. The photocatalyst consists of 1 cm long titania-kaolin macro-composites that combine some advantages of both nanoparticulate and supported catalysts without being either. This opening the opportunity to extend the use of this photocatalyst to complex wastewater effluents. In addition, their stability and reusability potential was also evaluated, and reactive species leading to the solar-degradation of each pesticide were also identified using radical scavengers. Total removal of pesticides (2 mg L−1 each) with an optimal pellets dosage of 34.8 g L−1 was addressed, whether in ultrapure water (180–270 min of solar irradiation) or in two basic pH Municipal Wastewater Treatment Plant (MWWTP) effluents (≤300 min of solar irradiation) where methomyl was always the most recalcitrant pesticide. Lower Total Organic Carbon (TOC) removal (≈53–56%) was also found under the effect of these complex MWWTP effluents than in ultrapure water (>60%). Those results are very promising when comparing to the almost negligible TOC removal achieved with the Titania powder under basic MWWTP effluents due to the strong effect of particle aggregation. Very good photocatalyst stability and durability was shown along three consecutive cycles after applying a low-cost recovery protocol consisting of several washing and drying cycles without addressing a significant photoefficiency loss (TOC≈60-56%). The application of scavengers revealed that hydroxyl radical generated from photoinduced holes was the dominant species in the degradation of pyrimethanil and methomyl whereas reactive oxygen species formed from conduction band electrons were mainly involved in the photo-oxidation of imidacl

[Abstract] A snapshot screening was carried out in an urban river at the end of a dry period in the water and sediments to assess the presence and environmental risk for the following CECs: paracetamol, ibuprofen, diclofenac, clofibric acid, carbamazepine, ofloxacin, caffeine, tonalide, galaxolide, and bisphenol-A. Concomitantly, the occurrence and environmental risk of sixteen PAHs congeners, six indicator PCBs, and twelve dioxin-like PCBs were evaluated in sediments. The most abundant and ubiquitous CECs were bisphenol A (BPA) and caffeine, and the total contents in the surface water varied between 90.95–212.18 and 3.17–167.38 ng·L−1, respectively. The concentrations found in lixiviates ranged from 134.94–772.85 (BPA) and 14.43–92.60 ng·L−1 (caffeine). Other CECs were detected in lower concentrations, and their presence varied between sampled sites. Values of total PAHs congeners in sediment varied between 10.39–52.91 ng·g−1 dw. The majority of the detected PAHs seem to have a pyrolitic origin with a small petrogenic contribution. Total PCBs’ concentrations ranged from 5.06 to 6.13 ng·g−1 dw. Despite the relatively low concentration of most of the detected compounds, the overall environmental risk, considering the screened compounds altogether, cannot be considered negligible. The obtained results are discussed in terms of other data available (though highly dispersed) in the literature. A four-color alert system is included to inform about the level of risk associated with the amount of each CEC, PAH, and PCB

[Abstract] Alkenes and enol ethers are structures that are frequently found in many biomolecules. When sunlight interacts with them, a photoionization reaction can take place, producing radical cations, which can be harmful for living organisms. In this piece of research electronic properties of ethylene, tetramethylethylene, tetramethoxyethylene and their corresponding radical cations were measured in vacuum and in aqueous solution with computational chemistry models. DFT method with 6-311G as basis set was used to develop the electronic calculations and SMD model was used to simulate water as solvent. Electronic structure calculation software Gaussian and the supercomputer at the supercomputing Galician centre (CESGA) were used to carry out all the calculations. Calculations developed to study the mentioned molecules were: molecular structure optimization from an optimization + frequency calculation, NBO analysis, UV-Vis spectrum and IR + Raman spectrum. Obtained results suggest that radical cation is less stable than the neutral species, and so, more reactive than that, and aqueous solution is able to stabilize it. Ethylene radical cation is the most destabilized followed by TME, in which methyl substituents act as electron donating groups, TMOE is the most stabilized radical cation as oxygen is able to donate a high amount of electronic density to the central carbon atoms of the molecule. A change in the molecule and molecular orbitals symmetry is obtained when shifting from the neutral species to the radical cation. Furthermore, reduction potentials are calculated with the direct method, ionization potentials are estimated with Koopmans´ theorem and spectra analysis is developed., [Resumen] Los alquenos y enol éteres son estructuras que se encuentran con frecuencia en muchas biomoléculas. Cuando la luz solar interactúa con ellos, se puede promover una reacción de fotoionización que conduce a la formación de un radical catión, que puede ser perjudicial para el organismo. En esta investigación se midieron las propiedades electrónicas del etileno, tetrametiletileno, tetrametoxietileno y sus correspondientes radicales cationes en vacío y en disolución acuosa con modelos de química computacional. Se utilizó el método DFT con 6-311G como conjunto base para desarrollar los cálculos electrónicos y el modelo SMD se utilizó para simular el agua como disolvente. Para realizar todos los cálculos se utilizó el software de cálculo de estructuras electrónicas Gaussian y el superordenador del centro gallego de supercomputación (CESGA). Los cálculos que se usaron para estudiar las moléculas mencionadas fueron: optimización de la estructura molecular a partir de un cálculo de optimización + frecuencia, análisis NBO, espectro UV-Vis y espectro IR + Raman. Los resultados obtenidos sugieren que el radical catión es menos estable que la especie neutra, y, por lo tanto, más reactivo que esta, y el medio acuoso es capaz de estabilizarlo. El radical catión del etileno es el más desestabilizado seguido por el del TME, en el que los sustituyentes metilo actúan como grupos donantes de electrones, TMOE es el radical catión más estabilizado ya que el oxígeno es capaz de donar una alta cantidad de densidad electrónica a los átomos de carbono centrales de la molécula. Se obtiene un cambio en la simetría de la molécula y en los orbitales moleculares al pasar de la especie neutra al radical catión. Además, los potenciales de reducción se calculan con el método directo, los potenciales de ionización se estiman con el teorema de Koopman y se desarrolla el análisis de los espectros., [Resumo] Os alquenos e os enol éteres son estruturas que se atopan con frecuencia en moitas biomoléculas. Cando a luz solar interactúa con eles, pódese promover una reacción de fotoionización que conduce á formación dun radical catión, que pode ser prexudicial para o organismo. Nesta investigación medíronse as propiedades electrónicas do etileno, tetrametiletileno, tetrametoxietileno e os seus correspondentes radicais catións en baleiro e en disolución acuosa con modelos de química computacional. Fíxose uso do método DFT con 6-311G como conxunto base para desenvolver os cálculos electrónicos e fíxose uso do modelo SMD para simular o auga como disolvente. Para realizar todos os cálculos utilizouse o software de cálculo de estruturas electrónicas Gaussian e o superordenador do centro galego de supercomputación (CESGA). Os cálculos que se usaron para estudar as moléculas mencionadas foron: optimización da estrutura molecular a partir dun cálculo de optimización + frecuencia, análise NBO, espectro UV-Vis e espectro IR + Raman. Os resultados obtidos suxiren que o radical catión é menos estable que a especie neutra, e, polo tanto, é máis reactivo que esta, ademais o medio acuoso é capaz de estabilizalo. O radical catión do etileno é o máis desestabilizado seguido polo do TME, no que os substituíntes metilo actúan como grupos donantes de electróns, TMOE é o radical catión máis estabilizado xa que o osíxeno é capaz de doar unha alta cantidade de densidade electrónica aos átomos de carbono centrais da molécula. Obtense un cambio na simetría da molécula e nos orbitais moleculares ao pasar da especie neutra ao radical catión. Ademais, os potenciais de redución calcúlanse co método directo, os potenciais de ionización estímanse co teorema de Koopman e desenvólvese o análise dos espectros.

[Abstract] We report on the degradation of aqueous propranolol (PRO) in a heterogeneous system with natural iron oxide (N.I.O.) and oxalic acid (OAA) under near UV–Vis irradiation. Photolysis experiments showed ca. 65% degradation of PRO after 2 h irradiation, and a similar degradation in the presence of N.I.O. A more efficient PRO removal was obtained upon irradiation within a mixture of N.I.O. and OAA. Under the best conditions considered, complete degradation (> 95%) was observed in less than 10 min, and TOC decreased by 60% after 3 h irradiation. The observed processes were adequately fitted by pseudo-first-order kinetics, the corresponding rate constants were determined, and the effect of different variables analyzed. Photodegradation of PRO is accelerated under acidic conditions, and neutralization takes place along the reaction. Hydroxyl radicals play a predominant role in the photodegradation reaction, as shown by the dramatic inhibition observed upon t-butanol addition. Furthermore, HOradical dot formation is strongly dependent on the pH of the medium. LC-MS identification of ten different intermediates leads to the proposal of a degradation mechanism. This photocatalytic system has also proven effective, for the first time, in different real aqueous matrices (river water > distilled water > sewage ≫ > seawater, revealing quite efficient in the former) and also employing sunlight, where PRO photodegradation was slower. The results obtained show that N.I.O.-oxalate complexes are a green, cheap choice for removing organic pollutants in aqueous solution.

[Abstract] Low concentrations of drugs and their metabolites occurring on the aquatic environment are of significant concern due to their potential effects. This work reports on the removal from aqueous solution, of paracetamol or acetaminophen (APAP) as a model pharmaceutical pollutant, promoted by the photo-Fenton system generated by the photolysis of two organic iron(III) complexes, FeIII-Glutamate & FeIII-Lactate, under 365 nm irradiation (2 < pH < 4). UVA photolysis of these complexes is relatively fast: ca.73% of the FeIII-Glu complex decomposed after 1 h of irradiation (t½=6.4 min, pH = 3.40), 91% in the case of FeIII-Lact complex (t½=6.4 min, pH = 3.0). FeIII + Lact system showed a maximum pseudo-first order rate constant at pH ca. 3, while for FeIII + Glu system it increases with pH. NUV irradiation of FeIII-carboxylic acid complexes promotes APAP photodegradation, that is faster with lactate. The maximum pseudo-first order rate constant was observed at pH = 3 for FeIII + Lact + APAP, while it slightly increased with pH for FeIII + Glu + APAP. The rate constant decreases for both systems as APAP concentration increases, likely due to the formation of FeIII-APAP complexes. At t > 180 min, a second, slower, process is observed. Addition of 1% of t-BuOH and anaerobic conditions inhibit APAP photodegradation, which indicates APAP photodegradation in the presence of FeIII-Glu and FeIII-Lact complexes is limited by formation of H2O2, the source of HO. Seven transformation photoproducts were identified by HPLC-MS, mainly hydroxylated derivatives. Reaction pathways are identified, highlighting the role of the photoformed FeIII-carboxylate long-lived radicals, dissolved O2 and HO in the abatement of pollution due to emerging organic contaminants such as APAP.

[Resumen]: Desde el punto de vista bioquímico el selenio forma parte esencial del metabolismo a través de las denominadas selenoproteínas. Estas moléculas presentan una gran importancia en el sistema inmunológico, como defensa antioxidante y en el mantenimiento del estado redox celular. En una sociedad cada vez más concienciada en el cuidado personal, la adquisición de conductas saludables y la preocupación por evitar enfermedades, existen todavía graves problemas que afectan a muchos individuos de nuestra sociedad. Uno de estos problemas es el daño oxidativo o también denominado estrés oxidativo. En los últimos años se han acumulado datos que nos permiten afirmar que los radicales libres y el conjunto de especies reactivas que se les asocian, permiten mantener un equilibrio homeostático en los organismos y participan también en diversos procesos fisiológicos, como, por ejemplo, en la defensa ante agentes infecciosos. Sin embargo, estas moléculas son altamente reactivas y son capaces de dañar a biomoléculas presentes en las células. Una alta concentración de radicales libres en un organismo ocasiona un fenómeno conocido como estrés oxidativo el cual, está asociado a diversas enfermedades. Este incremento de radicales libres puede verse reflejado por la presencia de contaminantes ambientales, del consumo de ciertos alimentos y de sustancias nocivas para el organismo. Los aminoácidos de selenio son una de las respuestas antioxidantes que los organismos presentan para la eliminación de radicales libres y para combatir el estrés oxidativo. Los selenoaminoácidos actúan en la defensa antioxidante a través principalmente de los de la selenometionina y la selenocisteína. Estudios previos han determinado que las reacciones de aminoácidos derivados de selenio con agentes oxidantes son excepcionalmente rápidas en comparación con aminoácidos análogos de azufre. Por lo cual se pretende aportar datos que verifiquen estos estudios. En este trabajo de fin de grado se pretenden dete, [Resumo]: Dende o punto de vista bioquímico o selenio forma unha parte esencial do metabolismo a través das chamadas selenoproteínas. Estas moléculas teñen unha grande importancia no sistema inmunolóxico, como sistema antioxidante e no mantemento do estado redox celular. Nunha sociedade cada vez máis conscente do coidado persoal, a adquisición de conductas saudables e a preocupación por evitar enfermidades, aínda existen graves problemas que afectan a moitos individuos da nosa sociedade. Un destes problemas é o daño oxidativo ou tamén chamado estrés oxidativo. Nos derradeiros anos acumúlanse datos que permiten afirmar que os radicais libres e o conxunto das especies reactivas asociadas a eles, permiten manter o equilibrio homeostático nos organismos e tamén participar nos diversos procesos fisiolóxicos, como, por exemplo, a defensa contra axentes infecciosos. Non obstante, estas moléculas son moi reactivas e son capaces de danar as biomoléculas presentes nas células. Unha alta concentración de radicais libres nun organismo provoca un fenómeno coñecido como estrés oxidativo, asociado a varias enfermidades. O aumento dos radicais libres poden reflectirse pola presenza de contaminantes ambientais, o consumo de certos alimentos e substancias nocivas para o organismo. Os aminoácidos de selenio son unha das respostas antioxidantes que presentan os organismos para a eliminación de radicais libres e para combater o estrés oxidativo. Os selenoaminoácidos actúan na defensa antioxidante principalmente a través da selenometionina e a selenocisteína. Estudos previos determinaron que as reaccións dos aminoácidos derivados do selenio con axentes oxidantes son excepcionalmente rápidas en comparación cos aminoácidos análogos de xofre. Polo tanto, preténdese proporcionar datos para verificar estes estudos. Neste traballo de fin de grao, o obxetivo é determinar cómo actúan estes selenoaminoácidos en reaccións con axentes oxidantes, proporcionando información sobre os seus mecanismo e, [Abstract]: From a biochemical view, selenium forms an essential part of the metabolism through the so-called selenoproteins. These molecules have a great importance in the immune system, as an antioxidant defence and in the maintenance of the cellular redox state. In a society that is becoming increasingly aware of personal care, the acquisition of healthy behaviours and the concern to avoid illnesses, there are still serious problems that affect many individuals in our society. One of these problems is oxidative damage or oxidative stress. In recent years, the data recopilation allow us to affirm that free radicals and the set of reactive species associated with them allow us to maintain a homeostatic balance in organisms and also participate in various physiological processes, such as, for example, in the defence against infectious agents. However, these molecules are highly reactive and are capable of damaging biomolecules present in cells. A high concentration of free radicals in an organism causes a phenomenon known as oxidative stress, which is associated with various diseases. This increase in free radicals can be reflected in the presence of environmental pollutants, the consumption of certain foods and substances harmful to the body. Selenium amino acids are one of the antioxidant responses of organisms to delete free radicals and fight oxidative stress. Selenoamino acids act in the antioxidant defence mainly through the various selenoamino acids. Previous studies have determined that the reactions of selenium-derived amino acids with oxidising agents are exceptionally fast compared to sulphur analogue amino acids. It is therefore intended to provide data to verify these studies. In this thesis, the aim is to determine how these selenoamino acids act in reactions with oxidising agents, providing information on the mechanisms of these reactions and their kinetic properties, as well as analysing factors that may affect these two characteristics.

[Abstract] Myeloperoxidase (MPO) is a myeloid-lineage restricted enzyme largely expressed in the azurophilic granules of neutrophils. It catalyses the formation of reactive oxygen species, mainly hypochlorous acid, contributing to anti-pathogenic defense. Disorders in the production or regulation of MPO may lead to a variety of health conditions, mainly of inflammatory origin, including autoimmune inflammation. We have studied the effect of ionizing radiation on the activity of MPO, as measured by the capacity retained by the enzyme to produce hypochlorous acid as reactive oxygen species after exposure to successive doses of solvated electrons, the strongest possible one-e− reducing agent in water. Chlorination activity was still present after a very high irradiation dose, indicating that radiation damage does not take place at the active site, hindered in the core of MPO structure. Decay kinetics show a dependence on the wavelength, supporting that the process must occur at peripheral functional groups situated on external and readily accessible locations of the enzyme. These results are relevant to understand the mechanism of resistance of our innate anti-pathogenic defense system and also to get insight into potential strategies to regulate MPO levels as a therapeutic target in autoimmune diseases.

[Abstract] Some general features of short-lived intermediates that can be useful when facing mechanistic studies or other projects involving these species are briefly revised, with special attention to properties of neutral radicals, radical cations, radical anions and excited states that condition the fate of the process. Some case studies related to molecules or families of molecules that are of technological relevance are presented: triazine-based radicals, radical cations of enol ethers, aminium and aminyl radicals derived from amino acids. We show how experimental and computational information about short-lived species, their structure and thermodynamic properties, can help control the reactivity and thermodynamics of chemical reactions.