{"id":117903,"date":"2018-03-11T10:47:38","date_gmt":"2018-03-11T10:47:38","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/regeneracion-de-aguas-contaminadas-por-plaguicidas-sustancias-prioritarias-y-preferentes-con-elevado-potencial-de-lixiviacion-mediante-fotocatalisis-solar-heterogenea\/"},"modified":"2018-03-11T10:47:38","modified_gmt":"2018-03-11T10:47:38","slug":"regeneracion-de-aguas-contaminadas-por-plaguicidas-sustancias-prioritarias-y-preferentes-con-elevado-potencial-de-lixiviacion-mediante-fotocatalisis-solar-heterogenea","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/quimica-agricola\/regeneracion-de-aguas-contaminadas-por-plaguicidas-sustancias-prioritarias-y-preferentes-con-elevado-potencial-de-lixiviacion-mediante-fotocatalisis-solar-heterogenea\/","title":{"rendered":"Regeneraci\u00f3n de aguas contaminadas por plaguicidas (sustancias prioritarias y preferentes), con elevado potencial de lixiviaci\u00f3n, mediante fotocat\u00e1lisis solar heterog\u00e9nea."},"content":{"rendered":"<h2>Tesis doctoral de <strong> Jos\u00e9 Angel Escudero Garcia <\/strong><\/h2>\n<p>Resumen la lixiviaci\u00f3n (movimiento del agua y los compuestos disueltos a trav\u00e9s del suelo) de plaguicidas hacia las aguas subterr\u00e1neas, derivada de las pr\u00e1cticas agr\u00edcolas habituales, est\u00e1 recibiendo una atenci\u00f3n creciente en los pa\u00edses europeos, ya que un elevado porcentaje de las mismas se emplea para la obtenci\u00f3n de agua potable. Por esta raz\u00f3n, la ue ha establecido l\u00edmites (0.1 \u00c2\u00b5g l?1 para compuestos individuales y 0.5 \u00c2\u00b5g l?1 para el conjunto de plaguicidas) en agua potable al objeto de salvaguardar la salud de los consumidores y protegerlos de efectos perjudiciales (directiva 2006\/118\/ec). bajo determinadas condiciones, algunos plaguicidas pueden lixiviar hacia las aguas subterr\u00e1neas despu\u00e9s de su aplicaci\u00f3n en campo. En este proceso, intervienen m\u00faltiples factores como las propiedades f\u00edsico-qu\u00edmicas del plaguicida utilizado, los procesos hidrol\u00f3gicos del suelo, as\u00ed como las propiedades del mismo (textura, contenido en arcillas y materia org\u00e1nica y permeabilidad). Sin embargo, entre todos, el contenido en carbono org\u00e1nico (co) es el factor m\u00e1s importante en la adsorci\u00f3n y movilidad en el suelo. Los suelos con bajo contenido en co tienen una capacidad peque\u00f1a para retrasar la movilidad de los plaguicidas ya que, la materia org\u00e1nica (mo) y m\u00e1s concretamente las sustancias h\u00famicas, constituyen el principal adsorbente de los plaguicidas. Actualmente, se est\u00e1 profundizando en el estudio del efecto de los enmendantes org\u00e1nicos (eo) para conocer su influencia en la adsorci\u00f3n y movilidad de los plaguicidas al objeto de minimizar el riesgo de contaminaci\u00f3n asociado con los procesos de lixiviaci\u00f3n y escorrent\u00eda. Sin embargo, los resultados obtenidos indican respuestas contradictorias por los distintos factores implicados. El principal beneficio derivado de la adsorci\u00f3n de los plaguicidas es que, generalmente, se reduce la lixiviaci\u00f3n, aunque su disminuci\u00f3n puede ser debida tambi\u00e9n a otros factores como los cambios estructurales en la porosidad del suelo inducidos por el incremento de mo en el mismo. los plaguicidas pueden contaminar los cuerpos de agua por dos v\u00edas, puntual y difusa. La contaminaci\u00f3n difusa es originada fundamentalmente por la lixiviaci\u00f3n y la infiltraci\u00f3n proveniente de los cauces y las riveras de los r\u00edos. Concretamente, europa tiene grandes problemas derivados de la contaminaci\u00f3n de aguas subterr\u00e1neas, y en donde  la agricultura, es la principal responsable. La mayor\u00eda de los europeos (entre 60-65 %) utiliza el agua subterr\u00e1nea para obtener agua potable. Por lo tanto, es necesario desarrollar y proponer m\u00e9todos para eliminar los plaguicidas en aguas contaminadas sin perjudicar al medio ambiente ni a la salud humana. los m\u00e9todos convencionales de tratamiento de agua ofrecen algunas ventajas como su bajo coste y facilidad de operaci\u00f3n, aunque no suelen ser efectivos para la eliminaci\u00f3n de plaguicidas dada su baja biodegradabilidad. As\u00ed, numerosos estudios han demostrado que los contaminantes pueden ser eliminados del agua mediante procesos avanzados de oxidaci\u00f3n (paos) tales como o3\/uv, h2o2\/uv, h2o2\/o3\/uv, tratamiento foto-fenton y\/o fotocat\u00e1lisis heterog\u00e9nea. Los paos son frequentemente definidos como tratamientos realizados a temperaturas pr\u00f3ximas a la ambiente basados en la producci\u00f3n de radicales hidroxilo (ooh) como oxidante principal, adem\u00e1s de otras especies activas oxigenadas como el radical ani\u00f3n super\u00f3xido (o2o?), Radical hidroperoxilo (ho2o), ox\u00edgeno triplete (3o2), y radical org\u00e1nico peroxilo (rooo). Claramente, el radical ooh (e0= 2.8 v) es una de las especies con mayor poder de oxidaci\u00f3n para el tratamiento de aguas residuales, al acelerar en gran manera la degradaci\u00f3n de los contaminantes presentes en ellas. Entre los paos, la fotocat\u00e1lisis heterog\u00e9nea es un proceso con gran potencial para la eliminaci\u00f3n de plaguicidas en agua, ya que es una t\u00e9cnica de especial inter\u00e9s medioambiental al combinar un coste bajo, condiciones de operaci\u00f3n moderadas y la posibilidad de utilizar la luz solar como fuente de irradiaci\u00f3n. el proceso de fotocat\u00e1lisis solar heterog\u00e9nea emplea las bandas del ultravioleta cercano y visible del espectro solar para fotoexcitar un material semiconductor (sc) en contacto con agua y ox\u00edgeno para generar radicales ooh, poderoso oxidante de naturaleza no espec\u00edfica. As\u00ed, los fotones cuya energ\u00eda sea igual o mayor a la energ\u00eda (eg) correspondiente al ancho de banda del sc (hv ? Eg) pueden ser absorbidos, excitando as\u00ed a los electrones de la banda de Valencia. En consecuencia, se forma un fotohueco con carga positiva (h+) en la banda de Valencia y un fotoelectr\u00f3n (e-) en la banda de conducci\u00f3n (hv + sc ? E- + h+). Los pares e-\/h+ generados act\u00faan como agentes oxidantes y reductores. Simult\u00e1neamente, ocurre un proceso espont\u00e1neo de adsorci\u00f3n de acuerdo con el potencial redox de cada adsorbato, debido a que un electr\u00f3n (e-) se transfiere a la mol\u00e9cula aceptora (a(ads) + e- ? A-(ads)), mientras que un hueco (h+)  lo hace a la donadora (d(ads) + h+ ? D+(ads)). teniendo en cuenta lo anterior, el principal objetivo planteado en este trabajo ha sido evaluar la fotoactividad de tio2 y zno en la degradaci\u00f3n de diferentes plaguicidas, incluidos como sustancias prioritarias por la ue, a nivel de planta piloto bajo irradiaci\u00f3n solar. Previamente, hemos estudiado su potencial de lixiviaci\u00f3n a trav\u00e9s del suelo y optimizado los principales par\u00e1metros del proceso de fotodegradaci\u00f3n (proporci\u00f3n de fases cristalinas, masa de catalizador, adici\u00f3n de aceptores de electrones, ph, intensidad luminosa, concentraci\u00f3n inicial de plaguicida y presencia de sustancias interferentes). los resultados obtenidos indican que, la adici\u00f3n de materia org\u00e1nica ex\u00f3gena (esti\u00e9rcol de oveja compostado, ec; residuos de caf\u00e9, rc; corteza de pino, cp; fibra de coco, fc) a un suelo t\u00edpico de la zona mediterr\u00e1nea (calcisol hiperc\u00e1lcico) con bajo contenido en materia org\u00e1nica, incrementa la adsorci\u00f3n de los plaguicidas estudiados, lo cual reduce intensamente su movilidad y por lo tanto, su capacidad de lixiviaci\u00f3n. De acuerdo con ello, podemos afirmar que la adici\u00f3n de residuos org\u00e1nicos al suelo origina un efecto beneficioso al reducir el riesgo de contaminaci\u00f3n de aguas subterr\u00e1neas. por otra parte, los experimentos fotocatal\u00edticos realizados confirman que la adici\u00f3n de semiconductores (tio2 y zno) en combinaci\u00f3n con un aceptor de electrones (na2s2o8) aumenta en gran manera la velocidad de degradaci\u00f3n de los plaguicidas estudiados en comparaci\u00f3n con los ensayos fotol\u00edticos, observando un aumento de la mineralizaci\u00f3n, aunque no completo, debido a la formaci\u00f3n de intermedios de reacci\u00f3n, algunos de los cuales han sido identificados. En cuanto a la eficacia de los catalizadores empleados, zno presenta mayor efectividad que tio2. En las condiciones experimentales empleadas, los tiempos medios calculados para el sistema zno\/na2s2o8 oscilaron entre 3 y 7 minutos. en conclusi\u00f3n, podemos afirmar que el empleo de materiales semiconductores como tio2 y zno en t\u00e1ndem con na2s2o8 y una fuente de energ\u00eda renovable como es la luz solar se presenta como una tecnolog\u00eda efectiva, r\u00e1pida y econ\u00f3mica para la remediaci\u00f3n de aguas superficiales y\/o subterr\u00e1neas contaminadas con plaguicidas, sobre todo, en determinadas zonas mediterr\u00e1neas como el sureste espa\u00f1ol, el cual recibe m\u00e1s de 3.000 horas de sol al a\u00f1o. palabras clave: agua, degradaci\u00f3n, lixiviaci\u00f3n, plaguicidas, suelo, sustancias prioritarias y preferentes, fotocat\u00e1lisis solar. reclamation of water polluted by pesticides (priorority and preferential substances) with high potential leaching through solar heterogeneous photocatalysis jos\u00e9 \u00e1ngel escudero garc\u00eda department of agricultural chemistry, geology and pedology. University of murcia. Spain. ph. D. Dissertation to obtain the doctor in chemistry.  abstract leaching, the movement of water and dissolved chemicals through the soil, of pesticides into the groundwater from agricultural practices is receiving increasing attention in european countries because a high percentage of the drinking water is extracted from groundwater. For this reason, the eu has established the individual (0.1 \u00c2\u00b5g l?1) and total (0.5 \u00c2\u00b5g l?1) concentrations of pesticides in drinking water to safeguard consumers from harmful effects (directive 2006\/118\/ec). under certain conditions, some pesticides may leach to the groundwater after normal field applications. In this process, multiple factors such as the physicochemical properties of the agrochemicals used, soil hydrological processes and management, as well as soil properties (texture, clay content, organic matter and permeability), play a decisive role. However, among soil properties, the organic carbon (oc) content is the single factor that has maximum influence on pesticide adsorption and mobility in soil. Soils of low oc content have a low capacity for retarding pesticide mobility, since the soil organic matter (om), especially humic substances, is the primary adsorbent for pesticides. At present, the addition of organic amendment (oa) to soils is being studied to understand any effect it may be on pesticide sorption and movement through the soil profile in order to minimize the risk of water pollution associated with rapid run-off and leaching. However, pesticide behavior in amended soils has been reported to have different responses and a variety of influences has been recognized. The main benefit concerning the sorption of pesticides to om is that it generally restricts leaching. However, decreased leaching may not only be due to the presence of additional om in the amended soil, but also to structural changes in the porosity induced by the increased oc content. pesticides can enter in water bodies via diffuse or via point sources. Diffuse pesticide input paths into groundwater are leaching through the soil and unsaturated zone and infiltration through riverbanks and riverbeds. The contamination of water bodies with agricultural pesticides can pose a significant threat to aquatic ecosystems and drinking water resources. Concretely, europe confronts enormous groundwater pollution problems with agriculture being the biggest polluter. The majority of europeans (about 60-65 %) rely on groundwater for drinking water purposes, and its use is threatened by the leaching of pesticides and nitrates from agriculture. Therefore, effective, low-cost and robust methods to decontaminate waters polluted with pesticide residues are needed, as long as they do not further stress the environment or endanger human health. conventional biological treatments of water offer some advantages such as their low cost and easy operation although they are not very effective for pesticide removal due to their low biodegradability. Thus, numerous studies have demonstrated that pollutants can be removed from water by advanced oxidation processes (aops) such as o3\/uv, h2o2\/uv, h2o2\/o3\/uv, homogeneous photo-fenton, and\/or heterogeneous photocatalysis]. Aops have been broadly defined as near ambient temperature treatment processes based on highly reactive radicals, especially the hydroxyl radical (ooh), as the primary oxidant while the other radical and active oxygen species are superoxide radical anions (o2o?), Hydroperoxyl radicals (ho2o), triplet oxygen (3o2), and organic peroxyl radicals (rooo). Clearly, the ooh radical (e0= 2.8 v) is among the strongest oxidizing species used in water and wastewater treatment and offers the potential to greatly accelerate the rates of pollutant oxidation. Among aops, heterogeneous photocatalysis is a process of great potential for pesticide residues abatement in water. Heterogeneous photocatalysis is a technique of environ-mental interest for the treatment of polluted water combining the low cost, the mild conditions and the possibility of using sunlight as the source of irradiation. the heterogeneous solar photocatalytic detoxification process consists of making use of the near-ultraviolet and visible bands of the solar spectrum to photo-excite a semiconductor (sc) material in contact with water and in the presence of oxygen with the purpose of generating radicals, mainly ?Oh which is a powerful non-specific oxidant (e0 = 2.8 v). Photons whose energy is equal to or greater than the band-gap energy (eg) of the semiconductor eg (hv ? Eg), can be absorbed exciting the valence band electrons. As consequence, a positive photohole (h+) in the valence band and a photoelectron (e-) in the conduction band are formed (hv + sc ? E- + h+). The e-\/h+ pairs generated serve as the oxidizing and reducing agents. Simultaneously, a spontaneous adsorption occurs and according to the redox potential of each adsorbate, an e- transfer proceeds towards acceptor molecules (a(ads) + e- ? A-(ads)), whereas a positive h+ is transferred to a donor molecule (d(ads) + h+ ? D+(ads)). in this view, the aim of this research was to assess the photoactivity of tio2 and zno on the degradation of different pesticides, included as priority hazardous pollutants by the eu, under sunlight irradiation at pilot plant scale. For this purpose, we have previously studied their leaching potential through the soil and the role of the most important operating parameters (proportion of crystalline phases, catalyst loading, effect of the addition of an electron acceptor, ph, light intensity, initial concentration of pollutants, and interfering substances) on the photooxidation of the studied pesticides. results show that addition of exogenous organic matter -composted sheep manure (csm), spent coffee grounds (scg), composted pine bark (cpb) and coir (cr)- to a typical mediterranean soil (hipercalcic calcisol) with low content of organic matter increased the sorption of the studied pesticides. Downward movement of all pesticides was strongly reduced in amended soils most likely because the enhanced sorption preventing pesticide leaching. Accordingly to the obtained results, addition of organic wastes could be beneficial in reducing the risk of groundwater pollution associated with the presence of the studied pesticides in the soil. on the other hand, photocatalytic experiments showed that the addition of semiconductors (zno and tio2) in tandem with an electron acceptor (na2s2o8) strongly enhances the degradation rate of the pesticides compared with the results obtained in the photolytic tests. This is accompanied by increased but incomplete mineralization, thus implying the formation of stable reaction intermediates; several of these were successfully identified and quantified. The efficiency of the catalysts in the photooxidation of the pesticides was in the order: zno &gt; tio2. In our conditions, the half-lives ranged from 3 to 7 min in the zno\/na2s2o8 system.  in summary, the use of semiconductor materials such as zno or tio2, in combination with na2s2o8 and a renewable source of energy like sunlight, offers an effective, rapid and economical technology for surface and groundwater remediation, mainly in some mediterranean areas like se of spain receiving more than 3000 h of sunlight per year. keywords: degradation, soil, leaching, drinking water, pesticides, priority and preferential substances, solar photocatalysis.<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Regeneraci\u00f3n de aguas contaminadas por plaguicidas (sustancias prioritarias y preferentes), con elevado potencial de lixiviaci\u00f3n, mediante fotocat\u00e1lisis solar heterog\u00e9nea.<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Regeneraci\u00f3n de aguas contaminadas por plaguicidas (sustancias prioritarias y preferentes), con elevado potencial de lixiviaci\u00f3n, mediante fotocat\u00e1lisis solar heterog\u00e9nea. <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Jos\u00e9 Angel Escudero Garcia <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Murcia<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 16\/07\/2015<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Simon Navarro Garcia<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: mercedes Llorens pascual de riquelme <\/li>\n<li>Jos\u00e9 Luis Moreno ortego (vocal)<\/li>\n<li>  (vocal)<\/li>\n<li>  (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Jos\u00e9 Angel Escudero Garcia Resumen la lixiviaci\u00f3n (movimiento del agua y los compuestos disueltos a trav\u00e9s del [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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