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Schlief, Jeanette. "The fate of leaf litter in extremely acidic mining waters." Berlin dissertation.de, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2828582&prov=M&dok_var=1&dok_ext=htm.
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Alhousari, Fadi. "Fate and behaviour of acidic rice herbicides in lagoon waters of camargue." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10022/document.
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Le delta du Rhône est une vaste plaine alluviale recouverte d’étangs et de lagunes, parsemée de cultures diverses, principalement du riz (21’100 ha en 2009, Centre Français du Riz, 2010). Des herbicides répandus en avril (pré levée, prétilachlor) et en juin (poste levée, bentazone ; MCPA et dichlorprop) sont utilisés dans la riziculture pour lutter contre les mauvaises herbes. L’étang de Vaccarès, qui est classé «réserve de biosphère» par l’UNESCO pour sa grande richesse biologique reçoit des pesticides directement issus des rizières par les canaux de drainage. D’un point de vue scientifique, peu d’études sont consacrées au devenir des pesticides dans les eaux estuariennes. En outre, la plupart de ces études ont été focalisées sur la photochimie bien que la biodégradation soit impliqué dans l’atténuation des pesticides. Alors le but de ce travail de thèse est de comprendre le devenir des herbicides de riziculture en évaluant le rôle de la photochimie direct et indirect et de la biodégradation. Nous avons développé donc un modèle capable de décrire la transformation de molécules organique par la voie photochimique dans les eaux estuariennes. Enfin nous avons déterminé les processus principaux impliqués dans l'atténuation rapide des herbicides de riziculture en CamargueThe Ile de Camargue basin is the central part of the Rhône Delta in the south of France included between the two branches of the river. The higher parts of this area are agricultural lands, mainly rice fields, whereas the lower parts are lagoons and natural wetlands of international importance for biodiversity preservation.Bentazone, dichlorprop, and MCPA are post-emerging herbicides applied in rice fields from mid April to mid June. Rice fields grown under flooded conditions represent an environment where these conditions increase the potential for pesticides to transport in runoff from rice fields to non- target surface waters.To predict their fate in the surface waters of the Camargue and to asses their risk, it is necessary to understand their chemical reaction under environmental conditions.Reactive photoinduced species (RPS, hydroxyl radical HO., singlet oxygen 1O2 and dissolved organic matter triplet state) in estuarine waters (Vaccarès lagoon) were characterized experimentally to estimate the role of photochemistry in rice paddy. We then developed a kinetic model describing the solar photo-transformation of xenobiotic organic compounds induced by the three different photooxidants RPS. Sunlight photodegradation of bentazone, dichlorprop (DCPP), MCPA and alachlor (used as a surrogate for the similar Pretilachlor, pre-emergence herbicide) and microbial transformation were conducted experimentally to estimate near-surface half-lives in surface water. Parallel to the experimental study, an assessment of the elimination rates of those herbicides by sorption and sedimentation, and volatilization were obtained by the model MASAS (Modelling of Anthropogenic Substances in Aquatic Systems).The half-lives of the herbicides obtained experimentally were then compared with those obtained from field data. This allowed to assessing the main processes involved in the attenuation of herbicide concentrations
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Di, Capua Francesco. "Sulfur-based denitrification of organic-deficient, acidic, low temperature and nickel contaminated waters in fluidized-bed reactors." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1106.
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La dénitrification autotrophe à l’aide de composés réduit de soufre est une approche intéressante pour le traitement biologique des contaminations azotées et des effluents pauvre en matière organique. La dénitrification autotrophe utilise des composés inorganiques comme sources d'énergie et de carbone. L'absence de matière organique élimine le besoin de post-traitements pour éliminer l'excès de carbone organique et limite la formation sous-produits d’oxydation dans le cadre de la production d’eau potable. Les eaux usées provenant des industries métallurgiques et minières ont généralement un faible pH, des températures basses et des concentrations élevées en métaux lourds. L'élimination biologique de l'azote est un défi parce que les bactéries dénitrifiantes prospèrent habituellement à pH neutre et à températures ambiantes (20-30 °C).Le but de cette thèse était de développer un procédé robuste de dénitrification à base de soufre dans des bioréacteurs à pH acide, températures psychrophiles (< 20 °C) et concentrations élevées en nickel. Le procédé a été optimisé au préalable avec des essais biologiques étudiant l'influence de la source de soufre (S2O32-, S0 biogénique et le synthétisé chimiquement), de la taille des particules de S0 (poudre et lentilles), de la culture dénitrifiante (cultures pures et mixtes de Thiobacillus) et de la température (6-30 °C) sur la cinétique de la dénitrification. L'utilisation de S2O32- et d’une culture pure de T. denitrificans ont permis d’atteindre des rendements de dénitrification les plus élevés. Le soufre élémentaire biogénique a été testé pour la première fois comme donneur d'électrons pour la dénitrification, montrant des taux de dénitrification 1.7 fois plus élevés que ceux obtenue avec de la poudre de S0 synthétisé chimiquement. Les taux de la dénitrification avec le S2O32- augmentent exponentiellement avec la température et les calculs avec l'équation d'Arrhenius donnent une énergie d'activation apparente Ea de 76.6 kJ/mol.Deux réacteurs à lit fluidisé (FBR) ont été utilisés pour étudier la dénitrification avec S2O32- à différents pH (5.25-7.00) et températures décroissantes (3-20 °C). Des rendements de dénitrification > 99% ont été observés pour eaux usés présentant des pH compris entre 5.75 et 5.30. L'addition d'une unité de carbonatation fournissant au biofilm du CO2 comme source de carbone supplémentaire, permettant une dénitrification complète à un pH de 4.75. Dans le même FBR, des taux de charge d'azote élevés (jusqu'à 3,3 kg N-NO3-/m3 d) avec le thiosulfate ont été maintenu à des températures aussi basses que 3 °C. L'impact de deux composés du Nickel (NiEDTA2- et NiCl2) sur la dénitrification à base de soufre a été étudiée dans deux FBR en parallèle à 20 (± 2) °C et des concentrations de nickel variant dans la gamme de 5-200 mg Ni/L. Dans des bioessais discontinues, 25-100 mg Ni/L de NiCl2 ont inhibée l'élimination de NO3- de 7-16%, alors qu'aucune inhibition n'a été observée avec NiEDTA2-. L'EDTA non complexée a inhibée la dénitrification à des concentrations supérieures à 100 mg/L. Les deux composés de Ni ont montré aucun effet négatif sur la dénitrification en FBR aux concentrations testées. Le bilan massique du nickel, la caractérisation de la phase solide et la modélisation thermodynamique ont révélé que des précipités de nickel ont été principalement éliminés avec l'effluent. Les phosphates, sulfures et oxydes de nickel ont été déterminés comme les principaux précipités de nickel et étaient principalement amorphe.Les FBRs se sont révélés être bioprocédés robustes pour l'élimination de l'azote à pH acide, pour des températures psychrophiles et des concentrations élevées de nickel. Les résultats de cette étude sont d'un grand intérêt pour le traitement des eaux souterraines et minières contaminés par les nitrates dans les régions froides du monde et également pour les eaux usées industrielles acides et chargées en métaux lourdsAutotrophic denitrification driven by reduced sulfur compounds is a promising and cost-effective biological nitrogen removal process, recommended for the treatment of organic-deficient waters, e.g. groundwater and several industrial wastewaters. Autotrophic denitrifiers utilize inorganic compounds as sources of energy and carbon. The lack of organics eliminates the need of post-treatments to remove excess organic carbon and limits the formation of harmful organic byproducts (e.g. trihalomethanes, THM), resulting in a clean and safe treatment also for drinking water. Wastewaters from mining and metal-finishing industry commonly feature low pH and temperatures as well as high heavy metal concentrations. Nitrogen removal from these waters is a technical challenge, since denitrifying bacteria usually thrives at circumneutral pH and ambient temperatures (20-30°C).The aim of this study was to develop a robust and efficient sulfur-based denitrification bioreactor process able to tolerate acidic pH, psychrophilic temperatures (< 20°C) and high nickel concentrations. The process was preliminary optimized in batch bioassays investigating the influence of sulfur source, i.e. thiosulfate (S2O32-) and biogenic and chemically synthesized elemental sulfur (S0), S0 particle size (powder and lentils), denitrifying culture (pure and mixed cultures of Thiobacillus) and temperature (6-30°C) on denitrification kinetics. The use of S2O32- and a pure culture of Thiobacillus denitrificans resulted in the highest denitrification rates. Biogenic S0 was tested for the first time as electron donor for autotrophic denitrification, showing 1.7-fold faster NO3- removal than that achieved with chemically synthesized S0 powder. The rates of thiosulfate-driven denitrification exponentially increased with temperature, being modeled according to the Arrhenius equation with an apparent activation energy Ea of 76.6 kJ/mol and a temperature coefficient Q10 of 3.0.Fluidized-bed reactors (FBRs) were used to investigate continuous thiosulfate-driven denitrification under decreasing feed pH (5.25-7.00) and temperatures (3-20°C). Denitrification efficiencies > 99% were observed at feed and effluent pH as low as 5.75 and 5.30, respectively. At lower feed pH values, the denitrification activity rapidly decreased due to an inorganic carbon deficiency. The addition of a carbonation unit providing CO2 as supplemental carbon source to the FBR biofilm allowed complete denitrification even at a pH of 4.75. In the same FBR, high-rate (up to 3.3 kg N-NO3-/m3 d) thiosulfate-driven denitrification was maintained at temperatures as low as 3°C. The impact of two Ni compounds, i.e. NiEDTA2- and NiCl2, on sulfur-based denitrification was investigated in a parallel FBR at 20 (±2)°C and feed Ni concentrations in the range of 5-200 mg Ni/L. Preliminary batch bioassays were carried out to assess Ni and free EDTA toxicity on sulfur-based denitrification. In batch bioassays, 25-100 mg Ni/L of NiCl2 inhibited NO3- removal by 7-16%, whereas no inhibition was observed with NiEDTA2-. Free EDTA inhibited sulfur-based denitrification at concentrations exceeding 100 mg/L. Both Ni compounds showed no detrimental effects on sulfur-based denitrification in FBR at the tested concentrations. Nickel mass balance, solid-phase characterization and thermodynamic modeling revealed that nickel precipitates were mostly washed out with the effluent, due to the slow Ni precipitation kinetics and high upflow velocities in the FBR. Nickel phosphate, sulfide and oxide were indicated as the main nickel precipitates and were mostly amorphous.FBRs were shown to be powerful and robust biofilm systems for nitrogen removal under acidic pH, psychrophilic temperatures and high nickel concentrations. The results of this study are of great interest for the treatment of NO3- contaminated ground and mining waters in cold regions (e.g. Canadian and Scandinavian regions) as well as acidic and heavy-metal-laden wastewaters
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Musibono, Diudonné-Athanase Eyul'anki-Ekwalang'Ayor. "Toxicological studies of the combined effects of aluminium, copper and manganese on a freshwater amphipod in acidic waters." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/19382.
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This thesis describes the combined toxicity in aqueous solutions of three common metals (Al, Cu and Mn) on the endemic freshwater amphipod Paramelita nigroculos (Barnard) from the south-western Cape region of South Africa. The aims of the work were three-fold: to examine the toxic effects of combinations of the three metals; to investigate such effects on an indigenous aquatic organism; and, to investigate eh adequacy of the South African "Guidelines for aquatic ecosystems", which are derived from the data based on the effects of individual elements.
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Warby, Richard Ashley Frank. "The chemical response of surface waters and organic soils across the northeastern United States, following reduced inputs of acidic deposition 1984-2001 /." Related electronic resource:, 2007. http://proquest.umi.com/pqdweb?did=1342747271&sid=1&Fmt=2&clientId=3739&RQT=309&VName=PQD.
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Luís, Ana Teresa Lopes Ferreira. "Integration of geochemical and biological modifications in mining areas: waters, sediments and diatoms." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12332.
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Doutoramento em GeociênciasThe development of mining activities over thousands of years in the region of Aljustrel is nowadays visible as a vast area of ore tailings, slag and host rocks of sulphides mineralization. The generation of acidic waters by the alteration of pyritic minerals - Acid Mine Drainage (AMD) - causes a significant impact on the river system both in the south of the village (Rib ª. Água Forte) and in the north of it (Rib ª. Água Azeda and Barranco do Farrobo), which is reflected in extremely low pH values (< 3) and high concentrations of As, Cd, Cu, Fe, Mn, Pb, Zn and sulphates. This study aimed to assess the environmental impacts extent, integrating geochemical (surface waters and stream sediments) and biological (diatoms) parameters. Three groups of sites were defined, based on sediments and water analysis, which integration with diatom data showed the same association of groups: Group 1- impacted, with acidic pH (1.9-5.1), high metal contents (0.4-1975 mg L-1) and Fe-Mg-sulphate waters, being metals more bioavailable in waters in cationic form (Me2+); mineralogically the sediments were characterized by phyllosilicates and sulphates/oxy-hydroxysulphate phases, easily solubilized, retaining a high amount of metals when precipitated; dominant taxon was Pinnularia aljustrelica (a new species); Group 2- slightly impacted, weak acid to neutral pH (5.0-6.8), metal contents not so high (0.2-25 mg L-1) and Fe-Mg-sulphate to Mg-chloride waters; dominant taxa were Brachysira neglectissima and Achnanthidium minutissimum; Group 3- unimpacted, alkaline pH (7.0-8.4), low metal contents (0-7 mg L-1) with Mg-chloride waters. In this group, metals were associated to the primary phases (e.g. sulphides), not so easily available; the existence of high chloride contents explained the presence of typical taxa of brackish/marine (e.g. Entomoneis paludosa) waters. Taxonomical aspects of the diatoms were studied (discovery of a new species: Pinnularia aljustrelica Luis, Almeida et Ector sp. nov.), as well as morphometric (size decrease of diatoms valves, as well as the appearance of deformed valves of Eunotia exigua in Group 1 and A. minutissimum in Group 2) and physiological (effective to assess the effects of metals/acidity in the photosynthetic efficiency through PAM Fluorometry) aspects. A study was carried out in an artificial river system (microcosm) that aimed to mimic Aljustrel’s extreme conditions in controlled laboratory conditions. The chronic effects of Fe, SO42- and acidity in field biofilms, inoculated in the artificial rivers, were evaluated as well as their contribution to the communities’ tolerance to metal toxicity, through acute tests with two metals (Cu and Zn). In general, the effects caused by low pH values and high concentrations of Fe and SO42- were reflected at the community level by the decrease in diversity, the predominance of acidophilic species, the decrease in photosynthetic efficiency and the increase of enzymatic (e.g. catalase, superoxide dismutase) and non-enzymatic activities (e.g. total glutathione and total phytochelatins). However, it was possible to verify that acidity performed a protective effect in the communities, upon Cu and Zn addition. A comparative study between Aljustrel mining area and New Brunswick mining area was carried out, both with similar mining and geological conditions, reflected in similar diatom communities in both mines, but in very different geographic and climatic areas.
O desenvolvimento de actividades mineiras ao longo de milhares de anos na região de Aljustrel, reflecte-se actualmente em vastas áreas ocupadas por escombreiras com minério, escórias e rochas encaixantes das mineralizações de sulfuretos. A geração de águas ácidas por oxidação dos sulfuretos - Drenagem Ácida de Mina (DAM) - provoca um impacte significativo na rede hidrográfica, quer na zona sul da vila de Aljustrel (Ribª. de Água Forte) quer na região norte da mesma (Ribª. da Água Azeda e Barranco do Farrobo), que se traduz em valores extremamente baixos de pH (<3) e elevadas concentrações de As, Cd, Cu, Fe, Mn, Pb, Zn e SO4. Este estudo teve como objectivo avaliar a extensão destes impactos ambientais, integrando parâmetros geoquímicos (águas superficiais e sedimentos de corrente) e biológicos (diatomáceas). Três grupos de locais foram definidos com base na análise dos sedimentos de corrente e águas superficiais, cuja integração com as diatomáceas mostrou a mesma associação de grupos: Grupo 1- impactados, com pH ácido (1.9-5.1), conteúdo em metais alto (0.4-1975 mg L-1) e águas sulfatadas ferromagnesianas, estando os metais mais biodisponíveis nas águas sob a forma catiónica (Me2+); mineralogicamente os sedimentos caracterizaram-se por existência de fases filossilicatadas e sulfatadas/óxi-hidroxisulfatadas facilmente solubilizáveis que retêm grande quantidade de metais aquando da sua precipitação; o taxon dominante foi Pinnularia aljustrelica (espécie nova); Grupo 2- ligeiramente impactados, pH ácido fraco a neutro (5.0-6.8), conteúdo em metais pouco elevado (0.2-25 mg L-1) e com águas do tipo sulfatadas ferromagnesianas a cloretadas magnesianas; os taxa dominantes foram Brachysira neglectissima e Achnanthidium minutissimum); Grupo 3- não impactados, pH alcalino (7.0-8.4), conteúdo em metais baixo (0-7 mg L-1), águas essencialmente cloretadas magnesianas. Neste grupo, os metais estavam associados às fases primárias (por exemplo, sulfuretos), não se encontrando por isso tão disponíveis; verificam-se altos conteúdos em cloro o que justifica a presença de taxa típicos de águas salobras/marinhas (por exemplo, Entomoneis paludosa). As amostras de diatomáceas foram estudadas do ponto de vista taxonómico (descoberta de uma nova espécie: Pinnularia aljustrelica Luís, Almeida et Ector sp. nov.), morfométrico (diminuição do tamanho das valvas de diatomáceas, assim como o aparecimento de formas deformadas de Eunotia exigua no Grupo 1 e A. minutissimum no Grupo 2), fisiológico (uso da Fluorometria de Pulso Modulado foi eficaz na avaliação dos efeitos dos metais/acidez na eficiência fotossintética). Foi efectuado um estudo em sistema de rios artificiais (microcosmos) que teve como objectivo simular as condições extremas existentes em Aljustrel em condições controladas de laboratório. Avaliaram-se os efeitos crónicos do Fe, SO42- e acidez nas comunidades inoculados nos rios artificiais e a sua contribuição para a tolerência dessas comunidades à toxicidade a dois metais (Cu e Zn) através de testes agudos. De um modo geral, os efeitos provocados pelos valores baixos de pH e pelos elevados teores em Fe e SO42- reflectiram-se a nível das comunidades de diatomáceas, na diminuição da diversidade, no predomínio de espécies acidofílicas, na diminuição da eficiência fotossintética e no aumento das actividades enzimáticas e não enzimáticas. Contudo, aquando da adição do Cu e do Zn, a acidez teve um efeito protector nas comunidades. Foi também efectuado um estudo comparativo entre a zona mineira de Aljustrel e a zona mineira de New Brunswick (Canadá) que apresentavam condições geológicas e de mineração semelhantes, refletindo-se em comunidades de diatomáceas análogas, mas com uma localização geográfica e climática muito distinta.
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Brooks, Jenkins Gareth. "Amelioration of acidity in fresh waters : individual to ecosystem level responses." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8981.
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The extensive acidification of fresh waters across Europe and North America during the 20th century led to extensive and widespread loss of species, which fundamentally changed the structure of resident communities. While attempts to limit or halt acidifying emissions have been successful in reversing the chemical consequences of acidification, any corresponding biological recovery has been patchy at best. The main aim of this thesis was to investigate potential ecological constraints on this biological recovery, ranging from interactions between individuals to ecosystem-level processes, using a model stream system that has been extensively studied for over 40 years. I used a combination of long-term survey data and experiments, both in the field and the laboratory, to provide evidence that the lag in recovery of acidified aquatic communities is due to intrinsic resistance to re-colonisation by acid-sensitive species, as a result of both direct and indirect interactions between predators and prey. However, there is also evidence of recovery at an ecosystem level, with rates of microbial decomposition increasing – a key link in the transfer of energy to higher trophic levels, which could be facilitating population increases in large-bodied predators. These findings increase our understanding of the drivers which govern the structure and function of ecological networks in response to an important climatic stressor. This is especially relevant given the rapid industrialisation of countries such as India and China, which could well soon experience anthropogenic acidification on a significant scale.
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Owe, Lars-Erik. "Characterisation of Iridium Oxides for Acidic Water Electrolysis." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14450.
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Curren, Meredith S. "Partitioning of acidic solutes between water and supercritical carbon dioxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0021/NQ48326.pdf.
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Curren, Meredith S. (Meredith Susan) Carleton University Dissertation Chemistry. "Partitioning of acidic solutes between water and supercritical carbon dioxide." Ottawa, 1999.
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Tereshchenko, I. M. "The effects of acidification on fresh water life." Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/34942.
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Signs that a water body is becoming acidified are clearer water and declining fish populations. The clearness is primarily due to that the humic substances that normally colour the water, precipitate and settle on the lake floor. The main reason for fish stocks declining, both overall and in number of species, is failure to reproduce in acidic water. Many other biological changes occur, too, when the water becomes acidified.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34942
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Nowicki, Thomas Edward. "The impact of plantations of Pinus spp. on the chemical properties of soils and stream waters in South African upland catchments." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/17332.
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Bibliography: pages 171-181.Studies of forest ecosystems have indicated that internal sources constitute a significant component of the acid load to forest soils and can result in significant decreases in soil pH, acid neutralising capacity and base status. Despite this, the possibility that these processes can result in a significant transfer of acidity to drainage solutions and consequently to associated surface waters has, to a large extent, been discounted due to the self-limiting nature of " natural" acidification processes which purportedly do not involve significant concentrations of the strong acid anions NO₃⁻, SO₄²⁻ and Cl⁻. In South Africa, extensive plantations of Pinus spp. (pine) are developed in mountainous regions that were previously covered by grassland or fynbos (macchia) vegetation and are mostly not believed to be influenced by significant atmospheric pollution. Thus, a good opportunity exists to study the effects of afforestation without the superimposed influence of acid deposition. This thesis documents the results of a regional investigation of the geochemical impact of pine afforestation in South Africa. The study focuses specifically on factors relating to the transfer of soil acidity to drainage waters. The key questions that are addressed are : 1) to what extent is soil acidification, as previously documented for plantations in the eastern seaboard region of southern Africa, prevalent in other forestry areas within South Africa?; 2) in the absence of acid deposition, can afforestation cause enhanced concentrations of strong acid anions in soil solutions and drainage waters, and can this lead to the transfer of large quantities of acidity from forest soils to surface waters ?; 3) does afforestation-induced acidification lead to increased concentrations of environmentally important metals such as Al and Mn in soil solutions and surface waters ?; and 4) how does afforestation affect the quantity of dissolved organic matter in soils and streams?
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GALDINO, ANA CAROLINA PATTACINI. "REMOVAL OF HUMIC ACIDS FROM WATERS WITH PURPOSE POTABILITY USING FENTON REAGENT AS PRÉ-OXIDANT IN WATER TREATMENT PROCESSES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29711@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
A água potável é essencial para uma boa qualidade de vida e saúde da população. Nos mananciais, a água naturalmente encontrada possui matéria orgânica e microorganismos, alguns até mesmo patogênicos, sendo necessário o seu tratamento em estações de tratamento de água (ETAs). O cloro é o principal reagente atualmente utilizado como pré-oxidante da matéria orgânica em ETAs, gerando compostos organo-halogenados de características cancerígenas. Neste trabalho foi realizado um estudo do reagente de Fenton como pré-oxidante com o fim de degradar os ácidos húmicos (AH), que são os principais constituintes da matéria orgânica naturalmente encontrada em águas de mananciais, sem a geração dos compostos organo-halogenados. Para isto, foram realizados experimentos de acordo com um planejamento fatorial 23 que investigou a influência de três variáveis na degradação de AH: pH, dosagem de peróxido de hidrogênio e razão molar [H2O2]:[Fe elevado a 2 positivo]. Os resultados obtidos a partir destes experimentos mostraram que todas as variáveis influenciaram na degradação do AH, de forma que o aumento tanto da dosagem de peróxido de hidrogênio quanto da razão molar [H2O2]:[Fe elevado a 2 positivo] gera o aumento na degradação de AH. Com relação ao pH, o aumento desta variável gerou uma ligeira queda na degradação de AH. Assim, a partir de todos os experimentos verificou-se que aquele de melhor resultado apresenta as seguintes condições operacionais: dosagem de peróxido de hidrogênio igual a 42,98 mg/L, [H2O2]:[Fe elevado a 2 positivo] igual 3:1, pH igual a 7. Nestas condições operacionais, após 5 minutos de reação, a redução de AH foi de 95,66 por cento, a redução de COT de 24,94 por cento e a velocidade inicial de degradação de AH de 9,38 mg/L.min.
Drinking water is essential to a good quality of life and health of the populations. In the surface, the water found naturally contains organic matter and microorganisms, some even pathogenic, requiring their removal in water treatment plants (WTPs). Chlorine is the main reagent currently used as pre-oxidant of the organic matter in WTPs, generating chlorinated organic compounds of carcinogenic characteristics. In this project a study of the Fenton reagent as pre-oxidant has been conducted in order to degrade the humic acids (HA), which are the main constituents of the organic matter naturally found in water sources without generating the chlorinated organics. For this, experiments have been conducted according to a factorial design 23 which investigated the influence of three variables in the HA degradation: pH; hydrogen peroxide dosage; and molar ratio [H2O2]:[Fe to the power of 2 positive]. The results obtained from these experiments showed that all variables influence the degradation of HA, so that the increase of the hydrogen peroxide dosage as well as the molar ratio [H2O2]:[Fe to the power of 2 positive] increase HA degradation. With regard to the pH, the increase of this variable generates a slight drop in AH degradation. Thus, from all experiments it has been verified that that the best result were obtained in the following operating conditions: hydrogen peroxide dosage equal 42,98 mg/L, [H2O2]:[Fe to the power of 2 positive] equal 3:1, pH equal 7. Under these operating conditions, after 5 minutes of batch reaction, the reduction of HA was 95,66 percent, the TOC reduction of 24,94 percent and the initial rate of HA degradation of 9,38 mg/L.min.
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Kumai, Yusuke. "Mechanisms of Na+ Homeostasis by Zebrafish (Danio Rerio) in Acidic Water." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26205.
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Zebrafish, Danio rerio, are able to survive exposure to extreme acidity (pH 4). Because previous studies demonstrated that disruption of ionic balance during exposure to acidic water is the major cause of mortality in acid-sensitive freshwater species, the focus of this thesis was to characterize the molecular mechanisms enabling zebrafish to maintain their Na+ homeostasis following exposure to acidic water. Initial findings (Chapter 2) demonstrated that branchial mRNA expression of selected isoforms of claudins, major components of tight junctions, are altered in an isoform-dependent manner, suggesting the potential regulation of epithelial permeability to minimize ion loss. Concurrently, a marked stimulation of Na+ uptake was observed in adults and larvae following acid-exposure. Because of the uniqueness of this response (increasing Na+ uptake in acidic water) among freshwater teleosts, the mechanisms related to Na+ uptake and its stimulation were investigated further (Chapters 3 - 7). Pharmacological treatments and gene knockdown approaches revealed that a functional metabolon consisting of an apically expressed Na+-H+-exchanger (NHE3b) in association with an apically expressed ammonia-conducting channel (Rhcg1), enables Na+ uptake in acidic water.
During chronic (>1 day) exposure to acidic water, cortisol (via glucocorticoid receptors) and catecholamines (via β-adrenergic receptors) are involved in stimulating Na+ uptake. Although catecholamines may act on both NHE3b and Na+-Cl- co-transporter (NCC), the effects of cortisol on Na+ uptake are mediated primarily by activation of NHE3b. On the other hand, during acute (<3 h) exposure to acidic water, cortisol does not appear to affect Na+ uptake; rather, the stimulation of Na+ uptake appears to be mediated by angiotensin II and catecholamines. Cyclic AMP (cAMP), a signalling molecule synthesized following the activation of β-adrenergic receptors, is critically involved in stimulating Na+ uptake, likely via activation of NHE3b and NCC. In agreement with this idea, ionocytes that express NHE3b also express high levels of β-adrenergic receptor (propranolol binding sites) as well as trans-membrane adenylyl cyclase (forskolin binding sites).
Taken together, the results of this thesis provide fresh insight into the mechanisms of osmoregulation in freshwater (FW) fish. In particular, the data reveal the presence of complex pathways regulating Na+ uptake in zebrafish exposed to acidic water. The relative importance of the various pathways depends in part on the duration of exposure; acute versus chronic.
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Sanger, Luke. "Acidic deposition effects on upland organic soils and their drainage water." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU058910.
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The work presented in this thesis investigates the effects of precipitation chemistry on the chemical characteristics of upland organic soils in the UK and their associated drainage waters. It also describes effects on a number of microbially-mediated processes and concludes with a study on methods for the amelioration of peat acidification. Data presented in chapters 3, 5 and 6 have recently been published or accepted for publication (Sanger et al. 1993 a. 1993 b and 1993 c). The first chapter describes the nature of soil acidity and reviews the relevant literature on the effects of acidic deposition, with particular emphasis on upland organic soils and their drainage waters. Chapter 2 describes a field survey carried out in the UK which investigates relationships between the exchangeable and total element chemistry of peat and precipitation chemistry. The results showed that peat collected from areas receiving high concentrations of H+, NH4+, SO42- andNO3- in precipitation were characterised by high extractable NH4+ and total P. and low extractable NO3-, base saturation and exchangeable Ca2+ and Mg2+. TheNH4+ concentration in precipitation was strongly related to a number of soil chemical parameters and the results suggest that future changesin NH4+ inputsto peatscould significantlyeffect soil and drainage water chemistry. The results also show that (1) processes involved in the cycling of N and P may have been altered by precipitation chemistry (2) exchangeable Ca2+ and Mg2+ have been displaced by NH4+ and H+ in areas with high acidic deposition. Peat from areas with a high marine input in precipitation contained high concentrations of exchangeable N+ and K+. Laboratory simulation studies (chapter 3 and 4) using intact peat monoliths were carried out to complement the regional survey described in chapter 2. They were set up to examine element fluxes from peats in relation to precipitation chemistry.
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Ashford, Emma J. "Synthesis of water-soluble polymers via atom transfer radical polymerisation." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341539.
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A study of the atom transfer radical polymerisation (ATRP) of water-soluble, acidic, monomers was carried out in aqueous media. The ATRP of sodium methacrylate (MAANa) produced polymers with controlled molecular weights and narrow polydispersities (Me/M, - 1.3) at 90°C. This is the first reported example of direct polymerisation of an acidic monomer via ATRP. Previously, such acidic polymers were produced by polymerisation of protected monomers. In this thesis, copper(l) bromide and iron(II) bromide were investigated as ATRP catalysts. Both were found to be effective when solubilised by 2,2'-bipyridine (bipy). Monomer conversions between 75 and 85 % were obtained in the presence of Cu(l)Brlbipy, and conversions as high as 94 % were obtained in the presence of Fe(II)Br2Ibipy. Kinetic studies carried out on the ATRP of MAANa using the CuBrlbipy catalyst and an oligo(ethylene glycol)-based initiator indicated that polymerisation proceeded via first order kinetics with respect to monomer consumption, and that molecular weight increased linearly with conversion. This is as expected for a living polymerisation. At approximately 75 - 85 % conversion, however, premature termination occurred. Both bromine microanalyses and 'n and 13CNMR studies indicated that the halide-capped polymer chain-ends undergo HBr elimination. Low molecular weight « 10,000 g mol") MAANa homopolymers and oligo(ethylene glycol)-sodium methacrylate block copolymers (PEG-b-PMAANa) were examined as possible macro initiators for the ATRP of sodium 4-styrenesulfonate (SSNa), potassium 3- sulfopropyl methacrylate (SPMAK) and sodium allyl sulfonate (SAS). PEG-b-PMAANa was found to initiate the ATRP of SSNa, yielding a polymer with controlled molecular weight and a polydispersity of 1.23. Initiation of the ATRP of SPMAK and SAS was less successful. This was likely due to the loss of functionality of the MAANa-based polymers. Block copolymers were obtained, however, by macroinitiating the aqueous ATRP of MAANa using a monomethoxy-capped oligo(ethylene glycol) methacrylate homopolymer. Successful ATRP of MAANa was also achievable at ambient temperatures in the presence of a co-solvent, 2-(dimethylamino)ethanol, DMAE. DMAE appears to dramatically increase the rate of polymerisation whilst still maintaining control when used in equimolar quantities (relative to the monomer). Polymers with predetermined molecular weights and narrow polydispersities were produced in good yield (up to 86 % conversion) within five minutes at 20°C. The ATRP of other hydrophilic monomers was also investigated, albeit in less detail. These monomers included sodium acrylate, mono-2-(methacryloyloxy)ethyl succinate, 2- hydroxyethyl acrylate, itaconic acid, and 2-acrylamido-2-methyl-propanesulfonic acid. Generally less control was achieved for such syntheses than for the ATRP of MAANa.
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D'sa, Jean V. "Rapid removal of toxicity of acid mine drainage contaminated sediments in a clean stream : relative contribution of acidity vs metals /." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1087840199.
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Check, Jason Kenneth. ""Characterization and removal of NOM from raw waters in coastal environments"." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-02162005-215318/unrestricted/check%5Fjason%5Fk%5F200505%5Fmast.pdf.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005.Michael Saunders, Committee Chair ; Paul Work, Committee Member ; Jaehong Kim, Committee Member. Includes bibliographical references.
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Buniazet, Zoé. "Vers une meilleure connaissance des propriétés acides des catalyseurs hétérogènes en présence d’eau : application à la déshydratation d’alcools biosourcés en oléfines." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1217.
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La valorisation de la biomasse en molécules plateformes, telles que les oléfines pour l'industrie des polymères, rend nécessaire l'adaptation des catalyseurs utilisés en pétrochimie à la transformation de composés fortement hydratés. Ces travaux de thèse ont permis de développer une méthode de caractérisation complète des catalyseurs acides en présence d'eau et en conditions réactionnelles. Cette méthode combine un examen des propriétés catalytiques en étudiant l'effet de l'eau sur des paramètres tels que le temps de contact, la température ou le vieillissement du catalyseur, mais aussi des propriétés physico-chimiques en étudiant la structure et la texture des catalyseurs usés et une études des sites acides en présence d'eau et en température. L'évolution de sites acides a été mesurée par FTIR in situ sous flux continu de NH3 et H2O. Les éventuelles compétitions d'adsorption entre H2O et NH3 mais aussi entre H2O et le réactif ont été estimées par la mesure des chaleurs d'adsorptions de ces espèces. Des oxydes d'intérêt (SnO2/SiO2, WO3/SiO2, TiO2/SiO2 et H4SiW12O40/SiO2) ont été synthétisés. Ces oxydes ont été caractérisés finement, notamment au niveau de leur acidité (utilisation de quatre molécules sondes différentes)The use of biomass to obtain platforms molecules such as olefins for the polymer industry, require an adaptation of the catalysts already used in petrochemical processing for the conversion of highly hydrated compounds. During this project we developed a method for acid catalysts characterization in the presence of water and in reaction conditions. This method combines an analysis of catalytic properties by studying the effect of water on parameters such as contact time, temperature, or aging of the catalyst, but also of physicochemical properties in studying the structure and texture of spent catalysts and a study of the acid sites in the presence of water and temperature. The acid sites evolution of was measured by FTIR in situ under continuous flow of NH3 and H2O. The possible competition of adsorption between H2O and NH3 but also between H2O and the reactant were estimated by measuring the heat of adsorption of these species. Oxides of interest (SnO2 / SiO2, WO3/SiO2, TiO2/SiO2 and H4SiW12O40 / SiO 2) were synthesized. These oxides have been finely characterized, particularly in terms of their acidity (using four different probes molecules)
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Evans, Christopher. "Episode hydrochemistry of low-order streams in three regions of the northeast United States." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320832.
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Mustafa, Akhmad Biological Earth & Environmental Sciences Faculty of Science UNSW. "Improving acid sulfate soils for brackish water aquaculture ponds in South Sulawesi, Indonesia." Awarded by:University of New South Wales. Biological, Earth & Environmental Sciences, 2007. http://handle.unsw.edu.au/1959.4/40619.
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Brackish water aquaculture is one of the largest coastal industries in Indonesia. This farming system involves the construction of ponds m coastal sediments. Many ponds in Indonesia have been abandoned due to past development of ponds in acid 8ulfate soils (ASS); these soils produce sulfuric acid through the oxidation of pyrite du ring and after the sediments have been excavated. The soils also contain elevated concentrations of metal such as iron and aluminium which are harmful to farmed fish and shrimp. Acidification of pond soil causes recurrent fish and shrimp mortalities, poor growth rate in fish and shrimp, soft shell syndrome in shrimp and low plankton densities, Pond maintenance costs in ASS are also significantly higher than non-ASS ponds. There are over 6.7 million ha of ASS In Indonesia of which 35% has been developed for brackish water aquaculture. This study developed and trialled methods of soil remediation to restore abandoned ASS-affected ponds. The main objective was to develop methods at remediation that were scientifically sound but also practical and inexpensive for farmers. The research involved characterising, in detail, the chemical and physical properties of ponds soil followed by laboratory-based experiments to improve soil properties. The results of laboratory trials were the basis for large-scale field experiments to test soil remediation strategies. The study showed that pond bottoms could be improved by forced oxidation, flooding and water exchange followed by Iiming and fertilising. Up to 500% increases in productivity were achieved by this method and soils conditions Improved significantly. A further twofold productivity increase was achieved by an integrated liming method in which lime is added to rebuilt or new dykes in layers. A juvenile shrimp production system was developed for ponds that were too severely degraded or costly to remediate. The research developed methods of preventing metal toxicity in Juvenile shrimp. The study showed that aquaculture ponds built in ASS could be remediated and returned to viable production systems. Importantly, the study has developed a more detailed understanding of chemical properties In ASS-affected ponds.
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Furuta, Hitoshi. "Rheological Properties and Functions of Water-soluble Soybean Polysaccharides Extracted under Acidic Conditions." Kyoto University, 2001. http://hdl.handle.net/2433/150362.
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LAVANDIER, MARIA ISABEL SPITZ ARGOLO. "ADSORPTION OF AMINO ACIDS BY LANGMUIR FILMS OF STEARIC ACID AT THE AIR-WATER INTERFACE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25137@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Aerossóis na troposfera influenciam o clima da Terra. A habilidade dos aerossóis de ativarem ou agirem como um núcleo de condensação de nuvens induzindo a transformação em uma gota de chuva depende de suas propriedades físico-químicas. Nessa dissertação, filmes mistos de Langmuir de ácido esteárico e aminoácidos são utilizados como modelos para a superfície de partículas de aerossóis atmosféricos. Os aminoácidos utilizados nos experimentos foram: L-Fenilalanina, L-Triptofano, L-Leucina, L-Isoleucina, L-Metionina, L-Lisina e L-Histidina, escolhidos devido às suas diferentes características de hidrofobicidade e de solubilidade em água, além de possuírem diferentes grupos R, em termos de polaridade. O presente estudo teve como objetivo compreender como os aminoácidos afetam a pressão de superfície (pi) e o potencial de superfície ( delta V) dos filmes de Langmuir de ácido esteárico na interface ar-solução aquosa, induzindo mudanças morfológicas nos mesmos. A caracterização dos filmes foi realizada por meio de experimentos de pressão de superfície e de potencial de superfície dos filmes mistos, que foram realizados em uma cuba de Langmuir minimicro acoplada a uma balança de Wilhelmy e com um sensor de potencial de superfície. De acordo com os resultados obtidos nos experimentos de pressão de superfície e de potencial de superfície, observou-se que a presença desses aminoácidos em filmes de ácido esteárico provocou diminuição da pressão de colapso do filme de ácido esteárico. Nos filmes formados com L-Fenilalanina e L-Lisina foi observada histerese em todas as compressões. L-Leucina, L-Isoleucina L-Histidina, L-Metionina e L-Triptofano não apresentaram histerese.
Aerosols in the troposphere influence the Earth s climate. The ability of aerosols to activate or act as a cloud condensation nucleus inducing the transformation into a raindrop depends on their physicochemical properties. In this dissertation, mixed Langmuir films of stearic acid and amino acids are used as templates to the surface of atmospheric aerosol particles. The amino acids used in the experiments were: L-Phenylalanine, L-Tryptophan, L-Leucine, L-Isoleucine, L-Methionine, L-Lysine and L-Histidine. They were chosen due to their different characteristics of hydrophobicity, water solubility, and polarity. This study aimed to understand how amino acids affect the surface pressure (pi) and the surface potential (delta V) of Langmuir films of stearic acid in aqueous solution-air interface, inducing morphological changes. The characterization of the films was performed by experiments of surface pressure and surface potential of the mixed film, which were carried out in a Langmuir minimicro trough coupled to a Wilhelmy balance and a surface potential sensor. According to the results obtained in the surface potential and surface pressure experiments, it was observed that the presence of these amino acids stearic acid film decreases the collapse pressure of the stearic acid film. In the films formed with L-Phenylalanine and L-Lysine, hysteresis was observed in all compressions. On the other hand, L-Leucine, L-Isoleucine, L-Histidine, L-Methionine and L-Tryptophan showed no hysteresis.
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Lifongo, Lydia Likowo. "Decomposition of haloacetic acids in water." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268583.
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Marshall, Stewart. "The complexation of aluminium by humic acids in fresh waters." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303961.
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Bertram, Allan Kent. "Freezing of sulfuric acid-water and nitric acid-water aerosols at polar stratospheric temperatures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0015/NQ38220.pdf.
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Collins, Simon. "Branchial toxicity of aluminium in soft acidic water in the brown trout, Salmo trutta L." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364458.
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Ke, Hongwei. "Density functional theory studies on glycine conformers and glycine-water complexes /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202009%20KE.
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Evens, Roger. "A seasonal study of amino acids in marine and estuarine waters." Thesis, University of Plymouth, 1986. http://hdl.handle.net/10026.1/2110.
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The fluram method for the analysis of amino acids was modified for use in sea and estuarine waters. No evidence for environmental coprecipitation of amino acids was found and any possible removal process from the Tamar estuary was most likely to be by some different mechanism. An HPLC method for the analysis of amino acids in natural waters suitable for shipboard use was developed. The method was used to determine the seasonal variation of amino nitrogen in coastal and estuarine waters in order to test the hypothesis that phytoplankton could use such compounds as a source of nutrient nitrogen when nitrate was absent. The levels found were generally an order of magnitude higher than those previously reported. This work has gone some way in accounting for some of the previously unidentified fraction of the total dissolved nitrogen in coastal waters. Similarities of amino acid spectra between coastal and estuarine waters were found and the dominant acids were serine, glycine tyrosine and ornithine. Tyrosine occurred very erratically. The patchy distribution, seasonal variation and levels of the dissolved free amino acids in coastal and estuarine waters may support the theory that phytoplankton use them as a source of nutrient nitrogen. Whilst it was not possible to show that the hypothesis was true it was considered likely that at least some amino acids might sometimes be utilised as nutrient nitrogen.
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Qi, Yinan. "Monochloramination : fecal coliform inactivation and haloacetic acid formation /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202003%20QI.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 118-129). Also available in electronic version. Access restricted to campus users.
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Dahl, O. (Olli). "Evaporation of acidic effluent from kraft pulp bleaching, reuse of the condensate and further processing of the concentrate." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514252098.
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Abstract
Environmental concern and tighter public regulations have created new pressures to reduce effluent loading from kraft pulp bleaching during the past decades. This trend has forced both pulp mills and the related engineering industries to develop and optimise equipment for the pulping processes which fulfils these demands. New pulp washers and washing systems connected with the introduction of new oxygen-based reagents have in particular provided considerably improved tools for reusing process water and thereby essentially reducing effluent discharge or even allowing the implementation of a totally closed water circulation system in kraft pulp bleaching.
This study was performed mainly on a laboratory scale at the University of Oulu, but some pilot-scale tests were also performed to confirm the findings of the laboratory-scale evaporation test. Another aim of the pilot-scale tests was to produce enough concentrate for further processing. Conditions were strictly controlled in all the experiments in order to ensure that conclusions could be reached regarding the phenomena examined.
The results reported here indicate that the amounts of transition metal ions such as iron, copper or manganese in the process water or water to be recirculated should be kept as low as possible during chlorine dioxide or peracetic acid bleaching, as even a small amount (<<5 ppm) markedly reduced pulp quality and increased reagent consumption. The results also show that evaporation can be used as a method for purifying acidic effluent from both chlorine dioxide and peracetic acid bleaching, and that the resulting condensates were free of transition metals and clean enough for reuse in both bleaching processes. The purity of the condensates was further improved by neutralising the feed pH of the acidic effluents from the bleach plant before evaporation. The results also indicate that the chloride ions in the concentrate arising from evaporation of the acidic effluent from chlorine dioxide bleaching can be removed by a combined acidification/re-evaporation system.
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Snyder, Jamie Christine. "Virus dynamics, archaeal populations, and water chemistry of Three Acidic Hot Springs in Yellowstone National Park." Diss., Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/snyder/SnyderJ0505.pdf.
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Few viruses from Archaea have been described and only a limited number have been characterized in molecular detail. Most hyperthermophilic viruses isolated from the archaeal sub-domain Crenarchaeota belong to the Sulfolobales family. We have focused on the isolation and analysis of viruses replicating in Sulfolobus. Sulfolobus is an acidophilic hyperthermophile that lives optimally at 80°C and pH 3. The SSVs (Sulfolobus spindle-shaped viruses) are the viruses most commonly isolated from thermal acidic areas around the world. SSVs are dsDNA spindle-shaped viruses with genomes of approximately 15kb. They are also the predominant virus isolated from samples collected in Yellowstone National Park (YNP). The SIRVs (Sulfolobus islandicus rodshaped viruses) are also commonly isolated from YNP. These viruses have linear dsDNA genomes of approximately 33kb. I have used these two viruses to investigate the interaction of time and viral population dynamics. For a comparison between geographically isolated acidic hot springs, we chose to study three sites in YNP. These three sites were monitored continuously for changes in virus populations, archaeal host populations, and water chemistry. Each monitor site was chemically unique, but the water chemistry did not significantly change over time. The archaeal population in each of the three hot springs was unique and was found to slowly change over time. We have discovered that although there can be a substantial change in viral population structures in between the collection of samples, it does not seem to be correlated with a changing environmental parameter. There also appears to be a strong culturing bias present in the SSVs when we compare the virus population monitored directly from the environment to the viruses isolated from an enrichment culture established from a particular hot spring. A long term goal is to contribute to the understanding of the relationships between time and resident viral populations within hot spring environments. We hope this work will contribute a further understanding of life in extreme environments.
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Fotovat, Amir. "Chemistry of indigenous Zn and Cu in the soil-water system : alkaline sodic and acidic soils." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phf761.pdf.
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Copies of author's previously published articles inserted. Bibliography: leaves 195-230. In this study the soil aqueous phase chemistry of Zn and Cu in alkaline sodic soils are investigated. The chemistry of trace metal ions at indigenous concentrations in alkaline sodic soils are reported. Metal ions at low concentrations are measured by the graphite furnace atomic absorption spectrometry (GFAAS) technique.
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Bou-Saleh, Ziad. "Nickel-based 3D electrocatalyst layers for production of hydrogen by water electrolysis in an acidic medium." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112559.
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This thesis discusses results on the development of three-dimensional (3D) Ni-based electrocatalytic layers for hydrogen production by water electrolysis in an acidic medium. This is of relevance to the development of polymer-electrolyte-membrane (PEM) hydrogen generators, which are promising hydrogen production systems suitable for both residential and industrial applications.It was demonstrated that patterning of a glassy carbon electrode substrate with a 3D polyaniline (PANI) matrix is a convenient way of increasing the electrocatalytically active surface area of electrodeposited Ni, and hence its apparent electrocatalytic activity. The optimized PANI/Ni electrocatalyst layer showed a significantly higher activity in the hydrogen evolution reaction (HER) then a commercially available Ni-plate surface (control surface).
It was also demonstrated that it is possible to produce a Ni-based HER electrocatalyst layer by synthesizing Ni nanoparticles and supporting them on Vulcan carbon. This electrocatalyst also offered a significantly higher electrocatalytic activity in the HER then the control surface, but lower then the optimized PANI/Ni electrocatalyst.
The electrocatalytic activity of the optimized PANI/Ni layer was also compared to the activity of a 3D catalyst produced by electro-coating a porous reticulated vitreous carbon (RVC) substrate with Ni. This electrocatalyst showed the highest HER electrocatalytic activity among the investigated layers when tested under potentiodynamic polarization conditions. However, under the potentiostatic conditions, the optimized PANI/Ni layer showed the highest electrocatalytic activity.
The mechanisms and kinetics of the HER on the produced electrocatalysts was also investigated, as well as the electrocatalyst layers' surface morphology and crystalline structure.
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Roman, Ramirez Luis Antonio. "Vapour-liquid equilibria of acetic acid + water and propanoic acid + water : experimental measurement and thermodynamic modelling." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6009/.
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Vapour – liquid equilibria were measured for the acetic acid + water and the propanoic acid + water systems, in the temperature range of 412.6 to 483.2 K and pressures of 1.87 to 19.38 bar, over the entire range of concentrations. An experimental apparatus based on the static-analytical method with sampling of both phases was used with quantitative analysis by GC. A new experimental technique comprising positron emission particle tracking (PEPT) was developed and applied for the determination phase compositions and molar volumes for the acetic acid + water system at 412.6 K. The Peng-Robinson (PR), the Cubic Plus Association (CPA), the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) and the PC-polar-SAFT (PCP-SAFT) equations modelled the data. The 1A and 2B association schemes for propanoic acid and the 2B, 3B and 4C for water, were evaluated. In CPA, the ECR and CR1 combining rules were also tested. A single binary interaction parameter was used in all models. PCP-SAFT presented higher predictive and correlative capabilities when the organic acid was modelled as 1A and water as 2B. The best association combination among CPA and PC-SAFT was 2B and 4C for the acid and water, respectively. CR1 accounted for lower errors in predictive mode while ECR in correlative mode. CPA performance was intermediate between the PC-SAFT and PCP-SAFT models and the PR equation. PR predictions were rather poor but correlations were better than those of CPA, at the expense of a larger binary interaction parameter.
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Chambon, Flora. "Transformation de la cellulose par catalyse hétérogène." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00829774.
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La cellulose, bio-polymère composé d'unités glucose, est un composé largement disponible au sein de la biomasse lignocellulosique. Sa dépolymérisation sélective en synthons se heurte cependant à sa forte résistance aux transformations chimiques du fait de sa structure semi-cristalline. L'objectif de la thèse est d'étudier la transformation de la cellulose par catalyse hétérogène. Il a été montré qu'une dépolymérisation partielle de la cellulose en milieu aqueux était promue par les protons issus de l'autoprotolyse de l'eau à 190°C. L'ajout d'un catalyseur solide ayant une acidité de BrØnsted forte dans le milieu réactionnel s'est révélé peu influent sur la conversion de la cellulose. En revanche, la présence de catalyseurs solides possédant une acidité de Lewis forte augmente significativement la conversion de la cellulose en formant sélectivement de l'acide lactique. Cette orientation sélective de la réaction est attribuée à l'aptitude des sites acides de Lewis à coordiner les oligosaccharides solubilisés. L'ajout d'une fonction métallique (Pt) sur un acide de Lewis solide augmente aussi significativement la conversion de la cellulose, en produisant sélectivement de l'acétol et du propylène glycol. La fonction métallique, sous atmosphère d'hydrogène, ne se limite pas à l'hydrogénation des produits finaux mais pourrait aussi intervenir dans des étapes de transfert d'hydrures et de génération de protons. Une conversion efficace de la cellulose résulte ainsi d'une action combinée des protons issus du milieu aqueux générant des oligosaccharides et des sites actifs des catalyseurs hétérogènes bifonctionnels métal-acide.
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Dalton, Catherine Phillippa. "A palaeolimnological investigation of acidity in humic lake waters in Connemara, western Ireland." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393109.
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Wang, Rongchun. "Degradation Kinetics of Uronic Acids in Subcritical Water." Kyoto University, 2011. http://hdl.handle.net/2433/142316.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第16118号
農博第1854号
新制||農||988(附属図書館)
学位論文||H23||N4588(農学部図書室)
28697
京都大学大学院農学研究科食品生物科学専攻
(主査)教授 安達 修二, 教授 北畠 直文, 教授 入江 一浩
学位規則第4条第1項該当
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Hunt, Amelia Phryne. "The ecology of epilithic biofilms in small acidic streams and their role in the biogeochemical cycling of trace metals." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266889.
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Pham, Huynh Anh. "The dynamics of microbial ferric and sulfate reduction in acidic mine lake sediments and their impact on water quality." University of Western Australia. School of Environmental Systems Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0004.
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[Truncated abstract] Acidic mine lakes are formed as a result of the oxidation and dissolution of metal sulfide minerals and are primarily characterized by low pH values of 2 4. Many strategies for the bioremediation of acidic mine lakes depend on the alkalinity generation capabilities of microbial ferric and/or sulfate reducing bacteria. However nearly all mine lakes are oligotrophic, with very low concentrations of available organic carbon and nutrients; all required for healthy microbial growth. There is also an unusual class of mine lakes characterized by low concentrations of organic carbon and also very low concentrations of dissolved iron and sulfate. Our ability to promote microbial activity in these systems is especially challenging. This study focuses on one of these systems, Lake Kepwari, a coal mine lake in Western Australia. Numerical modeling of remediation strategies is an efficient way of testing scenarios prior to expensive in-field trials. However such modeling relies on good descriptions of microbial processes, including kinetic parameterizations of ferric and sulfate reduction. There has been little research to date on the study of kinetic parameterizations of the chemical and biological alkalinity generation in acidic mine lakes. The objectives of this thesis were to investigate the viability of microbial ferric and sulfate reduction in an ultraoligotrophic, acidic mine lake, to assess the impact of these microbial processes on water quality and to parameterize the Dual Monod kinetics of neutralization under dual limitation conditions. Molecular analyses including most probable number, DNA extraction, polymerase chain reaction, polymerase chain reaction denaturing gradient gel electrophoresis were used to examine the microbial communities in the lake sediments. ... The Monod maximum specific microbial growth rates with respect to dissolved organic carbon and ferric, and as determined in batch experiments, were 0.07 ± 0.01 and 0.048 ± 0.02 day-1, respectively, and their corresponding Monod half saturation constants and were 14.37 and 5.6 mmol L-1. The Monod maximum consumption rates under ferric and OC limitation were also estimated. The Monod maximum specific microbial growth rates with respect to dissolved organic carbon and sulfate, , and were 0.05 ± 0.01, 0.08 ± 0.01 and 0.07 ± 0.02 day-1, respectively, and their corresponding Monod half saturation constants, and were 75.5, 131.8 and 10.2 mmol L-1. The Monod maximum consumption rates under sulfate and OC limitation were also estimated. The results of this study suggest that strategies for the remediation of ultraoligotrophic, acidic mine lakes may rely on microbial ferric and sulfate reduction, however additions of both organic carbon and sulfate/ferric are essential. These results can be immediately applied to mesocosm studies in outdoor enclosures and to the management of acidic mine lakes. Furthermore, this thesis has provided a new, valuable understanding on the Dual Monod kinetic parameterizations of neutralization for an ultraoligotrophic, acidic mine lake environment. These parameterizations are essential for the lake ecological models that will be used to investigate remediation scenarios for acidic mine lakes.
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Guan, Xiaohong. "Adsorption of phosphates and organic acids on aluminum hydroxide in aquatic environment : mechanisms and interactions /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20GUAN.
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Shavorskiy, Audrey. "chemistry of amino acids at the water-metal interfaces." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529971.
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Vereskuns, Gastons. "Chlorinated fatty acids in freshwater fish and some biological effects of dichlorostearic acid /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5717-3.pdf.
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van, Schaik Joris W. J. "Binding of metals to macromolecular organic acids in natural waters : does organic matter? /." Uppsala : Department of Soil and Environment, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200872.pdf.
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Wenger, Delphine. "Acid and Base Behaviour in Water Clusters." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-260239.
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MITSUYA, RENATA TOMOE. "COOLING WATER BIOCIDAL TREATMENT USING PERACETIC ACID." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36171@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
O objetivo deste estudo foi avaliar o efeito biocida do ácido peracético (APA) em águas de sistemas de resfriamento, de forma a buscar alternativas ao uso do cloro, que é corrosivo e reage com a matéria orgânica natural ou sintética presentes na água, formando subprodutos tóxicos. Para atingir este objetivo, experimentos utilizando amostras de água retiradas da bacia de uma torre de resfriamento de uma indústria química foram realizados. Ensaios foram executados utilizando-se uma solução comercial de APA, mantendo-se concentrações do biocida em 1,0 mgL-1 e 2,0 mgL-1 em pH 8,0 e 8,8. Cada condição de estudo foi monitorada ao longo de 5 dias, e contagens de bactérias heterotróficas mesófilas totais foram realizadas tanto antes da aplicação do biocida como em diferentes tempos de contato do biocida com a microbiota natural da água. Os tempos de contato monitorados foram de 5 min, além de 1, 2 e 4 h por dia considerando a aplicação do biocida em períodos totais de 4 h por dia. Com esta metodologia foi possível concluir que as duas dosagens aplicadas foram eficientes no combate aos microrganismos presentes naturalmente nas amostras de água, nos dois valores de pH estudados. A partir de uma carga microbiana natural da água de 106 a 107 UFC/mL, após o tratamento houve uma redução para contagens de no máximo de 104 UFC/mL em todos os experimentos, limite máximo esse adotado pelas indústrias para carga microbiana em águas de sistemas de resfriamento, entretanto, houve maior eficiência, cerca de 10 vezes maior, quando 2,0 mgL-1 de APA foi aplicado. Além disso, em pH 8,0 a ação do biocida também foi superior em 10 vezes em detrimento ao pH 8,8 para a mesma concentração de APA.
The purpose of this study was to evaluate the biocidal effect of peracetic acid (PAA) in cooling water, in order to find alternatives to the use of chlorine, which is corrosive and reacts with natural and synthetic organic matter present in water, forming toxic byproducts. To achieve this goal, experiments using water samples taken from a basin of a chemical industry cooling tower were conducted. Experiments were performed using a commercial PAA solution, with concentrations of 1,0 mgL-1 and 2,0 mgL-1 and pH 8,0 and 8,8. Each study condition was monitored for 5 days and total mesophilic heterotrophic bacteria counts were made without biocide and after different contact times of the biocide and microorganisms present in water. The contact times were 5 min, and 1, 2 and 4 h per day, considering the application of the biocide in total periods of 4 h per day. This methodology has allowed concluding that two dosages applied were efficient in controlling microorganisms at the two pH values. From a water natural microbial count of 106 to 107 UFC/mL, after treatment there was a reduction to maximum counts to 104 UFC/mL in all experiments, that being the upper limit adopted by industries for microorganisms in cooling water systems. However, the results were 10 times more efficient when 2,0 mgL-1 of PAA were applied. In addition, at pH 8,0 the biocidal action was 10 times higher in comparison to pH 8,8 for the same PAA concentration.
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Le, Gall Anne Christine. "Determination of glutathione and folic acid in natural waters using voltammetry." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317001.
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Savis, Camilla Margaret. "Effects of copper and acidic mine drainage on sediment and water quality in Keswick Reservoir, Shasta County, California /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Blasco, Ahicart Marta. "Earth Abundant Materials for Electrocatalytic Water Oxidation: Enhancing Efficiency and Robust Performance in Acidic, Neutral and Alkaline Media." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/457706.
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En aquesta tesi doctoral presentem diferents estratègies per al desenvolupament d’elèctrodes, basats en elements abundants en l’escorça terrestre, actius en l’oxidació electrocatalítica de l’aigua en diferents medis. En primer lloc, hem precipitat el clúster [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16− (Co9) amb Ba2+ i Cs+ per obtindre sals insolubles en aigua que poden ser mesclades amb una matriu conductora, com la pasta de carboni. Els elèctrodes de BaCo9 presenten una activitat excel·lent en medi àcid, combinada amb 100% d’eficiència Faradàica i estabilitat a llarg termini. En segon lloc, el clúster nonanuclear Co9 també ha estat combinat amb un polímer conductor (polipirrol) per obtenir elèctrodes híbrids orgànic-inorgànics actius en l’oxidació electrocatalítica de l’aigua en medi neutre. Aquest mètode de processament és molt interessant, ja que proporciona elèctrodes versàtils a partir de materials barats i abundants. Finalment, hem analitzat òxids binaris i ternaris amb diferent composició (Ni, Zn, Fe i Cr) per millorar l’activitat dels òxids metàl·lics front l’oxidació catalítica d’aigua en medi bàsic. Aquells compostos amb fase espinela i -Fe2O3 hematita presenten elevada eficiència combinada amb bona estabilitat a llarg termini.En la presente tesis doctoral presentamos diferentes estrategias para desarrollar electrodos, basados en elementos abundantes en la corteza terrestre, activos en la oxidación electrocatalítica del agua en diferentes medios. En primer lugar, hemos precipitado el clúster [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16− (Co9) con Ba2+ i Cs+ para obtener sales insolubles en agua que pueden ser mezcladas con una matriz conductora, como la pasta de carbono. Los electrodos de BaCo9 presentan una actividad excelente en medio ácido, combinada con 100% de eficiencia Faradaica y estabilidad a largo plazo. En segundo lugar, el clúster nonanuclear Co9 también ha sido combinado con un polímero conductor (polipirrol) para obtener electrodos híbridos orgánico-inorgánicos activos en la oxidación electrocataítica del agua en medio neutro. Este método de procesamiento es muy interesante, ya que proporciona electrodos versátiles a partir de materiales baratos y abundantes. Finalmente, hemos analizado óxidos binarios y ternarios con diferente composición (Ni, Zn, Fe i Cr) para mejorar la actividad de los óxidos metálicos frente a la oxidación electrocatalítica del agua en medio básico. Los compuestos con fase espinela y -Fe2O3 hematita presentan elevada eficiencia combinada con buena estabilidad a largo plazo.
In this Doctoral Thesis, different approaches to develop suitable working anodes based on Earth abundant metals for the electrocatalytic water oxidation reaction in different media have been presented. We have precipitated the nonanuclear cobalt cluster [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16− (Co9) with Ba2+ and Cs+ to obtain water-insoluble salts that can be blended with a solid-state matrix, such as carbon paste. The BaCo9 have shown excellent and unparalleled performance for the electrocatalytic water oxidation in acidic media, yielding 100% Faradaic efficiency matched with good long-term stability. We have also incorporated the homogeneous Co9 POM into a conducting polymer matrix (i. e. polypyrrole) to obtain organic-inorganic anodes active in electrocatalytic water oxidation reaction in neutral conditions. This interesting processing approach has yielded versatile electrodes obtained from low cost and available raw materials. Finally, we have screened binary and ternary mixed oxide compositions, based on Ni, Zn, Fe and Cr, for the enhancement of electrocatalytic water oxidation in alkaline media. Cubic spinel phases, as well as, -Fe2O3 hematite have shown best efficiency combined with good long-term stability under working conditions.
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Jage, Christopher Raymond. "Water Quality Based Design Guidelines for Successive Alkalinity-Producing Systems Used in the Treatment of Acidic Mine Drainage." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31390.
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Successive Alkalinity-Producing Systems (SAPS) have proven to be a viable alternative to chemical treatment for renovating acidic mine drainage (AMD). The lack of water quality based design guidelines, however, is believed to be a cause of the variability of SAPS performance in the field. This study monitored eight SAPS systems for the purpose of determining the effect of influent water quality and system design on system performance. Monthly water quality data were obtained for each system over periods ranging from 3 to 5 years. All systems demonstrated an ability to generate alkalinity and/or neutralize acidity. These systems revealed significant correlations between net alkalinity production and log residence time (r = 0.7414), influent total iron (r = 0.7357), and influent non-manganese acidity (r = 0.6919). From these relationships, a calibrated model was developed for predicting SAPS net alkalinity generation. As a compliment to the field study, a series of laboratory-scale SAPS columns were studied for a period of 12 months to examine the effect of residence time on system performance and to monitor the internal changes in water quality. The columns were operated at residence times of 17, 30, 60 hours with three replicates each and were subject to ambient temperature fluctuations. Data revealed that systems with residence times below 25 hours in the organic layer were unable to adequately reduce dissolved oxygen concentrations in the organic layer to prevent limestone armoring. The results of this study suggest water quality based guidelines for designing SAPS systems.Master of Science