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Tesi sul tema "Hydrogen peroxide"
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1
Samanta, C. "Direct oxidation of hydrogen to hydrogen peroxide". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2423.
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2
Djerdjouri, Nour-Eddine. "Hydrogen peroxide delignification in a biomimetic system based on manganese peroxidase". Diss., Available online, Georgia Institute of Technology, 2005, 2003. http://etd.gatech.edu/theses/available/ipstetd-1017/.
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3
Barley, Sarah. "Miniaturisation of a hydrogen peroxide thruster". Thesis, University of Surrey, 2006. http://epubs.surrey.ac.uk/842697/.
Testo completoAbstract (sommario):
A continuing demand exists to develop the capabilities of nanosatellites. A key element limiting the range of nanosatellite applications is the accommodation of a propulsion system. This research investigated this need and considered the miniaturisation of a monopropellant thruster. A literature review considered all aspects of micropropulsion together with enabling technologies. Assessment of present micropropulsion developments revealed that few would conform to the nanosatellite constraints. In addition the complexities associated with the miniaturisation of a propulsion system such as the modification of fluid flow, were highlighted. A review of the possible applications of a propulsion enhanced nanosatellite resulted in the creation of an inspection mission scenario. Assessment of present micropropulsion developments revealed none could fulfil the mission requirements, but a miniaturised chemical propulsion could. This led to the initiation of research to miniaturise a monopropellant thruster that would meet the mission requirements within the platform constraints. Hydrogen peroxide was selected as the propellant as it is considered to be a Green, non-toxic and non-carcinogenic propellant. The effect of scaling on the thermal characteristics of the thruster was evaluated using numerical models, which considered the effect of chamber wall thickness. It was concluded that a thin walled chamber should be combined with a heat-shield to allow radiated heat to be reflected back towards the decomposition chamber. The options available for the manufacture of a micropropulsion system were considered with respect to machining accuracy, materials and cost. There are two main options: Micro-Electro-Mechanical Systems (MEMS) technologies or micro conventional precision machining methods. It was concluded that at present the use of the latter was preferred as the level of machining accuracy is higher and conventional materials can be used. Following these analyses the detailed miniaturisation of the monopropellant thruster began, with a focus upon two major components: the decomposition chamber and the exhaust nozzle. The use of hydrogen peroxide as a rocket monopropellant was prevalent in the 1960's. Since then its use has waned in favour of other monopropellants such as hydrazine, which exhibit higher performance and improved storage characteristics. At that time significant research was conducted into the performance of hydrogen peroxide, but its use for low thrust applications was not considered. An analysis of available empirical data was conducted to determine the optimal configuration of a decomposition chamber in terms of the geometry of the decomposition chamber as well as the morphology of the catalyst bed. Two different catalyst morphologies were considered: a monolithic catalyst bed and a compressed powder catalyst bed. The monolithic morphology was based upon a ceramic foam substrate coated with a manganese oxide catalyst. Overall it generated good decomposition characteristics, but suffered from severe internal structural degradation. A compressed silver powder catalyst generated excellent decomposition characteristics and enabled the effect of catalyst bed length to be investigated as a function of decomposition chamber diameter. The results from these tests indicate that a compressed silver powder catalyst bed is a suitable alternative to silver gauzes for use in small diameter decomposition chambers, in addition the results showed that an optimal mass flow rate exists for each length of catalyst bed and a shorter bed is preferred due to thermal characteristics.
4
Gunathilagan, Suthahari. "Metalloporphyrin-catalysed epoxidation using hydrogen peroxide". Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/800040/.
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5
Cosgrove, Martin. "Electrochemical approaches to hydrogen peroxide monitoring". Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238189.
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6
Shaw, Jacqueline. "Epoxidation of alkenes by hydrogen peroxide". Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317247.
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7
PERES, FERNANDO ANTONIO SERRAPIO. "COOLING WATER TREATMENT USING HYDROGEN PEROXIDE". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8889@1.
Testo completoAbstract (sommario):
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOPERÓXIDOS DO BRASIL
O tratamento de águas de resfriamento normalmente é feito com a adição de cloro, porém este produto apresenta algumas desvantagens em sua aplicação. Como alternativa ao cloro, algumas indústrias no Brasil e no exterior estão começando a utilizar outros biocidas, dentre estes o peróxido de hidrogênio, um poderoso oxidante que apresenta forte ação biocida. O objetivo deste trabalho foi comparar a eficiência do cloro e do peróxido de hidrogênio como biocidas em diferentes condições, através de testes em água da torre de resfriamento de uma indústria siderúrgica localizada no Rio de Janeiro. A contaminação microbiológica desta água foi medida sem a adição dos biocidas e com a adição de cloro e peróxido de hidrogênio, permitindo assim comparar o desempenho destas substâncias no combate aos grupos bacterianos presentes na amostra. Foi realizado também um estudo sobre o efeito corrosivo destas substâncias através de testes de corrosão em aço carbono 1020, que permitiram avaliar a taxa de corrosão por perda de massa provocada pela aplicação destes produtos na água. Os resultados mostraram que o peróxido de hidrogênio possui uma ação biocida satisfatória para aplicações em águas de resfriamento. Foi constatado que o efeito biocida do peróxido de hidrogênio é mais limitado do que o cloro e que sua eficiência depende do tempo de contato e pode ser afetada pela presença de impurezas dissolvidas na água. Os ensaios de corrosão revelaram que o peróxido de hidrogênio provoca um efeito corrosivo comparável ao do cloro no material testado.
Cooling water treatment generally is made with the addition of chlorine, although it´s application has some disadvantages. There is an active development in Brazil and other countries to use alternative chemical disinfectants in place of chlorine, such as hydrogen peroxide, a powerful oxidant which is known for its high biocidal efficiency. The aim of this research is to study the effectiveness of hydrogen peroxide as a disinfectant compared to chlorine in different operational conditions. The experiments were carried out using an water sample from a cooling water system of a steelmaking plant in the city of Rio de Janeiro. The microbial contamination of this water sample was measured without adding any kind of disinfectant. After that, water sample was treated by adding hydrogen peroxide and chlorine, in order to compare and evaluate the efficiency of the two biocides to control bacterial growth in water. Besides microbiological tests, experiments were conducted to compare the degree of corrosion caused by the addition of hydrogen peroxide and chlorine in water. The experimental methodology employed 1020 carbon steel specimens and corrosion rates were measured by weight loss determination after the period of exposure. The results showed that the application of hydrogen peroxide leads to satisfactory bacterial control. However, compared to chlorine, hydrogen peroxide is a rather poor disinfectant. The efficiency of hydrogen peroxide depends on reaction time and it is affected by dissolved polluants in water. Evaluation of corrosion rates showed that hydrogen peroxide causes basically the same corrosion rates than chlorine.
8
Qiu, Zhiping. "Improvement in hydrogen peroxide bleaching by decreasing manganese-induced peroxide decomposition". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0034/MQ65515.pdf.
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9
Been, Jantje. "Titanium corrosion in alkaline hydrogen peroxide environments". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/NQ34511.pdf.
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10
Dorward, Ann M. "Hydrogen peroxide production and autocrine proliferation control". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ66202.pdf.
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11
Woolfall, Marc P. "Novel mediators for oxidation using hydrogen peroxide". Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367254.
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12
Alvarez-Gallegos, Alberto Armando. "Applications of hydrogen peroxide in electrochemical technology". Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266663.
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13
Clapp, Philip Anthony. "Studies on the production of hydrogen peroxide". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47810.
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14
Pellinen, Riikka. "Hydrogen peroxide in inducible plant stress responses". Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/mat/bioti/vk/pellinen/.
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15
Borràs, Brull Marta. "Development of electrochemical sensors for hydrogen peroxide determination". Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/669818.
Testo completoAbstract (sommario):
La motivació principal darrera d’aquesta tesi és el desenvolupament de nous sensors (bio)químics de baix cost que puguin assentar les bases pel disseny de plataformes de detecció robustes, econòmicament assequibles, escalables i fàcils d’utilitzar. La primera estratègia es basa en la incorporació de polímers conductors per aconseguir un rendiment analític millorat i al mateix temps, unes característiques finals del dispositiu d’assequibilitat i senzillesa en el seu ús. La segona part aborda l’exploració i el desenvolupament de sensors per al diagnòstic no invasiu, amb l’objectiu de millorar la qualitat de vida dels usuaris finals.
El treball comença introduint la importància de la detecció de peròxid d’hidrogen, incloent algunes de les seves moltes aplicacions en diferents camps, i una breu descripció de l’estructura de la tesi i els objectius. A continuació es presenten alguns dels treballs més recents en la detecció de peròxid d’hidrogen utilitzant polímers conductors. La comparació del rendiment analític així com els reptes a afrontar en un futur també són descrits en la tesi. Fruit d’aquests reptes, la primera part de la tesi es basa en el desenvolupament de noves estratègies per la determinació de peròxid d’hidrogen en forma de treball experimental. La segona part enfoca el desenvolupament de sensors electroquímics basats en l’ús enzims oxidasa per la detecció de peròxid d’hidrogen com a producte de la reacció principal. A més a més, s’expliquen també els fonaments científics de les tècniques utilitzades i els principis de detecció en que es basa la tesi.La motivación principal detrás de esta tesis es el desarrollo de nuevos sensores (bio)químicos de bajo coste que puedan sentar las bases para el diseño de plataformas de detección robustas, económicamente asequibles, escalables y fáciles de usar. La primera estrategia se basa en la incorporación de polímeros conductores para conseguir un rendimiento analítico mejorado y al mismo tiempo, unas características finales del dispositivo de asequibilidad y sencillez en su uso. La segunda parte abarca la exploración y el desarrollo de sensores para el diagnóstico no invasivo, con el objetivo de mejorar la calidad de vida de los usuarios finales. El trabajo empieza introduciendo la importancia de la detección del peróxido de hidrógeno, incluyendo algunas de sus muchas aplicaciones en distintos campos, i una breve descripción de la estructura de la tesis y sus objetivos. A continuación se presentan algunos de los trabajos más recientes en la detección de peróxido de hidrógeno utilizando polímeros conductores. La comparación del rendimiento analítico así como los retos a afrontar en un futuro también se describen en la tesis. Fruto de estos retos, la primera parte de la tesis se basa en el desarrollo de nuevas estrategias para la determinación de peróxido de hidrógeno en forma de trabajo experimental. La segunda parte enfoca el desarrollo de sensores electroquímicos basados en el uso de enzimas oxidasa para la detección de peróxido de hidrógeno como producto de la reacción principal. Además, se explican también los fundamentos científicos de las técnicas usadas y los principios de detección en los que se basa la tesis.
The main motivation behind this doctoral thesis is the development of novel and low-cost (bio)chemical sensors that can set the basis to design robust, affordable, scalable and user-friendly sensing platforms. The first approach is based on the incorporation of conducting polymers to achieve enhanced analytical performance as well as desirable final device features, such as affordability and simple operation. The second part of the thesis is addressed on the exploration and development of biosensors for non-invasive diagnostics, with the aim of improving the quality of life of potential end-users. The work begins by introducing the importance of the determination of hydrogen peroxide, including some of its several applications in different fields and a brief description of the thesis structure and objectives. It continues by presenting some of the most recent works on hydrogen peroxide detection using conducting polymers. A critical comparison of the analytical performance and some of the future challenges are described. Fruit of these challenges, the first part of the thesis is based on the development of new approaches for such detection in the form of experimental work. The frame of the second part of the thesis points out the development of electrochemical sensors based on enzymes in order to determine hydrogen peroxide as a byproduct of the main oxidase reaction. In addition, some background of scientific foundation, technological methods and principles on which the work stands is also provided.
16
Forteza, Radia. "Regulation of Hydrogen Peroxide in the Human Airway". Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/173.
Testo completoAbstract (sommario):
In airway epithelia, lactoperoxidase (LPO) constitutes an important anti-microbial system to protect the host against infection and inflammation. LPO uses hydrogen peroxide and thiocyanate anion to form the biocidal compound, hypothiocyanite. The rate-limiting factor is hydrogen peroxide substrate availability. This study was conducted to identify the major source of hydrogen peroxide and to characterize its regulation in the human airway. Two homologues of the phagocytic NADPH oxidase, Duox1 and Duox2, were shown to be highly expressed and functional in human airway epithelial cells re-differentiated at the air liquid interface (ALI). Duox activity is regulated by intracellular calcium concentration via its two EF-hand motifs. A rise of intracellular calcium concentration exhibited kinetics that correlated with increase of Duox-generated hydrogen peroxide production, which was inhibited by DPI, a NADPH oxidase inhibitor. Additionally, the involvement of Duox activity in the LPO system was investigated. Bacterial products such as flagellin or inflammatory mediators were used to challenge ALI cultures. As a result, mRNAs from Duox2, LPO and DUOXA2, but not Duox1, were up-regulated in response to stimuli. This study provided new information about the regulation of the anti-microbial LPO system in innate immune host defense.
17
Winterle, James Richard, e James Richard Winterle. "Sorption Kinetics of Hydrogen Peroxide to Ice Grains". Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/626794.
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18
Penketh, P. G. "Nitrofurazone and hydrogen peroxide metabolism in Trypanosoma brucei". Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383315.
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19
Murray, Jane. "Selective oxidation of organosulfur substrates by hydrogen peroxide". Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428461.
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20
Cooper, J. M. "Electron transfer resulting from hydrogen peroxide metabolising enzymes". Thesis, Cranfield University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279323.
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21
SANTOS, NAIARA DE OLIVEIRA DOS. "ACCELERATED DEPURATION OF POLLUTED RIVERS USING HYDROGEN PEROXIDE". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26761@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Estudos prévios relacionam a ocorrência de episódios de mortandade de peixes em corpos hídricos como a Lagoa Rodrigo de Freitas (LRF) com a rápida disponibilização de espécies poluentes e nutrientes naturais na coluna d água especialmente durante altas precipitações de chuva, quando ocorre transbordo dos rios poluídos da bacia sobre a água da Lagoa, ocasionando uma demanda de oxigênio dissolvido maior do que o normal para depuração de tais espécies. Nesse contexto existe interesse em evitar episódios críticos de insuficiência de OD na água dos corpos hídricos que possam advir de tais eventos. Estudos realizados no presente trabalho tiveram como objetivo caracterizar as águas de rios da Sub-bacia hidrográfica da LRF através de DBO, COT, SST, Ptotal no canal a montante de deságue para a Lagoa em períodos de chuva e de tempo seco; e avaliar um possível tratamento que proporcione a depuração acelerada dos poluentes utilizando peróxido de hidrogênio, fornecendo oxigênio para as águas poluídas através do processo de decomposição do oxidante. Avaliaram-se diferentes dosagens de H2O2 em tempo reacional de 24h de acordo com limites de ecotoxicidade conhecidos. Testes realizados em amostras de rio coletadas em dias de baixa precipitação contendo concentrações de DBO de até 2,2 mg/L mostraram uma velocidade de decaimento de H2O2 inferior ao para amostras tanto coletadas também em dia de baixa precipitação porém com elevada DBO (24,0 mg/L), quanto para dia de alta precipitação (13,2 mm em 24 h) com relevante concentração de material orgânico. Observou-se uma dosagem suficiente de 15,0 mg/L para as amostras coletadas em baixa precipitação e alta DBO, e dosagem suficiente de 3,0 mg/L para amostras coletas em maior evento de precipitação (13,2 mm em 24 h), acima das quais, não ocorre mais aumento significativo da velocidade de decaimento da [H2O2] e também de velocidade de contribuição de OD para a água. Concluiu-se que a adição de H2O2 nas águas de rios durante eventos de poluição causados por chuvas intensas ou lançamento de esgoto pode contribuir para evitar episódios críticos de insuficiência de OD em rios poluídos por material orgânico e na pluma de poluentes que pode ser formada por transbordo dos rios para a LRF.
Previous studies have associated the occurrence of episodes of death of fish in water bodies such as the Lagoa Rodrigo de Freitas (LRF) to to the rapid availability of pollutants and natural nutrients in the water column species especially during high rain precipitation events, which occur when the rivers overflow and pollute the water of the lagoon, causing a biochemical oxygen demand higher than usual for the rate of natural depuration of the contaminating species. In this context there is interest in avoiding critical episodes DO deficiency in the water bodies that may arise from such events. Studies conducted in the present work aimed at characterizing the rivers of sub-basin of LRF through BOD, TOC, TSS, Ptotal on the canal that overflows into the lagoon in periods of rain and dry weather; and evaluate a possible treatment offering the accelerated depuration of pollutants using hydrogen peroxide, providing oxygen to the polluted water through the self-decomposition process. The study evaluated the effect of different doses H2O2 in 24 hours of reaction time according to known ecotoxicity limits. In tests on samples collected from rivers in days of little rain containing BOD concentrations up to 2.2 mg / L, H2O2 showed a decay rate lower than those of other samples also collected on days of low precipitation, but with high BOD (24, 0 mg / L), and days of high rainfall (24 hours 13.2 mm), with a significant concentration of dissolved organic contaminants. A maximum sufficient dose of 15.0 mg / L was found for the low and high samples precipitation BOD, and a maximum sufficient dose of 3.0 mg / L for most of the samples collected during the precipitation event (13.2 mm 24 hours), above which there is no significant increase over the rate of decomposition of [H2O2], and the rate of generation of DO in the water. It was concluded that the addition of H2O2 into the waters of rivers during pollution events caused by heavy rains or sewage release can help to avoid critical episodes of DO deficiency in polluted rivers by organic matter and pollutant plume that can be formed by overflow of those rivers to the LRF lagoon.
22
Jones, Ceris Ann. "Effects of hydrogen peroxide in mist on vegetation". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46847.
Testo completo
23
Atuobi, Ampadu Christiana. "Pathogen Reduction on Selected Vegetables Using Hydrogen Peroxide". Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1182285352.
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24
Liu, Chang. "Electrochemical Hydrogen Peroxide Production Via Oxygen Reduction Reaction". Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29543.
Testo completoAbstract (sommario):
Hydrogen peroxide (H2O2) is a valuable chemical with rapidly growing demand in a variety of applications. At present, industrial production of H2O2 is through an energy-intensive anthraquinone process with high production costs and environmental hazards. Recently, the reported noble-metal based catalysts such as Pd-Au alloy, using renewable electricity to generate H2O2 via two-electron transferred oxygen reduction reaction (2e–-ORR), has received much attention. However, the cost and abundance of noble metals limit such catalysts for large-scale applications. To reduce the high overpotential requirement and improve the low yield of such noble metal catalysts, developing cost-efficient catalysts with high H2O2 selectivity and activity is a challenge that must be addressed immediately. Therefore, it is of great importance to design and synthesize electrocatalysts with abundant high-performance active sites for electrochemical H2O2 synthesis. In this thesis, by using a combination of theoretical calculation and experiments, I have demonstrated some effective approaches to tune the H2O2 generation performance on a series of structure-defined systems, including columbites (MNb2O6, M = Mn, Fe, Co, Ni and Cu), a porphyrin-based covalent organic framework (COF-366-M, M = Mn, Fe, Co, Ni, Cu and Zn) and a heterogeneous molecular catalyst system (HMC). In acid, neutral or alkaline conditions, I showcase the tunable H2O2 synthesis performance and identify the optimal composition and atomistic structure for these catalytic systems, paving the foundation for practical electrochemical H2O2 synthesis.
25
Biasi, Pierdomenico. "Engineering the reaction of hydrogen peroxide direct synthesis". Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427081.
Testo completoAbstract (sommario):
Hydrogen peroxide (H2O2) is a versatile environmentally friendly oxidizing agent that has many practical applications. H2O2 has countless qualities and it is one of the world’s most important bulk inorganic chemicals. Most of the world’s H2O2 is produced by auto-oxidation process (AO). The AO process involves indirect oxidation of H2 to yield H2O2. The first commercial anthraquinone (AQ) process was operated by I.G. Farbeinindustrie in Germany during the second world war. The AO process is successfully used to produce most of the world’s H2O2 because it avoids explosive H2/O2 gas mixture.
However AO process suffers from several drawbacks, such as the use of a complex and toxic solvent system, the periodic replacement of costly quinone-derivative due to non-selective hydrogenation, the deactivation of the hydrogenation catalyst, high requirements of energy and intensive process steps for the removal of organic impurities. Also, it is known to have high capital and operating costs, thus it economically viable only for large scale productions (>4*104 tons per year). Therefore, H2O2 is produced in few locations and then transported to the customers. Transportation of H2O2 creates additional safety concerns since concentrated H2O2 can decompose explosively.
A process where H2O2 forms from the direct combination of its elements (H2 and O2) could be preferred, especially for small scale productions at the end-user site, if control of the sequential hydrogenation can be achieved, but none of the presently available processes has solved the productivity vs. safety dilemma.
Traditionally, the attention of the scientists focused on the identification of an active and particularly selective catalyst, overlooking the impact of safety and multiphase issues. Both aspects may benefit from continuous operations and suitable feeding policies, along with kinetics studies as we are currently investigating.
Three reactor set-ups were developed and realized for hydrogen peroxide direct synthesis: two of them are based on batch reactors of different volumes to perform catalytic tests and kinetics studies, and one is based on a novel trickle bed reactor (TBR).
Most of the work presented here is focused on the continuous reactor, far more attractive from an industrial perspective. In the TBR set up different catalysts were chosen to investigate H2O2 direct synthesis. A systematic study on operative conditions was performed, varying liquid and gas flow rates (contact time between liquid,gas and solid phases), changing H2/O2 ratio, investigating conditions for H2O2 decomposition and the effect of pressure. With this work very high values of selectivity were achieved (up to 90%), improving catalytic performances compared to those previously obtained in batch reactor set-ups. The best results were accomplished with a Pd and Au catalyst supported on sulfated zirconia.
Despite an extensive body of research on the direct synthesis process, very little has been published about kinetic rate expressions of the full reaction network, and in this study experimental kinetics in a batch reactor and their relative modeling are treated for the first time.Il perossido di idrogeno è un ossidante “verde” e non tossico, che non genera sottoprodotti inquinanti per l’ambiente, poiché si decompone a dare solamente acqua ed ossigeno. Il perossido di idrogeno viene utilizzato principalmente nelle cartiere come sbiancante, nell’industria tessile e metallurgica, come intermedio nella sintesi chimica, come disinfettante e additivo per detergenti, e molto altro. L’H2O2 viene attualmente prodotto con il processo dell’antrachinone, il quale necessita di numerose operazioni per la produzione e la purificazione del prodotto finale, con il conseguente elevato consumo energetico, a cui sono associati notevoli costi di esercizio, e la formazione di sottoprodotti inquinanti. La sintesi diretta di H2O2 è un’alternativa interessante, che si propone di eliminare i sottoprodotti inquinanti e ridurre drasticamente i costi di impianto e di esercizio, per produzioni su piccola scala direttamente in situ presso l’utilizzatore finale (che non è Berlusconi). In questo modo sarebbe possibile abbattere anche i costi di trasporto e i rischi ad esso connessi. Negli ultimi anni particolare attenzione è stata data al processo di sintesi diretta di acqua ossigenata, tuttavia i lavori pubblicati e brevettati vertevano per lo più sullo sviluppo di un catalizzatore che potesse avere delle caratteristiche tali da favorire la formazione di perossido di idrogeno a dispetto delle reazioni di decomposizione e idrogenazione dello stesso, anch’esse facenti parte del network di reazione. Scarso interesse è invece stato rivolto allo studio sistematico delle condizioni operative e allo sviluppo di un processo continuo. Ad esempio, lo studio in reattori batch non è stato mai approfondito con cinetiche di reazione e con lo studio degli equilibri liquido-vapore che si instaurano all’interno del sistema di reazione. In questo lavoro sono stati sviluppati e realizzati due reattori di tipo batch (di due volumi differenti) e un reattore in continuo: dei due reattori batch, uno è stato utilizzato per testare i catalizzatori e condurre studi preliminari, mentre nell’altro si sono svolti studi di cinetiche di reazione, che sono stati successivamente utilizzati per sviluppare un modello cinetico relativo all’intero network di reazioni. Il reattore continuo, invece, è un reattore a letto fisso (trickle bed reactor) in cui viene caricato il catalizzatore. Un notevole interesse dalle realtà industriali è rivolto all’operazione in continuo, per cui in questo progetto particolare attenzione è stata data allo sviluppo di un tale processo, ottimizzandone le condizioni operative per massimizzare la produzione di acqua ossigenata. Numerosi catalizzatori mono- e bi- metallici sono stati studiati, supportati su diversi materiali, sia inorganici che organici, e per ognuno di essi sono state studiate le migliori condizioni operative. Nel Capitolo 1 è presentato lo stato dell’arte della ricerca sulla sintesi diretta del perossido di idrogeno, e viene spiegato come la ricerca effettuata fin d’ora abbia posto l’attenzione sullo studio di un catalizzatore che potesse essere adatto alla sintesi diretta, trascurando però lo studio reattoristico del sistema impiegato. Nel Capitolo 2 è descritto lo sviluppo dei reattori in seguito utilizzati nella sperimentazione, ed i sistemi di analisi implementati. Vengono presentati gli schemi di impianto e gli studi preliminari condotti sia sui reattori batch, che sul reattore continuo. Il Capitolo 3 affronta temi di cinetica con la relativa modellazione. Sono stati condotti esperimenti di sintesi diretta in un reattore batch ad alta pressione, e da questi dati è stato ricavato un primo approccio di modello cinetico ancora assente in letteratura. Nel Capitolo 4 si è studiato un catalizzatore al palladio su un supporto di ceria sulfatata, con il quale sono stati condotti esperimenti di decomposizione e idrogenazione del perossido di idrogeno. Partendo da questi risultati si è svolto uno studio teso ad identificare le migliori portate di gas e di liquido per ottenere la massima produttività e la massima selettività. Un’altra condizione operativa indagata è stata la pressione ed il suo effetto sulla produzione di acqua ossigenata. Nel Capitolo 5 sono stati scelti 4 catalizzatori a base di palladio, supportati su diversi materiali inorganici. Variando le condizioni operative di sistema si è studiato il comportamento di questi catalizzatori in relazione alla produzione di H2O2 e alla loro selettività. I vari catalizzatori, a seconda del supporto, hanno proprietà differenti e le condizioni operative devono essere ottimizzate di conseguenza per ottenere il massimo rendimento sulla sintesi diretta. Il Capitolo 6 tratta lo studio di catalizzatori bimetallici a base di palladio e oro e catalizzatori a base di solo palladio. Diversi supporti inorganici sono stati utilizzati ed è stato introdotto un nuovo supporto organico. I catalizzatori sono stati confrontati tra di loro variando le condizioni operative di sistema. È stato inoltre studiato l’effetto della concentrazione di idrogeno immesso come reagente e il suo effetto sulla sintesi diretta di H2O2. Il Capitolo 7 riassume i migliori risultati ottenuti e fornisce indicazioni relativamente agli sviluppi futuri. In Appendice è fornito un approccio per la modellazione termodinamica del sistema.
26
Bostwick, Stephanie L. "Determining hydrogen peroxide exposure of employees at Company XYZ". Online version, 2002. http://www.uwstout.edu/lib/thesis/2002/2002bostwicks.pdf.
Testo completo
27
Mitchell, Michael S. "Oxidation of biological molecules with bicarbonate-activated hydrogen peroxide and the decomposition of hydrogen peroxide catalyzed by manganese(II) and bicarbonate". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004948.
Testo completo
28
Edwards, Jennifer Kelly. "Direct synthesis of hydrogen peroxide from hydrogen and oxygen over catalysts containing gold". Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/56194/.
Testo completoAbstract (sommario):
The direct synthesis of hydrogen peroxide from hydrogen and oxygen over supported gold, palladium and gold palladium catalysts was studied in a high-pressure stirred autoclave containing a stabiliser-free solvent system. The rate of H2O2 synthesis for supported Au catalysts was found to be lower than that of the Pd only catalysts. However, carbon, titania, iron oxide and alumina supported Au-Pd catalysts are significantly more active and selective for H2O2 synthesis than the monometallic catalysts. For silica supported gold-palladium catalysts, the activity was found to scale directly with palladium content and no synergy was observed with gold-palladium catalysts. Gold-palladium catalysts prepared on iron oxide, alumina and titania were all found to form core-shell structures on calcination consisting of a gold core surrounded by a palladium shell. However, on silica and activated carbon the bimetallic catalysts formed homogenous alloys. The activity and selectivity of the catalyst was found to be highly dependant on the reaction conditions employed factors such as catalyst mass, solvent composition, catalyst composition and reaction length had significant effects on the catalyst activity. Modification of the support with a dilute acid prior to metal deposition led to gold-palladium catalysts with >98% selectivity to H2O2 when compared to catalysts prepared on the unmodified support. This increase in catalytic performance corresponded to an increase in metal particle size - indicating that smaller gold-palladium catalysts are highly active and selective for the direct synthesis of hydrogen peroxide. Acid pre-treatment of silica prior to metal deposition led to bimetallic catalysts where the activity did not scale with the palladium content.
29
Schmidt, Jeremy T. "Stabilized hydrogen peroxide decomposition dynamics in one-dimensional columns". Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Spring2006/j%5Fschmidt%5F050306.pdf.
Testo completo
30
Rämö, J. (Jaakko). "Hydrogen peroxide- metals- chelating agents; interactions and analytical techniques". Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:9514269756.
Testo completoAbstract (sommario):
Abstract
Information about interactions among metals, hydrogen peroxide and chelating agents is needed to develop environmental technology and the operating efficiency of modern elemental chlorine free and total chlorine free bleaching processes. The work presented here focused on the properties of metal chelates and corrosion of titanium in an alkaline hydrogen peroxide solution. A comparative study between three rapid analysis methods, ICP-AES, XRF and ISE, was performed in pulp matrix and error sources of ISE were investigated in detail. Sensitive and selective GC methods for chelating agents ADA and NTA in water matrices were developed.
Decomposition of ADA (percentage of residual 71) was observed already at the hydrogen peroxide anion level of 400 mg/l in which DTPA was more persistent (percentage of residual 94). EDTA was stable even in the hydrogen peroxide anion level of 1200 mg/l, in which its percentage of residual was 94. DTPA, EDTA and ADA were more soluble in the presence of iron and manganese than in the absence of these metals. The chelation of iron appeared to be thermodynamically limited in hydrogen peroxide bleaching conditions.
Unalloyed (Grade 2) and alloyed (Grade 5) titanium corroded at the hydrogen peroxide anion level of 200 mg/l. The presence of calcium and silica inhibitors and further iron and manganese enhanced the critical hydrogen peroxide anion levels. Grade 5 was inferior to Grade 2. During rapid uniform corrosion, the potential of unalloyed titanium was under 200 mV (SHE) and lower than that of platinum.
Over 90% of manganese and many other metals could be leached into aqueous phase for ICP-AES analysis using chelation or acid hydrolysis. An XRF method for manganese, iron and copper in pulp including little or no sample treatment was developed. Measuring temperature differences and atmospheric carbon dioxide were observed to be notable error sources of the ISE technique.
31
Hayes, Lee. "The Spontaneous Generation of Hydrogen Peroxide from Amyloidogenic Peptides". Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485022.
Testo completoAbstract (sommario):
The characteristic deposition of usually soluble amyloidogenic proteins into insoluble fibrillar aggregates is the major pathological feature of the amyloidoses. These deposits can affect many different organs and .tissues throughout the body, giving rise to a whole range of individual amyloid diseases, including Alzheimer's disease, Parkinson's disease, type 2 diabetes and motor neurone disease. The mechanisms of amyloid cytotoxicity are still unclear but one potential mechanism which has recently gathered mounting evidence is the metal ion mediated formation of reactive oxygen species;·' in particular, hydrogen peroxide during their aggregation. The present study attempts to quantitatively examine the spontaneous generation of hydrogen peroxide .and correlate this formation to the stage of aggregation from a number of amyloidogenic peptides. involved in Alzheimer's disease, Parkinson's disease and type 2 diabetes. The role of metal ions in hydrogen peroxide generation and aggregation was also examined by the use of a range of metal ion chelators. A newly available assay which is highly sensitive for the detection of hydrogen peroxide, called Amplex Red, was used with these amyloidogenic peptides. Hydrogen peroxide was also detected indirectly from some of the peptides using electron spin resonance spectroscopy. In addition, fully aggregated forms of the amyloidogenic peptides were identified by the use of thioflavin T, a benzothiazole dye, and soluble multimeric forms of some of the peptides were detected by a specific immunoassay.The study confirms hydrogen peroxide is generated from these amyloidogenic peptides and that the generation of hydrogen peroxide occurs immediately after incubation and during the early stages of aggregatio~.This implies that spontaneous hydrogen peroxide formation could playa major role in the toxicity of these peptides and it may be possible that many, ifnot ·all, amyloidogenic peptides share such a common toxic mechanism. However, data involving the effect of metal . ion chelators show inhibitory effects on hydrogen peroxide generation but not on aggregation. The Amplex Red assay proved to be highly sensiti~~ and particularly rapid in its use for detecting hydr?gen peroxide and is therefore potentially useful as a method for high throughput screening for inhibitors of hydrogen peroxide formation from amyloidogenic peptides.
32
Kalu, Eric Egwu. "Simultaneous electrosynthesis of alkaline hydrogen peroxide and sodium chlorate". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28391.
Testo completoAbstract (sommario):
Simultaneous electrosynthesis of alkaline hydrogen peroxide and sodium chlorate in the same cell was investigated. The alkaline hydrogen peroxide was obtained by the electroreduction of oxygen in NaOH on a fixed carbon bed while the chlorate was obtained by the reaction of anodic electrogenerated hypochlorite and hypochlorous acid in an external reactor. An anion membrane, protected on the anode side with an asbestos diaphragm was used as the separator between the two chambers of the cell.
The effects of superficial current density (1.2 - 2.4 kA m⁻²), sodium hydroxide concentration (0.5 - 2.0 M) and catholyte flow (0.1 x 10⁻⁶ - 0.5 x 10⁻⁶ m³ s⁻¹) on the chlorate and peroxide current efficiencies were measured. The effect of peroxy to hydroxy mole ratio on the chlorate current efficiency was measured too.
The cell was operated at fixed anolyte flow of 2.0 x 10⁻⁶ m³ s⁻¹, inlet and outlet temperatures of 27/33°C (anode side), 20/29°C (cathode side), cell voltages of 3.0 - 4.2 V (current density of 1.2 - 2.4 kA -m⁻²) and a fixed temperature of 70°C in the anolyte tank. Depending on the conditions, alkaline peroxide solution and sodium chlorate were cogenerated at peroxide current efficiency between 20% and 86%, chlorate current efficiency between 51.0% and 80.6% and peroxide concentration ranging from 0.069 M to 0.80 M. The cogeneration of the two chemicals was carried out at both concentrated (2.4 - 2.8 M) and dilute (0 - 0.5 M) chlorate solutions. A relative improvement on the current efficiencies at concentrated chlorate was observed. A chloride balance indicated negligible chloride loss to the catholyte.
The results are interpreted in terms of the electrochemical and chemical kinetics and the hydrodynamics of the cell .Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
33
McAnoy, Andrew M. Sait Michelle Pantelidis Sue. "Establishment of a vaporous Hydrogen Peroxide bio-decontamination capability". Fishermans Bend, Victoria : Defence Science and Technology Organisation, 2007. http://hdl.handle.net/1947/8654.
Testo completo
34
Abejón, Elías Ricardo. "Ultrapurificación de peróxido de hidrógeno. Ultrapurification of hydrogen peroxide". Doctoral thesis, Universidad de Cantabria, 2013. http://hdl.handle.net/10803/112700.
Testo completoAbstract (sommario):
El descubrimiento y empleo de los semiconductores ha influido de forma decisiva en las profundas modificaciones que han vivido las sociedades avanzadas como consecuencia de la revolución tecnológica de la segunda mitad del siglo XX. De este modo se ha configurado la actual sociedad global, donde las tecnologías de la información y la comunicación se han constituido como el elemento característico e imprescindible del desarrollo científico y tecnológico en el que se basan las actuales formas de vida.
Las industrias que emplean materiales semiconductores o fabrican productos basados en los mismos demandan reactivos de calidad electrónica caracterizados por su limitado contenido en impurezas. Entre los reactivos de este tipo con mayor demanda se encuentra el peróxido de hidrógeno. Los procesos de ultrapurificación de peróxido de hidrógeno son necesarios para poder alcanzar los niveles de calidad exigidos por el sector, específicamente en lo referido a impurezas metálicas.
La revisión del estado del arte con respecto a las tecnologías disponibles para la ultrapurificación de peróxido de hidrógeno presenta diferentes alternativas que incluyen la destilación, la adsorción, el intercambio iónico y las tecnologías de membranas. El empleo de membranas de ósmosis inversa aparece como una opción prometedora desde el punto de vista del uso más sostenible de los recursos naturales (materiales, energía y agua).
En la presente Tesis Doctoral se ha estudiado el proceso de ultrapurificación de peróxido de hidrógeno mediante ósmosis inversa a escala de laboratorio. El peróxido de hidrógeno obtenido mediante un proceso de ósmosis inversa con membranas de poliamida cumple con los requisitos impuestos en el contenido de impurezas metálicas para ser considerado como SEMI Grado 1, el grado menos exigente de los contemplados dentro de la calidad electrónica.
El estudio experimental del proceso a escala de laboratorio permite ajustar el modelo de Kedem-Katchalsky para el transporte de solvente y solutos a través de membranas y es capaz de explicar de forma satisfactoria la evolución de los valores de flujo de permeado y los coeficientes de rechazo de los elementos metálicos en función de la presión aplicada al sistema, evaluando los parámetros que caracterizan al proceso de separación de impurezas lo que permite simular el comportamiento del mismo.
La degradación que las membranas de ósmosis inversa sufren en un ambiente tan agresivo como el peróxido de hidrógeno es un factor a tener en cuenta durante la investigación del proceso de ultrapurificación. Por ello, a la vista de los resultados experimentales que muestran una vida útil extremadamente corta para las membranas en esta aplicación y ante la imposibilidad de encontrar en bibliografía referencias previas para la descripción de la evolución con el tiempo del comportamiento de las membranas bajo degradación oxidativa, se propone un modelo logístico de carácter empírica que complemente el modelo de permeación con la descripción del comportamiento durante la evolución de la degradación de la membrana.
Los modelos obtenidos y los parámetros ajustados permiten simular y optimizar instalaciones para procesos de fabricación bajo la configuración de cascadas de membranas integradas en contracorriente para alcanzar las calidades de peróxido de hidrógeno ultrapuro desde el Grado SEMI 1 hasta el Grado SEMI 5. El modelo ha sido completado con un balance económico lo que permite utilizar los beneficios económicos como función objetivo en la optimización.
Finalmente se ha planteado la optimización del proceso para distintos objetivos en la ultrapurificación de peróxido de hidrógeno mediante cascadas de membranas de ósmosis inversa. Estos objetivos se han concretado en el número óptimo de etapas que la cascada de membranas debe incorporar para la producción de cada uno de los grados de calidad electrónica y los valores óptimos para las principales variables del proceso en cada caso, de modo que se maximice el beneficio económico del proceso; y en el estudio de la influencia de los precios unitarios de los principales recursos necesarios (materia prima, membranas y energía eléctrica) y de diferentes restricciones de mercado sobre la configuración óptima del proceso.The discovery and posterior use of semiconductor materials have greatly influenced the deep changes that developed societies have experienced as consequence of the technological revolution of the second half of the XX century. This way, the present global society has been configured, where the information and communication technology can be considered as the characteristic and indispensable cornerstone of the scientific and technological development which current life ways are based on. The semiconductor industrial sector requires electronic quality chemicals which can be characterized by their very limited impurity content. Among this type of chemicals, hydrogen peroxide can be found among the ones with highest demands. Hydrogen peroxide ultrapurification processes are necessary to attain the purity levels required by the sector, specifically for the metallic impurities concentrations. The bibliographical review about the state of the art with respect to available ultrapurificationt echnologies for hydrogen peroxide introduces different alternatives, including distillation, adsorption, ion exchange and membrane technologies. The use of reverse osmosis membranes appears as a promising option from the point of view that considers the most sustainable use of the natural resources (raw materials, energy and water). In this PhD Thesis, the hydrogen peroxide ultrapurification process by reverse osmosis has been investigated at lab-scale level. The hydrogen peroxide obtained by means of a reverse osmosis process with polyamide membranes fulfils with the requirements imposed about metallic impurities content to be considered as SEMI Grade 1 chemical, the least exigent grade of the electronic quality framework. The experimental study of the process at lab scale allows the fit to the Kedem-Katchalsky model for both solvent and solute transport through membranes and it is able to explain in a satisfactory way the evolution of the permeate flux and the rejection coefficients of the metallic elements as a function of the applied pressure by evaluating the parameters that characterize the impurities separation process and lets its performance simulation. The degradation of the reverse osmosis membranes in such a harsh medium as hydrogen peroxide is a factor to have under consideration during the investigation of the ultrapurification process. Hence, as a consequence of the analysis of the experimental results that evidence an extremely short effective lifetime for the membranes in this application and the lack of a previous bibliographic reference for the description of the time evolution of the membrane performance under oxidative degradation, an empirical logistic model was formulated to complement the permeation model with the description of the performance during the evolution of the membrane degradation The model that describes the lab-scale hydrogen peroxide permeation is useful to simulate and optimize industrial-scale installations for manufacturing purposes under the countercurrent integrated membrane cascade configuration to produce electronic quality hydrogen peroxide, from SEMI Grade 1 to SEMI Grade 5. The model has been completed with an economic balance which allows the use of the economic profit as an optimization target function. Lastly, the optimization with different targets as objectives of the hydrogen peroxide ultrapurification process by reverse osmosis membrane cascades has been performed. This objectives have been specified as the optimum number of stages that a membrane cascade should incorporate for the production of each electronic grade and the optimum values for the main process variables have been solved to maximize the economic profit of the process; and the study of the influence of the unitary prices of the principal required resources (raw material, membranes and electric energy) and different market restrictions over the optimal process configuration.
35
Mehta, Anjum. "MICROMACHINED ELECTROCHEMICAL SENSORS FOR HYDROGEN PEROXIDE AND CHLORINE DETECTION". Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3464.
Testo completoAbstract (sommario):
Hydrogen peroxide and chlorine detection is critical for many biological and environmental applications. Hydrogen peroxide plays important roles in a variety of fields including plant physiology, medical, environmental and biochemical applications. Its role in plant defense and signal transduction, diseases such as Parkinson's and Alzhemier's, industrial processes such as disinfection and wastewater treatment and biochemical enzymatic reactions is critical. Given the gamut of areas that hydrogen peroxide is a key component of; its detection assumes great importance. Similarly chlorine has long been used as a disinfectant for making drinking water safe, but excessive chlorination is an environmental and health hazard in itself. In this work, micromachining techniques have been used to design, fabricate and test electrochemical sensors and microneedle structure that can be integrated for detection of hydrogen peroxide and free chlorine. A novel nanomaterial has been integrated with the hydrogen peroxide microsensor, which greatly increases the sensor lifetime and robustness. Miniaturization, low detection limits, high sensitivity and selectivity, as well as ease of fabrication are some of the other advantages of this work.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
36
Smith, Samuel Lewis. "An EPR study of antibacterial systems containing hydrogen peroxide". Thesis, Cardiff University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422080.
Testo completo
37
Parsy, Christophe C. "Flavin and electron deficient ketones as hydrogen peroxide activators". Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343927.
Testo completo
38
Bannister, Jonathan. "Chemical degradation of PFAS using hydrogen peroxide and persulfate". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-82092.
Testo completoAbstract (sommario):
PFAS are a group of relatively newly discovered man-made pollutants. PFAS contains a C-F bond which is one of the strongest bonds in organic chemistry. Therefore, PFAS are not easily degradable and, once release into nature, are very persistent. PFAS are also labile in natural environments and therefore, they can sometimes be found far from the source of pollution. Their persistent and labile nature, in combination with their bioaccumulation ability and human health effects make of this compounds an important contaminant to take care of. Currently there are not stablish, wellfunctioning methods to treat contaminated soils and waters. A lot of research is performed at the moment to find good treatment options. In this work a test to chemically degraded spiked samples of PFOA, PFOS and PFBA was performed. By means of experimental design tools, we aim to evaluate which operational factors are relevant for this treatment. Best results when using hydrogen peroxide as a reactant was 70% degradation for PFOS and 42% degradation for PFOA. When persulfate was used as a reactant, a 57% degradation of PFOS, 99% degradation of PFOA and 99% degradation of PFBA was achieved.
39
PELLAVIO, GIORGIA. "Aquaporins permeability to hydrogen peroxide may control oxidative stress". Doctoral thesis, Università degli studi di Pavia, 2021. http://hdl.handle.net/11571/1448466.
Testo completoAbstract (sommario):
Transmembrane water channel proteins, known as aquaporins (AQPs), play a pivotal role in many biological processes including volume regulation, cell migration and proliferation, and adipocyte metabolism. Recently, it has been demonstrated the involvement of some AQPs, known as “peroxiporins”, in the transport of hydrogen peroxide (H2O2). H2O2 is the most abundant and stable reactive oxygen species (ROS) in living cells and H2O2 can have different effects depending on its concentration. Physiological levels of H2O2 induce positive adaptive responses acting as second messenger, while excessive levels provoke negative effects as apoptosis and cell death.
Since AQPs allow the diffusion of H2O2 across plasma membranes to the extracellular fluid, they have been considered as a possible ROS scavenging mechanism. Until now, AQP1, 3, 5, 8, 9 and 11 are the mammalian AQPs involved in H2O2 diffusion. This project aims to understand the mechanism of AQPs as peroxiporins in mediating H2O2 diffusion through cellular plasma membrane.
The guiding thread of this thesis was, on the one hand, the analysis of the role of peroxiporins in some pathophysiological conditions and, on the other, the identification and characterization of new gating modulators.
In particular this thesis aimed:
1. to investigate the negative role of human Papillomavirus (HPV) infection on the aquaporin-mediated hydrogen peroxide elimination which affects human sperm functioning;
2. to clarify AQPs/peroxiporins involvement in malignant pleural mesothelioma progression (MPM);
3. to identify and characterize new aquaporin modulators to counteract the oxidative stress.
As a whole, AQPs permeability alteration (and sensitivity to oxidative stress) in HPV infection and in MPM seems to reduce the fertility of sperm cells and make MPM cells resistant to conventional chemotherapy, respectively. The possibility to modify the gating of the AQPs and ROS scavenging opens to new therapeutic strategies for the treatment of debilitating diseases involving oxidative stress namely neurodegenerative diseases and cancer.
40
Melada, Stefano <1974>. "New catalysts for the direct synthesis of hydrogen peroxide". Doctoral thesis, Università Ca' Foscari Venezia, 2005. http://hdl.handle.net/10579/829.
Testo completo
41
BRANCO, ELOISA P. "Estudo comparativo da cor dental, in vivo, entre clareamentos sem aceleraçao, acelerado por LED e por laser, com análise dos resultados imediatos e a longo prazo". reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11699.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-10-09T12:54:53Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:07:04Z (GMT). No. of bitstreams: 1 12797.pdf: 513559 bytes, checksum: 4b6e71bdbea803b32a3222d0b42f7b13 (MD5)
Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia)
IPEN/D-MPLO
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo
42
Jana, Prabhas. "Environ-friendly production of hydrogen peroxide from direct catalytic liquid phase oxidation of hydrogen or hydrogen-containing compounds". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2007. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2571.
Testo completo
43
Goebel, James Robert. "A STUDY OF THE HYDROGEN BONDING CHARACTERISTICS OF HYDROGEN PEROXIDE BY MATRIX ISOLATION VIBRATIONAL SPECTROSCOPY". University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin971366564.
Testo completo
44
Zeng, Minyu. "The electrochemical approaches towards the distributed generation of hydrogen peroxide". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708680.
Testo completo
45
Wankasi, Mieebi Martin. "Studies on the reactions of respiratory haemproteins with hydrogen peroxide". Thesis, University of Essex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421139.
Testo completo
46
MacSween, Jeffrey Vanek. "Investigating the microwave-hydrogen peroxide treatment process for potential commercialization". Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55365.
Testo completoAbstract (sommario):
Two pilot-scale, dielectric heaters, that utilize different frequencies of electromagnetic radiation (EMR), were modified to treat organic slurries with the aid of hydrogen peroxide (H₂O₂). Organic slurries investigated include: waste activated sludge (WAS), liquid dairy manure (DM), and palm oil mill effluent (POME). Treatment efficacy was evaluated in terms of changes in the substrate’s digestibility, available nutrients, and physical properties. The first heating system operated at a microwave frequency of 915MHz (MW-H₂O₂) and was modified to attain treatment temperatures above 100°C. Results showed that such high temperatures permitted the effective use of larger oxidant dosages, which was found to be beneficial for treating DM and useful for treating WAS, in select circumstances. However, the additional equipment costs and difficulties encountered in operating a pressurized high temperature dialectic heating system may prove inhibiting at larger scales. The second heating system used radiofrequency EMR at 27MHz (RF-H₂O₂) and was modified from its original batch configuration for continuous operation. The continuous RF-H₂O₂ process, the first of its kind, was demonstrated to be a viable treatment technology that achieved comparable results to the better studied MW-H₂O₂ system for DM and WAS substrates. A controlled comparison of the two dielectric heaters showed that their treatment efficacy was similar, but suggested that heating at 27MHz offers advantages with respect to its operation and the degradation of organics. The effect of higher heating rates and a 60°C treatment regime on WAS were also investigated, revealing that the treatment efficacy of the MW/RF-H₂O₂ process was suppressed in both cases, particularly in regards to the release of nutrients. Using original experimental results and information from the literature, a full-scale, RF-H₂O₂ process is presented for treating thickened WAS from one million people. The proposed system recommends three 900kW 27MHz dielectric heaters, a final treatment temperature of 95°C, a H₂O₂ dosage of 0.35%(v/v) per percent of dry solids, a heat exchanger to preheat the substrate, and an optional holding tank to enhance the release of orthophosphates.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
47
Larisch, Belinda C. v. "Effect of DTPA and hydrogen peroxide on activated sludge performance". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0027/NQ38921.pdf.
Testo completo
48
Mahajan, Vishal Khomdeo. "Study of chalcopyrite oxidation in hydrogen peroxide-ethylene glycol system". abstract and full text PDF (free order & download UNR users only), 2005. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1433392.
Testo completo
49
Myers, James L. "The hydrogen peroxide and sulfur dioxide chemistry of Atlanta rainwater". Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/25874.
Testo completo
50
Murphy, Craig E. "Alkaline hydrogen peroxide bleaching : a study of the evolved gases". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38250.
Testo completoAbstract (sommario):
The principle objectives of this thesis are to determine which gases are evolved during alkaline hydrogen peroxide bleaching, and to develop techniques to measure these gases. Also, the relationship of the composition of the evolved gases from alkaline hydrogen peroxide bleaching of mechanical pulp to the reaction kinetics was elucidated. We have shown that the only gas being evolved into the bleaching headspace is oxygen; whereas, carbon dioxide is produced and fixed in solution as carbonate.A new non-invasive technique for measuring the amount of oxygen evolved throughout the bleaching reaction was developed. This technique is able to be used in laboratory bleaching experiments that simulated most industrial parameters except consistency, which is limited to hand mixing at medium (10--12%) consistencies. With this method, we have shown that pulp washing, caustic charge and addition of chelating agent play key roles in the rates of oxygen evolution due to the decomposition of hydrogen peroxide. Better washing and higher chelating agent additions result in significant lowering of the rates of oxygen evolution. The rate of decomposition has been related to the dissociation of hydrogen peroxide which is dependent on pH.
The effect of transition metal ions on the kinetics of hydrogen peroxide decomposition during alkaline hydrogen peroxide bleaching of mechanical pulps was investigated. Iron, whether added or native to the pulp, did not contribute to the decomposition of hydrogen peroxide in the presence of lignin. Manganese is the main catalyst for peroxide decomposition, whether added or native to the pulp. The initial rate of oxygen evolution, in the presence of manganese, varies linearly with manganese concentration. Although alkali itself does decompose hydrogen peroxide, increased caustic charge results in an increase in the manganese induced decomposition rate. Kinetic equations are presented, which account for manganese concentration and caustic charge. The effect of DTPA on reducing the rate of hydrogen peroxide decomposition has been attributed to the chelation of manganese.
The relationship between hydrogen peroxide decomposition and the oxidation state of iron and manganese was determined visually. The effect of other bleaching additives on the catalyzed decomposition of hydrogen peroxide were also evaluated. Manganese is unreactive in the +II state, yet very reactive in the +III and +IV forms. Iron is not reactive in the presence of lignin. The presence of cellulose acts to prevent the formation of large low surface area precipitates of manganese III and IV. Manganese IV is the most likely reactive species in alkaline hydrogen peroxide bleaching. DTPA will bind Mn(II) but not the other oxidation states. The DTPA-manganese complex once formed is stable even after the pH is increased.
A new technique for the determination of carbon dioxide produced during hydrogen peroxide bleaching is presented. Carbon dioxide is produced during alkaline hydrogen peroxide bleaching, from reactions of hydrogen peroxide and lignin. The rate of carbon dioxide evolution varies linearly with lignin concentration. Kinetic equations are presented and rate constants have been calculated. The source of carbon dioxide is most likely decarboxylation of carboxylic acid groups formed in lignin by alkaline hydrogen peroxide oxidation.