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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vyhořívání organických lehčiv v cihlářském střepu / The Combustion of Organic Lightweighting Agent in Brick Body

Kašíková, Milada January 2017 (has links)
This diploma thesis deals with the burnout of organic substances in the brick body using different types of lightener for different types of soils. The theoretical part summarizes the different ways of lightening and a descri-ption of burnable organic substances. The practical part contains the results of various experiments and individual graphs with the course of temperature increase during firing using various burnable substances.
2

Panevėžio miesto įtakos Nevėžio upės vandens kokybei ir prevencinių priemonių ekologinei situacijai gerinti įvertinimas / The estimation of impact of Panevėžys city on river Nevėžis water and preventive tools for the improvement of ecological situation

Koriapina, Natalija 14 June 2006 (has links)
This research deals with Panevėžys city on the river Nevėžis water quality from 1994 to 2004 years. There was collect and work up the information. There was determined the water pollution of biogenical (nitrites, nitrates, phosphates) substances and of the organic substances (biochemical usage of oxygen and chemical usage of oxygen). After the statistical calculation there was determined and presented the analysis of statistical data. There was estimated preventive tools for the improvement of ecological situation. According to estimations of pollution by industrial and domestic sewage of Panevėžys on the water quality of Nevėžis river there were presented conclusions and suggestions.
3

Odstranění dusičnanů ze zemědělských smyvů / Nitrate removal from agricultural runoff

Schrimpelová, Kateřina January 2020 (has links)
The increasing concentration of nitrates in surface water and groundwater is becoming a global problem. The dissertation thesis is focused on the denitrifying bioreactors with organic fill material designed for the reduction of nitrate input from agricultural areas in the Czech Republic. A set of laboratory experiments was performed – static leaching tests and column tests, including chemical analyses of outflow water and ecotoxicological bioassays. Seven materials common in the Czech Republic, various process parameters, types and lengths of bioreactor shutdown in dry periods and the use of outflow water for irrigation were tested. The thesis deals with both denitrification efficiency and ways of reducing negative effects. An evaluation of the overall effect bioreactors is included along with a prediction regarding leaching over the following years.
4

Využití hybridně stabilizovaného oblouku pro zplyňování biomasy a degradaci ve vodě rozpustných organických látek / Hybridly stabilized arc as a tool for biomass gasification and the degradation of water-soluble organic compounds

Hlína, Michal January 2018 (has links)
(EN) A plasma torch (the source of plasma) with Gerdien arc was utilized as the source of energy in a reactor for gasification of biomass and for the degradation of organic compounds dissolved in water circling around the arc where the dissolved compounds are exposed to an intensive ultraviolet radiation. Thermal plasmas have electrons, ions and neutrals in thermal equilibrium and are quite often characterized by higher pressures and temperatures than nonthermal plasmas. Therefore, thermal plasmas generally carry a huge amount of energy which can be employed for heating and subsequent gasification of various types of materials. Thermal plasma gasification reactors are operated at higher temperatures than conventional reactors which results in a very good composition with a high percentage of hydrogen and carbon monoxide in produced synthetic gas. Spruce sawdust and spruce pellets were gasified at feeding rates up to 60 kg/h. Oxidizing media such as water, carbon dioxide, oxygen or their mixtures had to be added to the reactor during experiments to avoid the formation of solid carbon. The compositions of produced gas significantly corresponded to calculated compositions and the produced gas was of high quality - hydrogen content approximately 45 % vol., carbon monoxide approximately 48 % vol., a...
5

Stav chemických parametrů stojatých a tekoucích povrchových vod vybrané části Velké podkrušnohorské výsypky na Sokolovsku / Status of standing and flowing surface waters chemical parameters of the selected part of the Podkrušnohorská dump in the Sokolov

KORANDOVÁ, Martina January 2013 (has links)
This diploma thesis deals with the description of the chemistry of stagnant and flowing surface waters in selected part of the Velká podkrušnohorská dump and subsequent statistical processing of data. Sulfates are dominating element of the stagnant and flowing water, which form sulfato complexes with elements Ca2 + and Mg2+. The values CHSKCr in stagnat water are half compared to flowing water (upper and lower reaches). Higher values CHSKCr are result of biochemical, chemical and biological processes in the aquatic environment in stagnant water.
6

Processos de tratamento não convencionais para degradação do antibiótico sulfadiazina em meio aquoso. / Non-conventional treatment processes for the degradation of the antibiotic sulfadiazine in aqueous medium.

Acosta, Arlen Mabel Lastre 25 April 2016 (has links)
A presença de antibióticos no meio ambiente aquático tem causado crescente preocupação mundial. Além dos relatos de resistência de bactérias a antibióticos, essa classe de fármacos também pode causar efeitos tóxicos e atuar como perturbadores endócrinos em diversos organismos vivos e, possivelmente, em humanos. Dentre os antibióticos comumente usados destacam-se as sulfonamidas, detectadas em águas subterrâneas e superficiais. Os processos avançados de oxidação (POA) têm sido apontados como tecnologias eficientes para tratamento de poluentes recalcitrantes em diferentes matrizes aquosas. Dentre os POA, o processo foto-Fenton é uma alternativa para a degradação de compostos não biodegradáveis, incluindo fármacos. Uma vez que a principal limitação do processo é o intervalo de pH (2,5- 4,0), a reação pode ser vantajosamente conduzida empregando-se substâncias bio-orgânicas solúveis (BOS) como agentes complexantes de Fe3+ em condições ligeiramente ácidas (pH 5). Por sua vez, o emprego da energia ultrassônica tem sido menos estudado. Nesse contexto, o objetivo deste trabalho é estudar a degradação do antibiótico sulfadiazina (SDZ) por meio do processo foto-Fenton na presença de substâncias bio-orgânicas solúveis (UVvis/ Fe3+/H2O2/BOS) e do processo de cavitação por meio de ultrassom (US). Os resultados obtidos mostram que a sulfadiazina é eficientemente degradada por ultrassom de alta frequência. As maiores porcentagens e taxas de remoção são obtidas usando menor frequência de operação (580 kHz), maior potência dissipada e em pH ligeiramente ácido (melhor condição: pH 5,5). Além disso, a reação de Fenton, combinada com o tratamento US, melhorou notavelmente a degradação da SDZ, particularmente quando quantidades extras de H2O2 foram adicionadas ao sistema. Por sua vez, o uso de BOS como aditivos no processo foto-Fenton apresenta influência marcante na fotodegradação da SDZ em condições ligeiramente ácidas (pH 5). Os BOS podem estabilizar espécies de ferro em solução aquosa em pH próximos ao neutro, o que constitui uma propriedade de grande interesse. Sob as condições estudadas, o BOS CVT230 foi mais eficiente do que FORSUD, provavelmente devido às diferenças nos grupos funcionais presentes na composição destas substâncias. Finalmente, foram calculados os indicadores de consumo de energia elétrica por ordem de grandeza (EEO) para o processo de ultrassom (1572 kW h m-3 ordem-1) e área do coletor por ordem de grandeza (ACO) para o processo foto-Fenton (8,07 m2 m-3 ordem-1). / The potential impacts of antibiotic residues in the environment have become an emerging concern during recent years due to their relation with the development of resistant bacteria, and in some cases to their ability to cause toxic and endocrine disrupting effects in humans and other living organisms. Highlighted among the commonly used antibiotics are the sulfonamides, detected in groundwater and surface water. Advanced oxidation processes (AOP) might constitute an important alternative to deal with pharmaceuticals degradation. Among them, the photo-Fenton process has been widely used. One of its major drawbacks is the highly acidic pH needed (2,5-4,0) to avoid the formation of photochemically inactive iron oxides and hydroxides. The ability of soluble bio-organic substances (SBO) to complex metal cations such as iron is useful for the development of photo-Fenton at mild acidic conditions (pH 5). In turn, the use of ultrasonic energy has been less studied. In this context, the aim of this work is to study the degradation of the antibiotic sulfadiazine (SDZ) by the photo-Fenton process in the presence of soluble bio-organic substances (UV-vis/Fe3+/H2O2/SBO) and by ultrasonic cavitation (US). The results confirm that SDZ is effectively degraded by highfrequency ultrasound. Higher SDZ percent removals and removal rates were observed for the lowest operating frequency (580 kHz), higher dissipated power, and in slightly acidic solution (pH 5.5). On the other hand, SDZ degradation is highly improved in the case of the US/ Fe(II)/H2O2 system. The use of the SBO as Fenton additives in turn has a remarkable influence in SDZ photodegradation at slightly acid conditions (pH 5). This could be ascertained to the complexation of iron by the SBO, hence maintained in the reaction medium as a photoactive species. Under the studied conditions, the BOS CVT230 was more efficient than FORSUD, probably due to differences in the functional groups present in the composition of these substances. Finally, the figures-of merit electrical energy per order (EEO) and collector area per order (ACO) were calculated for the ultrasound (1572 kW h m-3 ordem-1) and photo-Fenton (8,07 m2 m-3 ordem-1) processes respectively.
7

Processos de tratamento não convencionais para degradação do antibiótico sulfadiazina em meio aquoso. / Non-conventional treatment processes for the degradation of the antibiotic sulfadiazine in aqueous medium.

Arlen Mabel Lastre Acosta 25 April 2016 (has links)
A presença de antibióticos no meio ambiente aquático tem causado crescente preocupação mundial. Além dos relatos de resistência de bactérias a antibióticos, essa classe de fármacos também pode causar efeitos tóxicos e atuar como perturbadores endócrinos em diversos organismos vivos e, possivelmente, em humanos. Dentre os antibióticos comumente usados destacam-se as sulfonamidas, detectadas em águas subterrâneas e superficiais. Os processos avançados de oxidação (POA) têm sido apontados como tecnologias eficientes para tratamento de poluentes recalcitrantes em diferentes matrizes aquosas. Dentre os POA, o processo foto-Fenton é uma alternativa para a degradação de compostos não biodegradáveis, incluindo fármacos. Uma vez que a principal limitação do processo é o intervalo de pH (2,5- 4,0), a reação pode ser vantajosamente conduzida empregando-se substâncias bio-orgânicas solúveis (BOS) como agentes complexantes de Fe3+ em condições ligeiramente ácidas (pH 5). Por sua vez, o emprego da energia ultrassônica tem sido menos estudado. Nesse contexto, o objetivo deste trabalho é estudar a degradação do antibiótico sulfadiazina (SDZ) por meio do processo foto-Fenton na presença de substâncias bio-orgânicas solúveis (UVvis/ Fe3+/H2O2/BOS) e do processo de cavitação por meio de ultrassom (US). Os resultados obtidos mostram que a sulfadiazina é eficientemente degradada por ultrassom de alta frequência. As maiores porcentagens e taxas de remoção são obtidas usando menor frequência de operação (580 kHz), maior potência dissipada e em pH ligeiramente ácido (melhor condição: pH 5,5). Além disso, a reação de Fenton, combinada com o tratamento US, melhorou notavelmente a degradação da SDZ, particularmente quando quantidades extras de H2O2 foram adicionadas ao sistema. Por sua vez, o uso de BOS como aditivos no processo foto-Fenton apresenta influência marcante na fotodegradação da SDZ em condições ligeiramente ácidas (pH 5). Os BOS podem estabilizar espécies de ferro em solução aquosa em pH próximos ao neutro, o que constitui uma propriedade de grande interesse. Sob as condições estudadas, o BOS CVT230 foi mais eficiente do que FORSUD, provavelmente devido às diferenças nos grupos funcionais presentes na composição destas substâncias. Finalmente, foram calculados os indicadores de consumo de energia elétrica por ordem de grandeza (EEO) para o processo de ultrassom (1572 kW h m-3 ordem-1) e área do coletor por ordem de grandeza (ACO) para o processo foto-Fenton (8,07 m2 m-3 ordem-1). / The potential impacts of antibiotic residues in the environment have become an emerging concern during recent years due to their relation with the development of resistant bacteria, and in some cases to their ability to cause toxic and endocrine disrupting effects in humans and other living organisms. Highlighted among the commonly used antibiotics are the sulfonamides, detected in groundwater and surface water. Advanced oxidation processes (AOP) might constitute an important alternative to deal with pharmaceuticals degradation. Among them, the photo-Fenton process has been widely used. One of its major drawbacks is the highly acidic pH needed (2,5-4,0) to avoid the formation of photochemically inactive iron oxides and hydroxides. The ability of soluble bio-organic substances (SBO) to complex metal cations such as iron is useful for the development of photo-Fenton at mild acidic conditions (pH 5). In turn, the use of ultrasonic energy has been less studied. In this context, the aim of this work is to study the degradation of the antibiotic sulfadiazine (SDZ) by the photo-Fenton process in the presence of soluble bio-organic substances (UV-vis/Fe3+/H2O2/SBO) and by ultrasonic cavitation (US). The results confirm that SDZ is effectively degraded by highfrequency ultrasound. Higher SDZ percent removals and removal rates were observed for the lowest operating frequency (580 kHz), higher dissipated power, and in slightly acidic solution (pH 5.5). On the other hand, SDZ degradation is highly improved in the case of the US/ Fe(II)/H2O2 system. The use of the SBO as Fenton additives in turn has a remarkable influence in SDZ photodegradation at slightly acid conditions (pH 5). This could be ascertained to the complexation of iron by the SBO, hence maintained in the reaction medium as a photoactive species. Under the studied conditions, the BOS CVT230 was more efficient than FORSUD, probably due to differences in the functional groups present in the composition of these substances. Finally, the figures-of merit electrical energy per order (EEO) and collector area per order (ACO) were calculated for the ultrasound (1572 kW h m-3 ordem-1) and photo-Fenton (8,07 m2 m-3 ordem-1) processes respectively.
8

Změny geochemismu povrchových vod ve vybraných povodích Krušných hor / Changes of geochemistry of surface water in selected catchments of the Ore Mountains

Navrátilová, Denisa January 2020 (has links)
This master thesis focuses on an analysis of surface water chemistry, long-term trends and the impact of drought on changes in concentrations of selected parameters in the upper Svatava, Rolava and Načetínský potok basins located in the Ore Mountains. Research on water quality in mountain spring areas is important, the consequences of various changes can be easily observed there. This work analyses the changes in surface water chemistry and discusses their possible causes, especially the impact of peat bogs and dry episodes. The parameters of water temperature, conductivity, pH, BOD5, COD, TOC, concentration of nitrate nitrogen, total phosphorus, phosphates, sodium, potassium, calcium and iron were investigated for the period 1993-2018. The available data are analysed using evaluation methods according to ČSN 75 7221 as well as box plots, Pearson correlation coefficient, PCA analysis and Mann-Kendall test. The greatest anthropogenic influence exhibited in Svatava, almost all concentrations reached their highest values there. In the Rolava and Načetínský potok basins, the influence of peatlands manifested itself by increasing the concentrations of iron, TOC and COD. The results of trends showed an increase both in pH and in surface water temperature related to an increase in air temperature, on the...
9

Aufwertung organischer Verbindungen durch Kopplung von Elektrooxidation und Wasserstoffentwicklung

Chen, Guangbo, Li, Xiaodong, Feng, Xinliang 01 February 2024 (has links)
Die elektrokatalytische Wasserspaltung gilt als die nachhaltigste und sauberste Technologie zur Produktion von H2. Leider wird die Effizienz durch die träge Kinetik der Sauerstoffentwicklungsreaktion (OER) an der Anode stark eingeschränkt. Im Gegensatz zur OER ist die Elektrooxidation organischer Stoffe (EOO) thermodynamisch und kinetisch günstiger. Daher hat sich die Kopplung der EOO mit der Wasserstoffentwicklungsreaktion (HER) als Alternative herauskristallisiert, weil dabei die katalytische Effizienz für die H2-Produktion erheblich verbessert werden kann. Gleichzeitig können hochwertige organische Verbindungen an der Anode durch Verbesserung der Elektrooxidation erzeugt werden. In diesem Kurzaufsatz werden die aktuellsten Fortschritte und Meilensteine, die bereits bei der Kopplung der EOO mit der HER erzielt wurden, vorgestellt. Der Fokus liegt auf dem Design des Anodenkatalysators, dem Verständnis des Reaktionsmechanismus und der Konstruktion des Elektrolyseurs. Darüber hinaus werden Herausforderungen und Perspektiven in Bezug auf die künftige Entwicklung dieser innovativen Technologie aufgezeigt.

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