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<p>Usled visoke fotokatalitičke efikasnosti u procesima preči&scaron;ćavanja voda i vazduha, titan(IV)-oksid (TiO₂) se u poslednje vreme sve vi&scaron;e ispituje u oblasti za&scaron;titi životne okoline. Međutim usled visokih zahteva koje fotokatalizatori u ovoj oblasti treba da zadovolje, kao &scaron;to su aktivnost, selektivnost, netoksičnost, ekonomičnost i stabilnost, potreba za razvojem fotokatalizatora sa povoljnijim karakteristikama se sve vi&scaron;e nameće kao prioritet za buduća istraživanja. Inovativni pristup ove doktorske disertacije je usmeren upravo ka razvoju novih kompleksnih sistema na bazi oksida titana i slojevitih hidroksida, osvrćući se na postavljenu polaznu hipotezu o mogućem sinergetskom efektu komponenata u dostizanju visoke fotokatalitičke efikasnosti, kao i u pobolj&scaron;anju njihovih op&scaron;tih katalitičkih performansi. ZnAl i NiAl slojeviti hidroksidi su izabrani kao nosači aktivne komponente (TiO₂). Modifikacija postojećih metoda sinteze je izvr&scaron;ena kako bi se pospe&scaron;ila interakcija aktivne komponente i nosača. Komparativna istraživanja novonastalih materijala pripremljenih primenom četiri nove metode sinteze pokazala su da se izborom metodologije sinteze i prirode interakcije između aktivne faze TiO₂ i aktivnog nosača mogu pobolj&scaron;ati fotokatalitičke performanse kompozitnih materijala u odnosu na referentne vrednosti dobijene za ZnAl slojevite hidrokside. Iako je udeo TiO₂ veoma mali u novonastalim kompleksnim sistemima, fotokatalitička efikasnost razgradnje model polutanta je zadovoljavajuća, usled pobolj&scaron;ane dostupnosti aktivnih centara i usled limitiranja aglomeracije TiO₂. Potvrđeno je da metoda i uslovi sinteze bitno utiču na strukturu, teksturu i povr&scaron;inske karakteristike formiranih kompozita, uz rezultujuće značajne razlike i u fotokatalitičkim svojstvima sintetisanih materijala. Komparativna ispitivanja fotokatalitičke efikasnosti uz primenu odabranih test reakcija (razgradnje metilenskog plavog, rodamina B i metil oranža) pokazala su da uzorci sintetisani metodom impregnacije u baznoj sredini pokazuju najbolje fotokatalitičke performanse u &scaron;irem spektru zračenja, &scaron;to je pripisano formiranju faza ZnO i ZnTiO₄ u ovim uslovima, detektovanih XRD, FTIR i XPS analizama. Takođe, mikrobiolo&scaron;ke analize na antimikrobno dejstvo su pokazale da, iako TiO₂ ne pokazuje inhibitoran efekat, uzorci sintetisani impregnacijom u baznoj sredini imaju i najizraženiji inhibitorni efekat na rast gram-pozitivnih i gram-negativnih bakterija, &scaron;to dodatno ukazuje na doprinos sinergetskog efekta slojevitih oksida i aktivne faze me&scaron;ovitih oksida u formiranju aktivnih centara visoke fotokatalitičke aktivnosti. Uzorci dobijeni primenom metoda koprecipitacije pokazuju nižu, ali zadovoljavajuću fotokatalitičku aktivnost, dok uzorci sintetisani metodom impregnacije u neutralnoj sredini pokazuju najnižu fotokatalitičku aktivnost i mali inhibitorni efekat.<br />Istraživanja u ovoj doktorskoj disertaciji dala su doprinos novim saznanjima o karakteristikama kompozitnih materijala tipa TiO₂/ZnAl slojeviti hidroksidi bitnim za obezbeđenje fotokatalitičke aktivnosti materijala ovog tipa u &scaron;irem spektru zračenja (UV/VIS), kao i ukupnih performansi koje omogućuju njihovu primenu u različitim ekolo&scaron;kim procesima (preči&scaron;ćavanje vode i vazduha od organskih, neorganskih i biolo&scaron;kih polutanata).</p> / <p>Recently, titanium-dioxide (TiO₂) has been extensively researched in the field of environmental protection due to its high photocatalytic efficiency in processes for water and air purification. Considering the high demands that are constantly set for photocatalysts in this field of research, such as activity, selectivity, stability, cost-effective and non-toxic, the need to develop photocatalysts with better characteristics is becoming increasingly evident as a priority for future research. The novel approach of this Ph.D. thesis is oriented towards the development of new complex systems on the basis of titanium-dioxide and layered double hydroxides, taking into account the hypothesis about their possible synergetic effect achieving high photocatalytic efficiency and obtaining better overall catalytic performances. ZnAl and NiAl layered double hydroxides have been chosen as the catalyst support of the active component (TiO₂). In order to initiate the interaction between the active component and support, current synthesis methods have been modified. The novel materials were synthesized using four new different synthesis methods. Comparative investigation showed that the synthesis method, as well as the nature of the interaction between the active phase and the support can improve the overall photocatalytic performances of the composite materials when compared to the referent values obtained from ZnAl layered double hydroxides. Although the TiO₂ amount is low in the novel complex systems, photocatalytic efficiency for the degradation of model pollutants is satisfactory due to improved accessibility to the active centres, as well as due to limitation of TiO₂ agglomeration. It was confirmed that the synthesis method and conditions considerably affect the structural, textural and surface characteristics of the formed composites, resulting in significant differences in photocatalytic characteristics of the synthesized materials. Comparative research of photocatalytic efficiency in the chosen test reactions (methylene blue, rhodamine B, and methyl orange degradation) showed that the samples synthesized by the wet impregnation method in alkaline solution exhibited the best photocatalytic performance in the wide range of radiation that attributed to the formation of ZnO phase and ZnTiO₄ detected by XRD, FTIR and XPS analysis. Also, the research on the antimicrobial activity showed that, although TiO₂ has no inhibitory effect, the samples synthesized by the wet impregnation method in alkaline solution have the highest inhibitory effect on the&nbsp;growth of gram-positive and gram-negative bacteria, confirming the contribution of the synergic effect to the formation of active centres with high photocatalytic activity. The samples obtained by the coprecipitation method had lower, but satisfactory photocatalytic activity, while samples synthesized by the wet impregnation method in water solution showed the lowest photocatalytic activity, as well as low inhibitory effect on the bacteria growth. The research in this Ph.D. thesis contributed to the knowledge on the characteristics of novel composite materials TiO₂/ZnAl layered hydroxides that are of essential importance concerning their photocatalytic activity in the wide range of radiation (UV / VIS), as well as their overall performance that enable their use in a variety of ecological processes, such purification of water and air pollution from organic, inorganic and biological pollutants.</p>

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Made available in DSpace on 2014-10-09T12:27:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:48Z (GMT). No. of bitstreams: 0 / Complexos contendo íons de terras raras são de grande interesse na fabricação de dispositivos eletroluminescentes como é o caso do diodo emissor de luz construído com compostos orgânicos (OLED). Esses dispositivos, utilizando íons de terras raras trivalentes (TR3+) como centros emissores, exibem alta luminescência com bandas espectrais extremamente finas devido à estrutura dos seus níveis de energia, tempos de vida longos e a alta eficiência quântica. Este trabalho relata a preparação de complexos de &beta;-dicetonatos (tta - tenoiltrifluoroacetonato e acac - acetilacetonato) de terras raras (Tb3+, Eu3+ e Gd3+) contendo ligante macrocíclico éter coroa (DB18C6 - dibenzo18coroa6) e de filmes poliméricos de UO22+. Os materiais obtidos foram caracterizados por titulação complexométrica com EDTA, análise elementar de CH, espectroscopia de absorção na região do infravermelho, análise termogravimétrica, difratometria de raios X (método do pó) e espectroscopia de luminescência. Na manufatura do dispositivo OLED construído neste trabalho utilizou-se a técnica de deposição física de filmes finos por fase vapor (PVD, Physical Vapor Deposition). / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:54Z (GMT). No. of bitstreams: 0 / A solução sólida céria-samária é uma das principais candidatas para aplicação como eletrólito sólido em células a combustível de óxido sólido, devido sua alta condutividade iônica em temperaturas intermediárias (500-750 ºC) de operação. Um dos problemas ainda não solucionados com relação a este material é sua relativamente baixa sinterabilidade. Nesse trabalho foi utilizado o método de sinterização em duas etapas visando melhorar a densificação com reduzido tamanho médio de grãos. Soluções sólidas comercial e obtida por mistura de óxidos de composição Ce0,8Sm0,2O1,9 foram utilizadas. Para fins comparativos também foi utilizado o método denominado sinterização em duas etapas tradicional que visa a obtenção de amostras densas independentemente do tamanho médio de grãos. Resultados de densidade aparente e retração linear revelaram que ambos os tipos de amostras têm comportamento distinto. Para a solução sólida comercial, a retração total até 1400 ºC foi de ~18%. Só foram obtidos resultados de densidade significativos ao utilizar temperaturas elevadas (igual ou superior a 1300 ºC). Para o material obtido por mistura de óxidos não foi possível atingir densidades maiores que 90% da densidade teórica. A sinterização em duas etapas tradicional produziu amostras densas, da mesma forma, que a não-tradicional, mas com tamanhos de grãos consideravelmente maiores. Amostras sinterizadas por ambos os processos foram analisadas por espectroscopia de impedância para a determinação da condutividade elétrica em função da temperatura, e não apresentaram variação significativa nas condutividades intra e intergranular. A sinterização em duas etapas não resultou em melhorias na densificação e nem na condutividade elétrica das amostras. Entretanto, a redução obtida no tamanho médio de grãos pode melhorar as propriedades mecânicas. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

The master’s thesis deals with the environmental aspects of combined heat and power station Červený Mlýn (Red Mill). The introductory part of the thesis focuses on the current production technology and the electricity balance of the power station. The heat and power station (also called combined cycle heat and power plant) is scrutinized in terms of emissions sources, focusing on pollutant emissions to air in the following chapter. In this part of the thesis the quantities of the released emissions, namely solid particulate matter (TZL), sulfur dioxide (SO2), carbon dioxide (CO2) are also calculated. The calculation is worked out according to the valid Czech legislation. Further on, the current production technology of the power station is compared with the best available technologies according to the valid directive 2008/1/EC of the European Parliament and of the Council concerning integrated pollution prevention and control. The last chapter presents the innovative technologies which could possibly be installed to reduce pollution emissions (especially nitrogen oxides - NOx) to air at the heat and power station Červený Mlýn.