Made available in DSpace on 2014-12-17T14:07:15Z (GMT). No. of bitstreams: 1 MaraTST_DISSERT.pdf: 2071273 bytes, checksum: 9636b6602dd1a469f78b17d077ba757f (MD5) Previous issue date: 2013-03-04 / In recent decades have seen a sharp growth in the study area of nanoscience and nanotechnology and is included in this area, the study of nanocomposites with self-cleaning properties. Since titanium dioxide (TiO2) has high photocatalytic activity and also antimicrobial, self-cleaning surfaces in your application has been explored. In this study a comparison was made between two synthesis routes to obtain TiO2 nanoparticles by hydrothermal method assisted by microwave. And after analysis of XRD and SEM was considered the best material for use in nanocomposites. It was deposited nanocomposite film of poly (dimethyl siloxane) (PDMS) with 0.5, 1, 1.5 and 2% by weight of nanoparticles of titanium dioxide (TiO2) by the spraying method. The nanocomposite was diluted with hexane and the suspension was deposited onto glass substrate, followed by curing in an oven with forced air circulation. The photocatalytic activity of the nanocomposite impregnated with methylene blue was evaluated by UV- vis spectroscopy from the intensity variation of absorption main peak at 660nm with time of exposure to the UV chamber. Changes in the contact angle and microhardness were analyzed before and after UV aging test. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by spectrophotometry Fourier transform infrared (FTIR).The results indicated that the addition of TiO2 nanoparticles in the coating PDMS gave high photocatalytic activity in the decomposition of methylene blue, an important characteristic for the development of self-cleaning coatings / Nas ?ltimas d?cadas tem-se observado um crescimento acentuado no estudo da ?rea de nanoci?ncia e nanotecnologia em que inclui-se nessa ?rea, o estudo de nanocomp?sitos com propriedades autolimpantes. Desde que o di?xido de tit?nio (TiO2) apresenta alta atividade fotocatal?tica e tamb?m, atividade antimicrobiana, sua aplica??o em superf?cies autolimpantes tem sido amplamente explorada. Neste trabalho foi feito uma compara??o entre duas rotas de s?ntese para obten??o de nanopart?culas de TiO2 pelo m?todo hidrot?rmico assistido por micro-ondas. Ap?s an?lise de DRX e MEV foi analisado o melhor material para aplica??o em nanocomp?sitos. Foram depositados filmes de nanocomp?sito de poli(dimetil siloxano) (PDMS) com 0,5, 1, 1,5 e 2% em massa de nanopart?culas de di?xido de tit?nio (TiO2) pelo m?todo de aspers?o. O nanocomp?sito foi dilu?do em hexano e a suspens?o foi depositada sobre l?minas de vidro, seguida de cura em estufa com circula??o for?ada de ar. A atividade fotocatal?tica do nanocomp?sito impregnado com azul de metileno foi avaliada pela t?cnica de espectroscopia de UV-V?sivel, a partir da varia??o da intensidade de absor??o do pico principal a 660 nm com o tempo de exposi??o em c?mara UV. Altera??es no ?ngulo de contato e na microdureza foram analisadas antes e ap?s o ensaio de envelhecimento UV. O efeito da radia??o ultravioleta na estrutura qu?mica da matriz de PDMS foi avaliado por espectrofotometria no infravermelho por transformada de Fourier (FTIR). Os resultados indicaram que a adi??o das nanopart?culas de TiO2 em PDMS conferiram ao revestimento boa atividade fotocatal?tica na decomposi??o do azul de metileno, caracter?stica importante para o desenvolvimento de revestimentos autolimpantes

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-10-11T20:39:41Z No. of bitstreams: 1 LaureniaMartinsPereiraGarcia_TESE.pdf: 2883896 bytes, checksum: f18e0865bcb2cb5e8b2dd2a291c24ebf (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-10-13T23:54:22Z (GMT) No. of bitstreams: 1 LaureniaMartinsPereiraGarcia_TESE.pdf: 2883896 bytes, checksum: f18e0865bcb2cb5e8b2dd2a291c24ebf (MD5) / Made available in DSpace on 2016-10-13T23:54:22Z (GMT). No. of bitstreams: 1 LaureniaMartinsPereiraGarcia_TESE.pdf: 2883896 bytes, checksum: f18e0865bcb2cb5e8b2dd2a291c24ebf (MD5) Previous issue date: 2016-05-05 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Nas ?ltimas d?cadas tem se observado um enorme interesse no estudo de materiais cer?micos nanoestruturados com propriedades fotocatal?ticas e fotoluminescentes. Um dos precursores ? o di?xido de tit?nio (TiO2) que possui propriedades ?pticas, por?m apresenta alto valor de band gap (3.2 eV), combinando-o com outros ?xidos como o ?xido de ?ndio (In2O3) intensificar? suas propriedades, j? que o In2O3 possui menor band gap (2,8 eV), al?m de apresentar absor??o no vis?vel sendo eficaz para aumentar a absor??o do TiO2. Neste trabalho o m?todo de spin-coating foi utilizado na deposi??o de filmes finos multicamadas de TiO2/In2O3. Na prepara??o dos filmes, foram utilizadas resinas obtidas pelo m?todo de polimeriza??o de complexos (MCP), as quais tiveram sua viscosidade ajustada em 20cps. As resinas foram depositadas sobre o substrato de sil?cio (Si) variando em 4, 8 e 16 camadas, logo ap?s, foram cristalizadas em diferentes temperaturas 300?C, 500?C e 700?C. A caracteriza??o dos filmes foi feita por meio de difra??o de Raios-X (DRX), microscopia eletr?nica de varredura com emiss?o de campo (MEV-FEG), microscopia de for?a at?mica (AFM), espectroscopia na regi?o do UV-V?sivel (UV-Vis) e medidas de fotoluminesc?ncia (FL). Os resultados de difra??o de Raios-X confirmaram a forma??o do TiO2 com fase anatase e do In2O3, n?o havendo intera??o qu?mica entre os ?xidos dos filmes. As imagens obtidas por microscopia de for?a at?mica mostraram filmes bem densificados com tamanho m?dio de gr?o variando de 15 a 35 nm. As imagens da se??o transversal dos filmes de TiO2/In2O3 cristalizados a 700?C indicam espessuras bem uniformes variando de 262 a 708nm entre amostras. A atividade fotocatal?tica dos filmes foi avaliada atrav?s da degada??o do corante azul de metileno, os resultados indicaram que os filmes conferiram boa atividade fotocatal?tica na decomposi??o do azul de metileno. Os espectros de fotoluminesc?ncia apresentaram emiss?es correspondentes na regi?o do azul, resultado confirmado atrav?s do diagrama de cromaticidade. / In recent decades it has seen a huge interest in the study of nanostructured ceramic materials with photocatalytic and photoluminescent properties. A precursor is titanium dioxide (TiO2) having optical properties but has a high value of band gap (3.2 eV), combining them with other oxides such as indium oxide (In2O3) intensify their properties, as the In2O3 it has a smaller band gap (2.8 eV), and presents the visible absorption being effective to increase the absorption of the TiO2. In this work the spin-coating method was used in the deposition of multilayer thin films of TiO2 / In2O3. In the preparation of films, resins used were obtained by the complex polymerization method (CPM) which had a viscosity of 20cps adjusted. The resins were deposited on the silicon substrate (Si) ranging in 4, 8 and 16 layers there upon were crystallized at different temperatures 300?C, 500?C and 700?C. The characterization of the films was made by diffraction of X-rays (XRD), scanning electron microscopy, field emission (SEM-FEG), atomic force microscopy (AFM), spectroscopy in the UV-Visible region (UV- Vis) and photoluminescence measurements (PL). The results of X-ray diffraction confirmed the formation of anatase TiO2 with and In2O3 phase, there is no chemical interaction between the oxides of the films. The images obtained by atomic force microscopy showed well densified film with average grain size ranging from 15 to 35 nm. The images of the cross section of the film TiO2/In2O3 crystallized at 700?C indicated a uniform thickness ranging from 262 to 708nm between samples. The photocatalytic activity of the films was evaluated by the degradation of methylene blue dye, the results indicated that the film gave good photocatalytic activity in the decomposition of methylene blue, and increasing the number of layers had no significant influence on the increase in activity photocatalytic. The films were recycled and reused for three cycles photobleaching. The results were quite significant, as demonstrated the feasibility of reuse of thin films in the dye photobleaching. The photoluminescent properties of the films was studied at room temperature using excitation wavelength of 350 nm. The thin films studied had broadband issue. A high photoluminescent intensity was observed for the films annealed at 700 ? C in the different variations of the layer numbers. From the results obtained it was observed the feasibility of using the thin film as a photocatalytic material.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-04-17T21:26:30Z No. of bitstreams: 1 MaraTatianeDeSouzaTavares_TESE.pdf: 3624533 bytes, checksum: fd1f8f479ff20180ca99cd3c488a4834 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-04-18T21:34:42Z (GMT) No. of bitstreams: 1 MaraTatianeDeSouzaTavares_TESE.pdf: 3624533 bytes, checksum: fd1f8f479ff20180ca99cd3c488a4834 (MD5) / Made available in DSpace on 2017-04-18T21:34:42Z (GMT). No. of bitstreams: 1 MaraTatianeDeSouzaTavares_TESE.pdf: 3624533 bytes, checksum: fd1f8f479ff20180ca99cd3c488a4834 (MD5) Previous issue date: 2016-07-26 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Atualmente vem sendo investigada uma nova classe de materiais inorg?nicos que surgem como uma op??o promissora com alto desempenho em diferentes aplica??es, tais como fotocatal?ticas e bactericidas. O Hidr?xido de ?ndio (III) ? um semicondutor que apresenta bom desempenho em propriedades ?ticas e t?m gerado intensas investiga??es para compreens?o de novas aplica??es. A dopagem de semicondutores com diferentes elementos ? conhecida por afetar grandemente muitas das suas propriedades b?sicas. Para obter as propriedades desejadas, atualmente muitos pesquisadores estudam s?ntese de semicondutores puros e dopados, em uma grande variedade de materiais. Neste trabalho, estruturas cristalinas de hidr?xido de ?ndio puro e dopado com ?ons de zinco e ?ons de prata foram sintetizadas pelo m?todo hidrot?rmico assistido por micro-ondas (HM) utilizando patamar de tratamento hidrot?rmico de 30 minutos. As amostras foram caracterizadas por difra??o de raios-X (DRX), microscopia eletr?nica de varredura com emiss?o de campo (MEV-FEG), fotoluminesc?ncia (FL) e espectroscopia UV-vis?vel (UV-vis). Para verificar a aplicabilidade foram realizados nas amostras de In1-x(OH)3Znx teste fotocatal?tico e nas amostras de In1-x(OH)3Agx teste bactericida. Os resultados de difra??o de raios-X confirmaram a forma??o da fase c?bica de In(OH)3, mesmo com o teor m?ximo de dopantes (0,04 de Zn+2 e 0,04 de Ag+). Imagens de MEV mostraram que as amostras de In(OH)3 puro exibe morfologia na forma de cubos com diferentes tamanhos de part?culas, j? nas amostras dopadas com ?ons de Zn+2 e Ag+ houve altera??es significativas na morfologia apresentando compostos agregadas com diferentes tamanhos de part?culas. Os espectros de fotoluminesc?ncia apresentaram diminui??o na intensidade com o aumento da concentra??o de ?ons de Zn+2 na matriz hospedeira, j? as amostras dopadas com 0,02 e 0,04 de ?ons de Ag+ apresentam um desvio para o vermelho. Os espectros de reflect?ncia de UV-vis indicaram que a dopagem com ?ons de Zn+2 e Ag+ causaram uma diminui??o na banda de gap com o aumento da dopagem de 0 para 0,04 de Zn+2/Ag+. No teste fotocatal?tico das amostras de In1-x(OH)3Znx (x=0,04) o corante rodamina B (RhB) degradou em apenas 16 minutos sob irradia??o UV. As amostras do In(OH)3 puro degradaram o corante ap?s 30 minutos sob irradia??o UV. Estes resultados indicaram que, mesmo sem qualquer dopagem, a efici?ncia desse semicondutor na fotodegrada??o do rodamina B (RhB) ? alta. A atividade bactericida das amostra de In1-x(OH)3Agx foi avaliada utilizando bact?rias Gram negativa (Escherichia coli) e bact?rias Gram positivas (Staphylococcus aureus). A presen?a de uma zona de inibi??o indica claramente o efeito antibacteriano das amostras dopadas com Ag+ para ambos os tipos de bact?rias (E. coli e S. aureus), enquanto as amostras de In(OH)3 puro n?o apresentam qualquer efeito antibacteriano. / Currently is being investigated a new class of inorganic materials occurring as a promising option with high performance in different applications, such as photocatalytic and bactericidal. The Hydroxide of Indium (III) is a semiconductor that performs well in optical properties and have generated intense research to understand new applications. The doping of semiconductors with different elements is known to greatly affect many of their basic properties. To obtain the desired properties, currently many researchers study synthesis of pure semiconductors and doped, in a the wide variety of materials. In this work, crystal structures of pure indium hydroxide and doped zinc ions and silver ions were synthesized by hydrothermal method assisted by microwave (MAH) using hydrothermal treatment level of 30 minutes. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy, with field emission (SEM-FEG), photoluminescence (PL) and UV-visible (UV-vis). To verify the applicability were conducted on samples In1-x(OH)3Znx photocatalytic test and samples the In1-x(OH)3Agx bactericidal test. The results of X-ray diffraction confirmed the formation of cubic phase of In(OH)3 even with the maximum level of doping (0,04 Zn2+ and 0,04 Ag+). SEM pictures showed that the samples of pure In(OH)3 exhibits morphology in the form of cubes with different sizes of particles, since at the samples doped with Zn2+ and Ag+ ions were no significant changes in morphology compounds having aggregate with different sizes of particles. The photoluminescence spectra show decrease in intensity with increased concentration of Zn2+ ions in the host matrix, since the samples doped with 0,02 and 0,04 Ag+ ions have a redshift. The reflectance spectra of UV-vis indicated that doping with Zn2+ and Ag+ ions caused a decrease in the band gap with increasing doping of 0 to 0,04 Zn2+/Ag+. In the photocatalytic test sample of In1-x(OH)3Znx (x=0,04) the rhodamine dye (RhB) degraded in about 16 minutes under UV irradiation. The samples pure In(OH)3 dye degraded after 30 minutes under UV irradiation. These results indicated that even without doping, the efficiency of this semiconductor in photodegradation of rhodamine B (RhB) is high. The bactericidal activity of the sample In1-x(OH)3Agx was evaluated using Gram negative bacteria (Escherichia coli) and Gram positive (Staphylococcus aureus). The presence of a zone of inhibition clearly shows the antibacterial effect of Ag+ doped samples for both types of bacteria (E. coli and S. aureus), while samples of pure In(OH)3 show no antibacterial effect.