Made available in DSpace on 2014-06-11T19:35:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-16Bitstream added on 2014-06-13T19:44:58Z : No. of bitstreams: 1 faber_m_dr_araiq.pdf: 616939 bytes, checksum: 5db3f5c1f7c0957c9c2391a95b6380b6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os estudos de degradação do corante VAT idantreno verde oliva foram realizados empregando-se solução 5x10-5 mol L-1 do corante em meio de NaCl 0,1 mol L-1 , pH=2,0 por meio do processo fotoeletrocatalítico sobre eletrodos de filmes finos de Ti/TiO2. Após 210 min de tratamento foi obtido 100% de descoloração e 86 % de mineralização. A aplicação do método fotocatalítico nas mesmas condições experimentais leva a apenas 60% de remoção do corante, indicando que o método fotoeletrocatalítico apresenta maior eficiência que a técnica de fotocatálise. A degradação do corante ácido vermelho 8 foi investigada através de processo fotoquímico empregando irradiação UV com lâmpada germicida de 4 W e lâmpada de mercúrio de 80 W. Foi observado significativa remoção da cor, porém análises de carbono orgânico total mostraram que o processo não apresenta nenhuma mineralização da matéria orgânica. Utilizando-se lâmpada de 80 W a degradação do corante ocorre segundo reação de pseudo primeira ordem com constante de velocidade de 0,0122 min-1 . A degradação do corante vermelho 8 é mais eficiente pelo processo fotocatalítico. A oxidação fotocatalítica de solução 5x10-5 mol L-1 do corante em meio de Na2SO4 0,1 mol L-1 , pH=6,0, sobre vidro/TiO2 promoveu 100 % de remoção da cor e aproximadamente 43 % de mineralização do corante. A eficiência fotocatalítica de filmes de TiO2 suportados em substrato de vidro obtidos pelo método dip-coating foi investigada testando-se a degradação do corante ácido vermelho em filmes obtidos variando-se os parâmetros: número de etapas de recobrimento, velocidade de deposição e temperatura de calcinação. O filme que mostrou maior eficiência fotocatalítica na degradação do corante ácido vermelho 8, foi construído com 1 depósito de TiO2, velocidade de recobrimento de 50 mm/min e temperatura... / Studies of degradation of the dye VAT Indanthrene olive green were performed using solution was 5x10-5 mol L-1 dye in NaCl 0.1 mol L-1 , pH = 2.0 through the process photoelectrocatalytic thin-film electrodes Ti/TiO2. After 210min of treatment was obtained 100% discoloration and 86% of mineralization. The application of the photocatalytic the same experimental condition leads to 60% removal of dye, indicating that the method photoelectrocatalytic is more efficient than the technique of photocatalysis. The degradation of acid red dye 8 was investigated by photochemical process using irradiation with UV germicidal lamp 4W and mercury lamp of 80W. Have been observed significant removal of color, but the analysis of carbon organic total no shows mineralization of organic matter. Using 80W lamp degradation of the dye is second reaction under pseudo first order rate constant of 0.0122 min-1 . The degradation of the red dye 8 is more efficient for the photocatalytic process. The photocatalytic oxidation of solution 5x10-5 mol L-1 dye in the midst of Na2SO4 0.1 mol L-1 , pH= 6.0 on glass/TiO2 promoted 100% removal of color and approximately 43% mineralization of the dye. The efficiency of photocatalytic TiO2 films supported on glass substrate obtained by dip-coating method was investigated by testing the degradation of acid red dye in films obtained by varying the parameters: number of steps of coating, deposition rate and temperature calcination. The film showed better photocatalytic degradation of dye Acid Red 8, was built with 1 deposit TiO2, coating speed of 50 mm/min and calcination temperature of 350°C film. Under these conditions the degradation of the dye second reaction is pseudo first-order rate constant of degradation of k = 0.121 min-1 . Therefore, it is concluded that the technique of photolysis and photocatalysis can be an excellent alternative to decolorize... (Complete abstract click electronic access below)

The synthesis and extensive spectroscopical characterization of novel phthalocyanines are reported. The new compounds were characterized by elemental analysis, FT-IR, ¹HNMR, mass spectrometry and UV–Vis spectroscopy. The new phthalocyanines showed remarkable photophysicochemical behaviour. The novel phthalocyanines were then conjugated to nanoparticles, silver and ZnO. The coupling of the novel Pcs to nanoparticles was through covalent bonding and ligand exchange. These conjugates were supported onto electrospun polystyrene fibers and chitosan microbeads for use as photocatalysts. The efficiency of the immobilized Pcs and Pc-nanoparticles was assessed by the phototrasfromation of organic pollutants, methyl orange and Rhodamine 6G as model dyes. Upon conjugating phthalocyanines to nanoparticles, there was a great increase in the rate of photodegradation of the model dyes. The photodynamic activity of the novel phthalocyanines upon conjugating to nanoparticles and selected targeting agents is also reported. The targeting agents employed in this study are folic acid and polylysine. Conjugating the phthalocyanines to folic acid or polylysine improved the solubility of the phthalocyanines in aqueous media. The potency of the conjugates was investigated on breast (MCF-7), prostate and melanoma cancer cell lines. The phthalocyanines showed no toxicity in the absence of light. However, upon illumination, a concentration dependent cellular decrease was observed.

O presente trabalho tem o objetivo de investigar a obtenção de hidrogênio a partir de soluções de etanol em água, por fotocatálise, usando-se catalisadores a base de óxido de zinco (ZnO). Nestes estudos foram empregados cinco catalisadores ZnO, sendo um comercial e os demais preparados através de diferentes metodologias encontradas na literatura. Os catalisadores foram caracterizados por área BET, DRX e FRX, e a investigação preliminar da atividade destes catalisadores foi feita através de ensaios de degradação fotocatalítica de rodamina B em reator slurry em batelada, onde foram avaliadas a taxa de reação e a remoção de corante. Os ensaios para a produção fotocatalítica de hidrogênio foram realizados em um reator de quartzo, operado em batelada com catalisador em suspensão e atmosfera inerte de nitrogênio. A solução foi irradiada por uma série de seis lâmpadas compactas de luz negra. Ao longo dos testes, amostras das fases líquida e gasosa foram coletadas e analisadas para identificação do consumo de etanol e produção de hidrogênio usando-se, respectivamente, Carbono Orgânico Total (TOC) e Cromatografia Gasosa (GC). Resultados preliminares mostraram que os catalisadores ZnO comercial e sintetizado (ZnO Merck e ZnO-B) apresentam atividade fotocatalítica e desempenho similares aos do TiO2 para a degradação da rodamina B. Contudo, estes mesmos catalisadores mostraram-se pouco ativos para a produção fotocatalítica de hidrogênio, com desempenho bastante inferior ao do TiO2 nas mesmas condições. Foi possível observar que o maior rendimento em hidrogênio ocorre para baixas concentrações de catalisador (0,05 gL[elevado a potência menos]1) e elevadas concentrações de etanol, sendo pouco dependente do pH. / This work aims to investigate the hydrogen production from ethanol-water solutions through photocatalysis, using zinc oxide catalysts (ZnO). Five ZnO catalysts were employed in this work; one was a commercial catalyst, while the others were prepared according to different methodologies reported in the literature. The catalysts were characterized by BET, XRD and XRF, and the preliminary investigation of their activity was done by photocatalytic degradation of rhodamine B, through the evaluation of the reaction rate and dye removal. Tests for photocatalytic hydrogen production were carried out in a quartz slurry batch reactor under nitrogen, irradiated by a set of six compact UV light bulbs. During the tests, gas and liquid samples were collected and analyzed in order to identify the consumption of ethanol and hydrogen production using, respectively, Total Organic Carbon (TOC) and Gas Chromatograph (GC). Preliminary results showed that the synthesized and commercial ZnO catalysts (ZnO-B and ZnO Merck) present photocatalytic activity and performance similar to TiO2 for the rhodamine B degradation. However, the ZnO catalysts presented lower performance when compared with TiO2 for hydrogen production, under the same conditions. It was observed that the highest hydrogen yield occurs for low concentrations of catalyst (0.05 gL1) and high concentrations of ethanol, being less dependent on pH.

abstract: Contamination of drinking water supplies from oxo-anion pollutants necessitates treatment prior to potable use. This dissertation aims to inform and improve light delivery (emission spectra, radiant intensity, reactor configuration) in order to enhance the photocatalytic reduction of hexavalent chromium (Cr(VI)) and nitrate, two common oxo-anions in drinking water, and photocatalytic oxidation of two model organic pollutants (methylene blue, (MB) and para-chlorobenzoic acid (pCBA)). By varying the photon fluence dose, two metrics (contaminant quantum yield (Φ), and electrical energy per order (EEO)) were used to assess photocatalytic reactor performance. A detailed literature review and experimental results demonstrated how different irradiance sources with variable intensity and emission spectra synergistically enhanced contaminant removal by a coupled photolytic/photocatalytic reaction mechanism. Cr(VI) was photocatalytically reduced on TiO2 and formed Cr(OH)3(s) in a large-scale slurry reactor, but Cr(III) was then photolyzed and reformed Cr(VI). UV light also led to photo-aggregation of TiO2 which improved its recovery by the ceramic membrane within the reactor. For nitrate reduction, light source emission spectra and fluence dose delineate the preferred pathways as intermediates were reduced via wavelength-dependent mechanisms. HONO was identified as a key nitrate reduction intermediate, which was reduced photocatalytically (UV wavelengths) and/or readily photolyzed at 365nm, to yield nitrogen gases. Photocatalytic nitrate reduction efficiency was higher for discrete wavelength irradiation than polychromatic irradiation. Light delivery through aqueous media to the catalyst surface limits efficiency of slurry-based photocatalysts because absorption and scattering of light in nanomaterial slurries decreases effective photon transmittance and minimizes photolytic reactions. The use of optical fibers coupled to light emitting diodes (OF-LED) with immobilized catalyst demonstrated higher performance compared to slurry systems. OF-LED increased Φ for MB degradation by increasing direct photon delivery to the photocatalyst. Design of OF-LED reactors using bundled optical fibers demonstrated photocatalytic pCBA removal with high Φ and reduced EEO due to increased surface area and catalytic sites compared to single OF/LED couples. This work advances light delivery as well as the suspension and attachment of nanoparticles in photocatalytic water treatment for selective transformation of oxo-anions and organic compounds to innocuous species. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2017

This thesis is focused on developing metal-organic and organic molecules for photocatalytic water splitting and carbon dioxide reduction. In chapter 1, an overview of hydrogen production, dye-sensitized solar cells and carbon dioxide reduction are provided. The development history and reaction mechanisms of catalytic systems are introduced along with the typical examples in each field. The applications of both metal-organic and organic compounds are covered. In chapter 2, nine molecular organic photosensitizers were designed and synthesized. The nine molecules were employed as the photosensitizing reagent in the fabrication of dye-sensitized solar cells and applied in photocatalytic water reduction via coupling with TiO2 semiconductors and Pt co-catalyst. The highest turnover number (TON) of 10200 was achieved by organic photosensitizer 1g for hydrogen generation. The effect of alkyl chains and triarylamine donor moiety to the photocatalytic performance was investigated. A shorter alkyl chain was found to favor the reaction due to a lower hydrophobicity which in turn may block the interaction between the photocatalyst and water molecules. Besides, the triarylamine donor units facilitated high hydrogen generation rates by reducing the contact between catalytic active sites and the oxidized form of sacrificial reagents. In chapter 3, five earth-abundant metal complexes were synthesized to serve as the catalyst and CdS nanorods (NRs) were prepared to be the photosensitizer for the photocatalytic water reduction. A cobalt dithiolene complex (2a) achieved a TON of 30635 in 20 h under the blue light irradiation at a concentration of 10 µM. A new complex 2c also gave a high TON of 12375 under the same conditions and its TON was further improved to 115213 in 87 h by reducing the concentration of catalyst by ten times. The size effect of CdS NRs was investigated and larger nanoparticles exhibited higher hydrogen production rates. In chapter 4, ten iridium(III) complexes were synthesized and used as dual-functional molecules in photocatalytic carbon dioxide reduction by acting as both the photosensitizing reagent as well as the catalyst. The best performance was achieved by 3j, giving a TON of 230 under the irradiation of blue LED. A push-pull effect brought by trifluoromethyl and methoxy group sucessfully enhanced the carbon dioxide reduction efficiency. The hydrophobicity of n-butyl chain also provided effective protection to the active sites of reaction intermediate. Additional steric hindrance was found to extend the lifespan of photocatalytic systems but led to a drop in the overall conversion efficiency. Chapter 5 summarizes the specific synthetic procedures and characterization parameters of the molecules in chapters 2-4.

La première partie de ce travail est consacrée à l’évaluation de l’efficacité photocatalytique de plusieurs semiconducteurs commerciaux. La comparaison est basée sur la détermination de leurs propriétés physiques : diamètre des particules, taille des cristallites, structure cristallographique, propriétés électroniques, composition chimique ainsi que capacité d’adsorption. L’efficacité photocatalytique est testée sur le phénol, un polluant modèle. Alors que ZnO présente une activité photocatalytique légèrement supérieure à celle des différents TiO2 étudiés, c’est pour le TiO2 P25 que la plus faible résistivité a été observée. C’est donc au sein de ce dernier que la circulation électronique est la meilleure. L’existence de différentes formes cristallographiques pour le TiO2 est démontrée être également un autre paramètre fondamental gouvernant la réactivité. Si la partition anatase/rutile (80/20%) est donc importante, le fait que le TiO2-P25 soit formé d'un seul cristallite le semble tout autant, car c’est tout le grain qui peut être considéré comme actif.Une seconde partie est dédiée à l’étude de la dégradation photocatalytique d’un colorant, le Vert Cibacron (RG12) utilisé dans l’industrie textile. Le travail est réalisé en suspension aqueuse en présence de dioxyde de titane TiO2-P25. La décoloration de la suspension est effective après 90min de traitement et s’accompagne d’une minéralisation partielle de 60% pour une gamme de concentration initiale en RG12 entre 10-40 mgL-1. Pour déterminer le mécanisme général de la photocatalyse, des investigations thermodynamiques et cinétiques ont été menées sur l’adsorption du colorant sur TiO2-P25. La chimisorption s’est avérée être le processus spontané endothermique majoritaire se déroulant à la surface du photocatalyseur. La cinétique d’adsorption suit globalement une loi de pseudo-ordre deux accompagnée d’un mécanisme de diffusion intraparticulaire observé aux fortes concentrations (80-120 mgL-1) mettant en avant les mésopores du matériau. Un modèle faisant intervenir une adsorption compétitive des espèces à la surface du photocatalyseur a été élaboré. Les molécules de colorant, de sous-produits de dégradation, les molécules d’eau et ions hydroxydes, ainsi que le dioxygène présent en solution et à la surface du TiO2 sont supposés entrer en compétition vis à vis des mêmes sites d’adsorption. Il est alors observé que l’inverse de la constante de dégradation photocatalytique du colorant dépend d’un polynôme du second degré de la concentration initiale du colorant de départ.Afin de contrecarrer le problème récurrent de la filtration des suspensions aqueuses de TiO2, la fixation de TiO2 par la méthode PMTP sur des plaques de verre a été étudiée. La caractérisation des dépôts par MEB et DRX a permis de montrer que ceux-ci étaient homogènes. Les performances du TiO2 supporté ont été comparées au procédé photocatalytique classique en suspension aqueuse sur le colorant Vert Cibacron dans un réacteur à recirculation de 500 mL dont les conditions optimales de fonctionnement ont été déterminées. Le modèle précédent de compétition d’adsorption des espèces à la surface du photocatalyseur, s’est montré adapté à décrire les résultats expérimentaux comparativement au modèle de Langmuir-Hinshelwood.Enfin, le couplage photocatalyse/sonolyse a été examiné pour la dégradation du vert Cibacron. Le dosage des espèces actives générées par chaque technique a été réalisé. Une synergie est apparue lors du couplage de la photocatalyse sous irradiation solaire en présence d’ultrasons 500 kHz. / The first part of this work is dedicated to the evaluation of the photocatalytic efficiency of semiconductors ZnO, TiO2 P25, and two other titanium dioxides (anatase 100%). The comparison was based on determining the physical properties of photocatalysts, mainly: the particle diameter, crystallite size, crystallographic structure, electronic properties, chemical composition and the adsorption capacity. The photocatalytic efficiency was tested with phenol as target molecule. While comparable photocatalytic activity was found with ZnO and TiO2 P25, the lowest resistivity was observed with TiO2 P25, which means that a better electronic circulation occurs in this last photocatalyst compared to ZnO, but also that there is another fundamental parameter governing the reactivity. Under the same crystallographic form, 100% anatase, the photoreactivity of TiO2 is slightly higher with the photocatalyst having the lowest grain's diameter. The highest photoreactivity of TiO2 P25 can be explained by the partition anatase/rutile (80/20%), a higher electronic circulation and by the fact that TiO2 P25 is formed from a single crystallite, where any grains are considered as photoactive. Second part concerns the photocatalytic degradation of dye Cibacron Green (RG12) used by textile industry, in aqueous suspension in the presence of titanium dioxide TiO2 P25. Discoloration of the suspension was effective after 90min treatment with a partial mineralization 60% of the initial dye (10-40 mgL-1). To determine the general mechanism of the photocatalytic process, especially if the surface of the material is involved or not, thermodynamic and kinetic investigations were investiagted on adsorption. Chemisorption was found to be the majority endothermic spontaneous process occurring on the surface of the photocatalyst. Moreover, the adsorption kinetics follows a pseudo-second order law with a intraparticle diffusion mechanism which was observed at higher concentrations (80-120 mgL-1) highlighting the mesopores of TiO2. As the Langmuir-Hinshelwood, Ollis and Direct –Indirect models were enable to fully describe our experimental results, a new model involving a competitive adsorption of species on the surface of the photocatalyst was developed. Dye molecules, byproducts of degradation, water molecules, hydroxide ions and the oxygen present in solution are assumed to compete with respect to the same sites of adsorption at the TiO2 surface. The model showed that the inverse of the constant of the dye photocatalytic degradation depended on a second degree polynomial of the initial concentration of initial dye. Binding experiments of TiO2 on glass plates by the method PMTP were carried out in order to work with supported TiO2 in a dedicated reactor having a recirculation of 0.5 L and where optimum operating conditions were determined. Characterization of deposits by SEM and XRD showed that they were homogeneous with a density of 0.26 mg TiO2/cm². Performances of the supported TiO2 were compared to the conventional photocatalytic process in aqueous suspension by studying the discoloration of the previous dye Cibacron green. The competitive adsorption model elaborated well described experimental results. Final examination was done by coupling photocatalysis and sonolysis for the degradation of Cibacron Green. The determination of the active species generated by each technique was performed. A synergy was observed under solar irradiation of TiO2 in the presence of 500 kHz ultrasound which could provide from an extensive mass transfer of the dye on the photocatalyst induced by ultrasounds.

Made available in DSpace on 2014-06-11T19:23:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-21Bitstream added on 2014-06-13T19:49:42Z : No. of bitstreams: 1 pegler_gf_me_araiq.pdf: 1754677 bytes, checksum: 933e5a43ec264378906ee0708203a98e (MD5) / Pelo presente trabalho foram obtidos fotocatalisadores formados por composições binárias e ternárias dos óxidos comerciais TiO2 anatase (marca Synth), SnO2 rutilo (marca Cesbra) e Ag2O (marca Vetec). Anteriormente à preparação dos materiais ternários houve a preparação e estudo de três composições binárias preparadas em três temperaturas distintas de calcinação (400 °C, 600 °C, 800 °C), formadas por TiO2 + SnO2 variando nas razões em porcentagem molar de 25/75, 50/50, 75/25 respectivamente. O material binário TiO2 + SnO2 (75/25 - 400 °C), assim como TiO2 puro foram modificados pela adição de Ag2O nas composições em porcentagem molar de 0,02; 0,1; 0,2 e 1,0. Os materiais foram obtidos pelo método de mistura de óxidos e homogeneização em moinho de bolas rotativo com posterior tratamento térmico à temperatura de 400 °C por 4 horas. Os desempenhos fotocatalíticos desses materiais foram monitorados através de ensaios de descoloração dos corantes orgânicos Rodamina B e Azul de Metileno sob iluminação de luz ultravioleta em reator fotocatalítico desenvolvido neste trabalho. Os picos de absorção molecular dos corantes foram monitorados durante os ensaios fotocatalíticos através de medidas de espectrofotometria UV-vis. Os fotocatalisadores foram caracterizados quanto às fases cristalinas por difração de Raios X, quanto à área superficial específica S(BET) em equipamento de análise de adsorção de N2, quanto à morfologia dos pós por FEG-SEM e quanto à composição química superficial por análise de XPS. Os fotocatalisadores ternários apresentaram cinética reacional superior ao encontrado para o óxido comercial referência TiO2 P25 (marca Degussa) nos ensaios com Rodamina B. Nos ensaios com Azul de Metileno foram obtidos resultados de cinética próximos do encontrado para o óxido... / In this study were obtained photocatalysts consisting of binary and ternary compositions of the commercial oxides TiO2 (Synth), SnO2 (Cesbra) and Ag2O (Vetec). Prior to the preparation of ternary materials there was the preparation and study of three binary compositions prepared in three different calcination temperatures (400 °C, 600 °C, 800 °C) formed by TiO2 + SnO2 ranging in percentage molar ratios of 75/25, 50/50, 75/25 respectively. The binary material TiO2 + SnO2 (75/25 - 400 °C), as well as pure TiO2, has been modified by the addition of Ag2O in 0.02, 0.1, 0.2 and 1.0 molar percentage compositions. The materials were obtained by the oxide mixture technique and homogenization in a rotary ball mill with subsequent thermal treatment at 400 °C for four hours. The photocatalytic performances of these materials were studied by testing of Rhodamine B and Methylene Blue photobleaching under the activation of materials by ultraviolet light in photocatalysis reactor developed in this work. Molecular absorption peaks of the dyes during the tests of photobleaching were monitored by UV-vis spectrophotometry. Crystal structure patterns of the powders were examined by X-ray diffraction (XRD), BET surface area measurement were carried out by using N2 as the adsorptive gas, the morphology analysis were performed by scanning electron microscopy (FEG-SEM) and the elemental chemical composition at the powder surfaces was analysed by XPS analysis. The kinetic analysis showed that the ternary materials had better results than commercial reference oxide TiO2 P25 (Degussa) in the tests with Rhodamine B. When comparing the Methylene Blue performances realized with ternary and TiO2 + Ag2O compositions, the kinetic for both were near the P25. It was also checked photocatalytic activation by sunlight... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:24:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-02-13Bitstream added on 2014-06-13T20:52:28Z : No. of bitstreams: 1 giovanni_g_me_botfca.pdf: 297824 bytes, checksum: b42e7912f9eb1618cd0ccc7c41f0c23c (MD5) / As águas residuárias dos processos de extração vegetal para fins farmacêuticos apresentam elevada DQO (Demanda Química de Oxigênio) e orgânicos persistentes que não são eliminados pelos tratamentos de resíduos líquidos convencionais. Atualmente, a fotocatálise heterogênea vêm se destacando como processo de oxidação avançado (POA) capaz de mineralizar compostos persistentes responsáveis pela poluição do meio ambiente aquático. Este trabalho tem o propósito de descontaminar o efluente semi-tratado de um indústria de extração vegetal, situada na região de Botucatu, São Paulo, Brasil; para seu posterior reuso, a fotocatálise (TiO2 em suspensão) foi aplicada. Foram realizados testes com variação do pH da amostra em que se obteve maior eficiência de fotodegradação em pH 4,0. Foi testado a adição de persulfato de potássio em várias concentrações, constatando que a adição 0,1 g L-1 favorece a degradação dos poluentes mais persistentes remanescentes do efluente semi-tratado. Finalmente, com o objetivo de remover o TiO2 da suspensão foram realizados testes de coagulação-floculação, na presença de sulfato de alumínio e pH 4,0. O tempo de decantação do material em suspensão foi de 30 minutos, DQO final de 2,5 mg O2 L-1 e a turbidez final de 2 NTU. A fotocatálise contribuiu para a remoção de tóxicos persistentes, redução da DQO, eliminação de odores e redução da turbidez do efluente. / The wastewater of vegetable extraction process (for pharmaceutical use) present increased DQO (Qhemistry Demand of Oxigen) and bio-recalcitrant organic contaminant that are not eliminated by convencional wastewater treatments. Presently, the heterogen photocatalysis is been outstanding as advanced oxidation process (AOP) capable of decaying of recalcitrant compounds, responsible for the pollution of the aquatic environment. This paper have to purpose of descontaminate the pretreated wastewater by vegetable extraction industry, located in Botucatu region, São Paulo, Brazil; the photocatalysis (TiO2 suspension) was applicated, for it is future reuse. Experiments were carried out with various pH samples with efficient results of photodegradation in pH 4,0. Experiments with the peroxydisulphat addition have done in various concentrations, concluding that it is minimum addition (0,1 g L-1) favours the degradation speed of the moust recalcitrants polluants of the pretreated wastewater. Eventually, experiments of coagulation-floculation have been done to remove the TiO2 (0,5 g L-1) from the suspension, in presence of aluminium sulphate (0,2 g L-1) and pH 4,0. The time of decantation of the suspension material was 30 minutes, the final turbidity 2 NTU and final DQO 2,5 mg O2 L-1. The photocatalysis contributed to remove recalcitrant organic compounds, to reduce the DQO, eliminated the smell and to redecue the wastewater turbidity.

O uso de energias renováveis como a energia solar para a produção de gás hidrogênio (H2), por meio do processo fotocatalítico da quebra da molécula de água, é uma alternativa promissora às fontes de energias convencionais. Neste contexto, a produção de filmes finos nanoestruturados de diferentes materiais é uma aplicação que pode aliar a fotocatálise e a nanotecnologia. Assim, o principal objetivo deste trabalho foi avaliar o efeito de diferentes concentrações de ácido tetracloroaurico (HAuCl4) para incorporação de nanopartículas de ouro (NPs Au) na produção de H2, a partir de filmes finos suportados em celulose bacteriana (CB), produzidos através da técnica camada por camada utilizando os polieletrólitos fracos, hidrocloreto de polialilamina (PAH) e poli(ácido acrílico) (PAA), combinados com dióxido de titânio (TiO2). Por meio das técnicas de espectroscopia de absorção molecular na região do ultravioleta e visível (UV-Vis), difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia de infravermelho foi possível verificar a absorção da CB na região do UV, os picos em 14,6º, 16,6º e 22,6º, a superfície constituída de fibras e as bandas características da CB, respectivamente. A área superficial específica de 1,57 m2 g-1 foi encontrada para a CB. A absorção na região do UV das soluções de HAuCl4 e TiO2 foram determinadas por UV-Vis. Através da técnica de DRX, calculou-se o tamanho médio do cristalito do TiO2 que foi de ~5 nm corroborando com a microscopia eletrônica de transmissão (MET). O TiO2 também foi caracterizado por fluorescência molecular, MEV e área superficial específica. O potencial zeta foi utilizado para analisar as soluções poliméricas (PAH e PAA) e a solução de TiO2. Os filmes de diferentes concentrações de HAuCl4 (1,25 mmol L-1, 2,5 mmol L-1 e 5 mmol L-1) e com diferentes tempos de luz UV (6h, 12h, 24h, 24h, 48h e 96h) foram analisados por cromatografia gasosa (CG). Destes filmes, os que mais produziram H2 em cada concentração de HAuCl4 (c1-24 / concentração de 1,25 mmol L-1 e 24h de luz UV), (c2- 6 / concentração de 2,5 mmol L-1 e 6h de luz UV) e (c3-24 / concentração de 5 mmol L-1 e 24h de luz UV), foram caracterizados antes e depois da fotocatálise. Através do UV-Vis, foi possível observar a presença de NPs Au e TiO2 nos filmes. Por DRX, notou-se os picos da CB, do TiO2 (25,3º) e do Au (38,18º e 44,5º) nos filmes. No MEV foi possível observar que o filme (c1-24) possuia grãos de Au dispersos na matriz e a presença de Ti em toda a superfície sem aglomerações, revelando-se como um filme homogêneo comparado aos filmes (c2-6) e (c3-24). Pela técnica de MET, analisou-se a morfologia, tamanho e distribuição das NPs Au nos filmes revelando valores em escala manométrica. O filme (c1-24) apresentou menores tamanhos de NPs Au (9 nm). Área superficial específica, perfilometria, Espectroscopia de Emissão Óptica de Descarga Luminescente e Espectrometria de emissão óptica com plasma também foram analisados para avaliar o efeito das concentrações e tamanhos de NPs Au nos filmes. O filme com menor concentração de HAuCl4 (c1-24), o qual tinha NPs Au menores que em maior contato com a superfície do TiO2 produziu mais H2, foi analisado por CG para aperfeiçoar o melhor desempenho na produção de H2 variando alguns parâmetros como reutilização do filme (c1-24a) e (c1-24b), alteração de substrato (c1-24d), aumento de camadas (c1-24f) e filme sem polímeros (c1-24g). Analisando todas as variações dos parâmetros foi concluído que o filme (c1-24) produziu 29,12 μmol h-1cm2 de H2 apresentando uma melhor atividade fotocatalítica. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2017-05-10T16:47:00Z No. of bitstreams: 1 Tese Nicolle Dal Acqua.pdf: 2359937 bytes, checksum: 79a564bfa513c80ed882f203002fc4ca (MD5) / Made available in DSpace on 2017-05-10T16:47:00Z (GMT). No. of bitstreams: 1 Tese Nicolle Dal Acqua.pdf: 2359937 bytes, checksum: 79a564bfa513c80ed882f203002fc4ca (MD5) Previous issue date: 2017-05-10 / Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS. / The use of renewable energy such as solar energy to produce hydrogen gas (H2), through the photocatalytic process of breaking the water molecule, is a promising alternative to conventional energy sources. In this context, the production of nanostructured thin films of different materials is an application that can combine photocatalysis and nanotechnology.Thus, the main objective of this work was to evaluate the effect of different concentrations of tetrachlorouric acid (HAuCl4) for the incorporation of gold nanoparticles (Au NPs) in H2 production from thin films supported on bacterial cellulose (BC), produced through of the technique layer by layer using the weak polyelectrolytes, polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) combined with titanium dioxide (TiO2). Through the techniques of molecular absorption spectroscopy in the ultraviolet and visible (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (FTIR), it was possible to verify the absorption of BC in the UV region, the peaks at 14.6º, 16.6º and 22.6º, the fiber surface and the characteristic bands of BC, respectively. The specific surface area of 1.57 m2 g-1 was found for CB. Absorption in the UV region of the HAuCl4 and TiO2 solutions were determined by UV-Vis. By means of the XRD technique, the average crystallite size of the TiO2 was calculated which was ~5 nm corroborating with transmission electron microscopy (TEM). TiO2 was also characterized by molecular fluorescence, SEM and specific surface area. The zeta potential was used to analyze the polymer solutions (PAH and PAA) and the TiO 2 solution. The films with different concentrations of HAuCl4 (1.25 mmol L-1, 2.5 mmol L-1 and 5 mmol L-1) and with different UV light times (6h, 12h, 24h, 24h, 48h and 96h) were analyzed by gas chromatography (GC). Of these films, the ones that most produced H2 at each concentration of HAuCl4 (c1-24 / concentration of 1.25 mmol L-1 and 24h of UV light), (c2-6 / concentration of 2.5 mmol L-1 and 6h of UV light) and (c3-24 / concentration of 5 mmol L-1 and 24h of UV light) were characterized before and after photocatalysis. Through the UV-Vis, it was possible to observe the presence of Au and TiO2 NPs in the films. By XRD, the peaks were noted of CB, TiO2 (25.3 °) and Au (38.18 ° and 44.5 °) in the films. In the SEM it was observed that the film (c1-24) had Au grains dispersed in the matrix and the presence of Ti on the whole surface without agglomerations, revealing as a homogeneous film compared to the films (c2-6) and (c3-24). Using the MET technique, the morphology, size and distribution of Au NPs were analyzed in the films revealing values in manometric scale. The film (c1-24) presented smaller sizes of Au NPs (9 nm). Specific surface area, perfilometry, Glow-discharge optical emission spectroscopy (GD-OES) and inductively coupled plasma (ICP-OES) were also analyzed to evaluate the effect of concentrations and sizes of Au NPs in the films.The film with lower concentration of HAuCl4 (c1-24), which had Au NPs less than in greater contact with the surface of TiO2 produced more H2, was analyzed by CG to improve the best performance in H2 production varying some parameters as reuse of the film (c1-24a) and (c1-24b), substrate change (c1-24d), increase of layers (c1-24f) and film without polymers (c1-24g). Analyzing all the variations of the parameters it was concluded that the film (c1-24) produced 29.12 μmol h-1 cm2 of H2 presenting a better photocatalytic activity.

Orientador: Leinig Antônio Perazolli / Banca: Rossano Gimenes / Banca: Alberto Adriano Cavalheiro / Resumo: Pelo presente trabalho foram obtidos fotocatalisadores formados por composições binárias e ternárias dos óxidos comerciais TiO2 anatase (marca Synth), SnO2 rutilo (marca Cesbra) e Ag2O (marca Vetec). Anteriormente à preparação dos materiais ternários houve a preparação e estudo de três composições binárias preparadas em três temperaturas distintas de calcinação (400 °C, 600 °C, 800 °C), formadas por TiO2 + SnO2 variando nas razões em porcentagem molar de 25/75, 50/50, 75/25 respectivamente. O material binário TiO2 + SnO2 (75/25 - 400 °C), assim como TiO2 puro foram modificados pela adição de Ag2O nas composições em porcentagem molar de 0,02; 0,1; 0,2 e 1,0. Os materiais foram obtidos pelo método de mistura de óxidos e homogeneização em moinho de bolas rotativo com posterior tratamento térmico à temperatura de 400 °C por 4 horas. Os desempenhos fotocatalíticos desses materiais foram monitorados através de ensaios de descoloração dos corantes orgânicos Rodamina B e Azul de Metileno sob iluminação de luz ultravioleta em reator fotocatalítico desenvolvido neste trabalho. Os picos de absorção molecular dos corantes foram monitorados durante os ensaios fotocatalíticos através de medidas de espectrofotometria UV-vis. Os fotocatalisadores foram caracterizados quanto às fases cristalinas por difração de Raios X, quanto à área superficial específica S(BET) em equipamento de análise de adsorção de N2, quanto à morfologia dos pós por FEG-SEM e quanto à composição química superficial por análise de XPS. Os fotocatalisadores ternários apresentaram cinética reacional superior ao encontrado para o óxido comercial referência TiO2 P25 (marca Degussa) nos ensaios com Rodamina B. Nos ensaios com Azul de Metileno foram obtidos resultados de cinética próximos do encontrado para o óxido... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this study were obtained photocatalysts consisting of binary and ternary compositions of the commercial oxides TiO2 (Synth), SnO2 (Cesbra) and Ag2O (Vetec). Prior to the preparation of ternary materials there was the preparation and study of three binary compositions prepared in three different calcination temperatures (400 °C, 600 °C, 800 °C) formed by TiO2 + SnO2 ranging in percentage molar ratios of 75/25, 50/50, 75/25 respectively. The binary material TiO2 + SnO2 (75/25 - 400 °C), as well as pure TiO2, has been modified by the addition of Ag2O in 0.02, 0.1, 0.2 and 1.0 molar percentage compositions. The materials were obtained by the oxide mixture technique and homogenization in a rotary ball mill with subsequent thermal treatment at 400 °C for four hours. The photocatalytic performances of these materials were studied by testing of Rhodamine B and Methylene Blue photobleaching under the activation of materials by ultraviolet light in photocatalysis reactor developed in this work. Molecular absorption peaks of the dyes during the tests of photobleaching were monitored by UV-vis spectrophotometry. Crystal structure patterns of the powders were examined by X-ray diffraction (XRD), BET surface area measurement were carried out by using N2 as the adsorptive gas, the morphology analysis were performed by scanning electron microscopy (FEG-SEM) and the elemental chemical composition at the powder surfaces was analysed by XPS analysis. The kinetic analysis showed that the ternary materials had better results than commercial reference oxide TiO2 P25 (Degussa) in the tests with Rhodamine B. When comparing the Methylene Blue performances realized with ternary and TiO2 + Ag2O compositions, the kinetic for both were near the P25. It was also checked photocatalytic activation by sunlight... (Complete abstract click electronic access below) / Mestre