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N3-Dye-Induced Visible Laser Anatase-to-Rutile Phase Transition on Mesoporous TiO(2) Films

PARUSSULO, Andre L. A.; HUILA, Manuel F. G.; ARAKI, Koiti; TOMA, Henrique E.
Fonte: AMER CHEMICAL SOC Publicador: AMER CHEMICAL SOC
Tipo: Artigo de Revista Científica
ENG
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Titanium dioxide has been extensively used in photocatalysis and dye-sensitized solar cells, where control of the anatase-to-rutile phase transformation may allow the realization of more efficient devices exploiting the synergic effects at anatase/rutile interfaces. Thus, a systematic study showing the proof of concept of a dye-induced morphological transition and an anatase-to-rutile transition based on visible laser (532 nm) and nano/micro patterning of mesoporous anatase (Degussa P25 TiO(2)) films is described for the first time using a confocal Raman microscope. At low laser intensities, only the bleaching of the adsorbed N3 dye was observed. However, high enough temperatures to promote melting/densification processes and create a deep hole at the focus and an extensive phase transformation in the surrounding material were achieved using Is laser pulses of 25-41 mW/cm(2), in resonance with the MLCT band. The dye was shown to play a key role, being responsible for the absorption and efficient conversion of the laser light into heat. As a matter of fact, the dye is photothermally decomposed to amorphous carbon or to gaseous species (CO(x), NO(x), and H(2)O) under a N(2) or O(2) atmosphere, respectively.; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); PETROBRAS; PETROBRAS

Efficient and low cost devices for solar energy conversion: Efficiency and stability of some natural-dye-sensitized solar cells

PATROCINIO, A. O. T.; MIZOGUCHI, S. K.; PATERNO, L. G.; GARCIA, C. G.; IHA, N. Y. Murakami
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
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Dye-sensitized solar cells, named by us Dye-Cells, are one of the most promising devices for solar energy conversion due to their reduced production cost and low environmental impact, especially those sensitized by natural dyes. The efficiency and stability of devices based on natural sensitizers such as mulberry (Morus alba Lam), blueberry (Vaccinium myrtillus Lam), and jaboticaba`s skin (Mirtus cauliflora Mart) were investigated. Dye-Cells prepared with aqueous mulberry extract presented the highest P(max) value (1.6 mW cm(-2)) with J(sc) = 6.14 mA cm(-2) and V(oc) = 0.49 V, Photoelectrochemical parameters of 16 cm(2) active area devices sensitized by mulberry dye were constant for 14 weeks of continuous evaluation. Moreover, the cell remained stable even after 36 weeks with a fairly good efficiency. Therefore, mulberry dye opens up a perspective of commercial feasibility for inexpensive and environmentally friendly Dye-Cells. (C) 2009 Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CAPES; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise in vitro da penetração do corante azul-de-metileno na dentina radicular humana variando-se o método de impregnação .; An in vitro analysis of the methylene blue dye penetration in human radicular dentin with different methods of impregnation

Ferreira, Ronise
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/03/2006 PT
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Frente às inúmeras críticas que as metodologias de infiltração que se valem do uso de corantes têm enfrentado nos últimos decênios, o presente estudo buscou avaliar se diferentes métodos de contato com a solução de azul-de-metileno a 0,5%, têm influência ou não, na leitura da marcação propiciada por esse agente traçador na dentina radicular de dentes humanos. Propusemo-nos a analisar 6 diferentes métodos: a agitação do corante com uso do ultra-som Gnatus, a agitação com o ultra-som de limpeza, a imersão passiva, o uso de vácuo calibrado para 25 mmHg por 10 minutos e a imersão passiva, vácuo calibrado para 30mmHg e o vácuo calibrado de 650 mmHg. Para tal, foram utilizadas 60 raízes de dentes unirradiculares infiltradas pela solução de azul-de-metileno a 0,5% com pH 7 por 24 horas. Os espécimes foram clivados no sentido apico-cervical em hemipartes e seu canal preenchido com pasta Lysanda. Utilizou-se um analisador do tipo Q 550 IW da marca Leica Qwin no qual se montou uma rotina para a aquisição das imagens. Na seqüência, montou-se uma segunda rotina trabalhando com a imagem já adquirida de forma a se detectar os diferentes níveis de azul constante na cor da amostra, editada pelo operador de forma a demarcar as projeções da área de infiltração em milímetros quadrados. Os resultados foram tratados estatisticamente e...

Estudos sobre a adsorção do corante reativo preto 5 de solução aquosa  usando zeólita de  cinzas de carvão; Studies on the adsorption of reactive black 5 dye of aqueous solution using zeolite of the coal ashes

Ferreira, Patricia Cunico
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/04/2011 PT
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Nesta dissertação foi estudada a zeólita sintetizada a partir de cinzas leves de carvão como um potencial adsorvente para a remoção de corante reativo preto 5 (RP5). Ensaios cinéticos e de equilíbrio foram realizados visando obter-se as melhores condições para a adsorção deste corante, e verificou-se a influência dos seguintes parâmetros: efeito do tempo de contato, concentração inicial do corante, dose do adsorvente, pH da solução aquosa, adição dos sais NaCl e Na2SO4 e temperatura. O tempo de equilíbrio foi alcançado após 420 min. Os dados de adsorção foram ajustados melhor ao modelo cinético de pseudo-segunda-ordem. Para o sistema corante/adsorvente foi aplicado o modelo de isoterma de adsorção de Langmuir, apresentando capacidade de adsorção máxima de 0,685 mg g-1. Os dados experimentais mostraram uma alta porcentagem de remoção de 47,7 a 88,1% de RP5 sobre a zeólita. A alta porcentagem indicou que o material zeolítico apresenta potencial para ser usado como adsorvente na remoção de corantes azo reativo de indústrias têxteis. Os parâmetros termodinâmicos foram avaliados e demonstraram que o processo de adsorção do RP5 sobre a zeólita é espontâneo e exotérmico. Os experimentos adicionando os sais foram realizados para uma melhor simulação das condições reais do efluente. Os resultados mostraram que o equilíbrio de adsorção do RP5 sobre a zeólita na presença de sais foram alcançados em um tempo menor e que quanto maior a concentração dos sais na solução...

Reliability of assessing dye penetration along root canal fillings using methylene blue

Souza, Erick Miranda; Pappen, Fernanda Geraldes; Shemesh, Hagay; Bonanato-Estrela, Cristiane; Bonetti-Filho, Idomeo
Fonte: Wiley-Blackwell Publishing, Inc Publicador: Wiley-Blackwell Publishing, Inc
Tipo: Artigo de Revista Científica Formato: 158-163
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Methylene blue (MB) remains the most frequently used tracer for dye penetration tests of endodontic fillings, despite its chemical reactions with different materials. This study checked whether dye penetration displayed by MB is comparable to Rhodamine B (RB). One hundred and seventy-two root canals were filled with gutta-percha and six sealers. Samples were covered with nail varnish except for the apical area, and immersed in MB or RB solutions under negative pressure. After 24 h, roots were bisected, photographed and the maximal dye penetration recorded. Dye penetrations displayed by MB and RB were compared (Newman-Keuls test). MB and RB displayed comparable results for groups filled with AH Plus, EndoREZ and Polifil (P > 0.05). For Endofill, Sealer 26 and Sealapex, a significant lower dye penetration was observed when MB was used (P < 0.05). Laboratory tests using MB for measuring dye penetration through filled root canals can result in misleading conclusions.

A simple electroanalytical method for the analysis of the dye solvent orange 7 in fuel ethanol

Romanini, Daiane Cristina; Goncalves Trindade, Magno Aparecido; Zanoni, Maria Valnice Boldrin
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 105-109
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 06/05952-6; The purpose of this paper is to develop a simple, rapid and accurate electroanalytical method for the determination of solvent orange 7 (SO-7), commercially used as a dye marker in fuel ethanol samples. SO-7 is oxidized in a mixture of Britton-Robinson buffer with N,N-dimethylformamide (1: 1, v/v) at a glassy carbon electrode and presents a well-defined peak around +0.70 V vs. Ag/AgCl, which can be monitored by linear-scan voltammetry (LSV) and square-wave voltammetry (SWV). Using optimized parameters based on the SWV technique, it is possible to get a linear relationship between the peak current and the SO-7 dye concentration from 4.0 x 10(-6) to 18.0 x 10(-6) mol L(-1) (r = 0.995). The proposed method was successfully applied to the direct quantification of the SO-7 dye in fuel ethanol samples, which gave good average recovery for commercial samples containing 5.0 mg L(-1) and 10.0 mg L(-1) of SO-7 dye, respectively. (c) 2008 Elsevier Ltd. All rights reserved.

Analyses of the genotoxic and mutagenic potential of the products formed after the biotransformation of the azo dye Disperse Red 1

Drumond Chequer, Farah Maria; Lizier, Thiago Mescoloto; de Felicio, Rafael; Zanoni, Maria Valnice Boldrin; Debonsi, Hosana Maria; Lopes, Norberto Peporine; Marcos, Ricard; de Oliveira, Danielle Palma
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 2054-2063
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Azo dyes constitute the largest class of synthetic dyes. Following oral exposure, these dyes can be reduced to aromatic amines by the intestinal microflora or liver enzymes. This work identified the products formed after oxidation and reduction of the dye Disperse Red 1, simulating hepatic biotransformation and evaluated the mutagenic potential of the resultant solution. Controlled potential electrolysis was carried out on dye solution using a Potentiostat/Galvanostat. HPLC-DAD and GC/MS were used to determine the products generated after the oxidation/reduction process. The Salmonella/microsome assay with the strains TA98 and YG1041 without 59, and the mouse lymphoma assay (MLA) using the thymidine kinase (Tk) gene, were used to evaluate the mutagenicity of the products formed. Sulfate 2-[(4-aminophenyl)ethylaminol-ethanol monohydrate, nitrobenzene, 4-nitro-benzamine and 2-(ethylphenylamino)-ethanol were detected. This dye has already being assigned as mutagenic in different cell system. In addition, after the oxidation/reduction process the dye still had mutagenic activity for the Salmonella/microsome assay. Nevertheless...

Cathodic stripping voltammetric detection and determination at a hanging mercury-drop electrode of dye contaminants in purified biomaterials: study of the human serum albumin and reactive dye 120 system

Guaratini, CCI; Zanoni, Maria Valnice Boldrin; Fogg, A. G.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 65-72
ENG
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Procion red HE-3B (RR120) is an example of dye currently used in affinity purification. A method is described for determining trace amounts of RR120 dye contaminant in human serum albumin by cathodic stripping voltammetry. The method is based on a measure of a well-defined peak at -0.58 V, obtained when samples of HSA protein (0.01-2% w/v) containing dye concentrations are submitted to a heating time of 330 min at 80degreesC in NaOH, pH 12.0 and the samples are removed to a solution containing Britton-Robinson buffer, pH 4.0. Using an optimum accumulation potential and tune of 0 V and 240 s, respectively, linear calibration curves were obtained from 1.0 X 10(-9) to 1.0 X 10(-8) mol 1(-1) for RR120 dye. Leakage/hydrolysis of reactive red 120 from an agarose support (e.g. at pH 2 or 12) can also be conveniently determined at very low levels (sub-mug ml(-1)) by means of cathodic stripping voltammetry, which involves adsorptive accumulation of the dye onto the hanging mercury-drop electrode. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Evaluation of color removal and degradation of a reactive textile azo dye on nanoporous TiO2 thin-film electrodes

Carneiro, P. A.; Osugi, M. E.; Sene, J. J.; Anderson, M. A.; Zanoni, Maria Valnice Boldrin
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 3807-3820
ENG
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The feasibility of the photobleaching of a textile azo dye, reactive orange 16 (C.I. 17757), in aqueous solution using titanium dioxide thin-film electrodes prepared by the sol-gel method was investigated. The best conditions for maximum photoelectrocatalytic degradation were found to be pH > 10 for Na2SO4 medium and pH < 6 for NaCl. In both situations, an applied potential of +1.0 V and low dye concentration are recommended, when 100% of color removal is obtained after 20 min of photoelectrocatalysis. The effects of side reaction pathway on the degradation rate of dye in sulfate and chloride medium were presented and the best performance are optimized to situations closed to that verified in the textile effluent. The influence of variables as applied potential, pH, supporting electrolyte and dye concentration on the kinetics of photoelectrochemical degradation also were investigated. Oxalic acid is identified by HPLC and UV-Vis spectrophotometric methods as the main degradation product generated after 180 min of photoelectrocatalysis of 4 x 10(-5) mol l(-1) dye in sodium sulphate pH 12 and NaCl pH 4.0 and a maximum reduction of 56 and 62% TOC was obtained, respectively. (C) 2004 Elsevier Ltd. All rights reserved.

Electrochemical oxidation of an acid dye by active chlorine generated using Ti/Sn(1-x)Ir O-x(2) electrodes

Oliveira, Flavio H.; Osugi, Marly E.; Paschoal, Fabiana M. M.; Profeti, Demetrius; Olivi, Paulo; Zanoni, Maria Valnice Boldrin
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 583-592
ENG
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The generation of active chlorine on Ti/Sn(1-x)Ir (x) O-2 anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of chloride ions (0.05 mol L-1) and a low current density (5 mA cm(-2)) it was possible to produce up to 60 mg L-1 of active chlorine on a Ti/Sn0.99Ir0.01O2 anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated with in situ electrogenerated active chlorine on Ti/Sn(1-x)Ir (x) O-2 anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4, 25 mA cm(-2) and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus time reveal a zero order reaction at dye concentrations up to 1.0 x 10(-4) mol L-1. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed.

Chlorine disinfection of dye wastewater: Implications for a commercial azo dye mixture

Vacchi, Francine Inforçato; Albuquerque, Anjaina Fernandes; Vendemiatti, Josiane Aparecida; Morales, Daniel Alexandre; Ormond, Alexandra B.; Freeman, Harold S.; Zocolo, Guilherme Julião; Zanoni, Maria Valnice Boldrin; Umbuzeiro, Gisela
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 302-309
ENG
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Azo dyes, the most widely used family of synthetic dyes, are often employed as colorants in areas such as textiles, plastics, foods/drugs/cosmetics, and electronics. Following their use in industrial applications, azo dyes have been found in effluents and various receiving waters. Chemical treatment of effluents containing azo dyes includes disinfection using chlorine, which can generate compounds of varying eco/genotoxicity. Among the widely known commercial azo dyes for synthetic fibers is C.I. Disperse Red 1. While this dye is known to exist as a complex mixture, reports of eco/genotoxicity involve the purified form. Bearing in mind the potential for adverse synergistic effects arising from exposures to chemical mixtures, the aim of the present study was to characterize the components of commercial Disperse Red 1 and its chlorine-mediated decoloration products and to evaluate their ecotoxicity and mutagenicity. In conducting the present study, Disperse Red 1 was treated with chlorine gas, and the solution obtained was analyzed with the aid of LC-ESI-MS/MS to identify the components present, and then evaluated for ecotoxicity and mutagenicity, using Daphnia similis and Salmonella/microsome assays, respectively. The results of this study indicated that chlorination of Disperse Red 1 produced four chlorinated aromatic compounds as the main products and that the degradation products were more ecotoxic than the parent dye. These results suggest that a disinfection process using chlorine should be avoided for effluents containing hydrophobic azo dyes such commercial Disperse Red 1. © 2012 Elsevier B.V..

Application of zeolite-Arthrobacter viscosus system for the removal of heavy metal and dye : chromium and azure B

Rosales, E.; Pazos, M.; Sanromán, M. A.; Tavares, M. T.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
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A hybrid system combining the ion-exchange properties of a NaY zeolite and the characteristics of the bacterium Arthrobacter viscosus was investigated to treat polluted effluents with dye and toxic metals. In this study, the dye and the metal ion employed were a thiazine dye, Azure B, and chromium (VI), respectively. Initially, the removal of dye by the zeolite was tested. The analysis of dye equilibrium isotherms data was done using Langmuir, Freundlich, Sips and Redlich–Peterson models. Redlich–Peterson model gave the better fitting to data. In the dye adsorption studies, pseudo-second order kinetics showed the more reliable results. Operating at the optimised conditions in the treatment of single pollutants, a mixture of dye and metal solutions was treated reaching a removal higher than 50% for chromium (VI) and higher than 99% for dye, in 8 days.

Dye-sensitized solar cells: a successful combination of materials

Longo,Claudia; De Paoli,Marco-A.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 EN
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Dye-sensitized TiO2 solar cells, DSSC, are a promising alternative for the development of a new generation of photovoltaic devices. DSSC are a successful combination of materials, consisting of a transparent electrode coated with a dye-sensitized mesoporous film of nanocrystalline particles of TiO2, an electrolyte containing a suitable redox-couple and a Pt coated counter-electrode. In general, Ru bipyridyl complexes are used as the dye sensitizers. The light-to-energy conversion performance of the cell depends on the relative energy levels of the semiconductor and dye and on the kinetics of the electron-transfer processes at the sensitized semiconductor | electrolyte interface. The rate of these processes depends on the properties of its components. This contribution presents a discussion on the influence of each of the materials which constitute the DSSC of the overall process for energy conversion. An overview of the results obtained for solid-state dye-sensitized TiO2 solar cells assembled with polymer electrolytes is also presented.

Local delivery of fluorescent dye for fiber-optics confocal microscopy of the living heart

Huang, Chao; Kaza, Aditya K.; Hitchcock, Robert W.; Sachse, Frank B.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
EN_US
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Fiber-optics confocal microscopy (FCM) is an emerging imaging technology with various applications in basic research and clinical diagnosis. FCM allows for real-time in situ microscopy of tissue at sub-cellular scale. Recently FCM has been investigated for cardiac imaging, in particular, for discrimination of cardiac tissue during pediatric open-heart surgery. FCM relies on fluorescent dyes. The current clinical approach of dye delivery is based on systemic injection, which is associated with high dye consumption, and adverse clinical events. In this study, we investigated approaches for local dye delivery during FCM imaging based on dye carriers attached to the imaging probe. Using three-dimensional confocal microscopy, automated bench tests, and FCM imaging we quantitatively characterized dye release of carriers composed of open-pore foam only and foam loaded with agarose hydrogel. In addition, we compared local dye delivery with a model of systemic dye delivery in the isolated perfused rodent heart. We measured the signal-to-noise ratio (SNR) of images acquired in various regions of the heart. Our evaluations showed that foam-agarose dye carriers exhibited a prolonged dye release vs. foam-only carriers. Foam-agarose dye carriers allowed reliable imaging of 5–9 lines...

Dye decolourization by immobilized laccase and impact of auxiliary chemicals on dye decolourization

Champagne, Paul-Philippe
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 1382542 bytes; application/pdf
EN; EN
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Textile dyes are molecules designed to impart a permanent colour to textile fabrics. They pose an environmental problem because they are toxic and they decrease the aesthetic value of rivers and lakes. Current technologies for dye removal cannot remove all classes of dyes and two or more technologies are usually combined to achieve statisfactory decolourization efficiencies. Lignin-degrading enzymes like laccases are potential technologies for dye decolourization and decolourization with immobilized laccase has been intensively investigated. The majority of those studies however have focused on dye disappearance and several reported that significant dye adsorption had occured during the dye removal, making the role of the enzyme unclear. Moreover, textile wastewaters contain auxiliary chemicals that can impact enzymatic dye decolourization and very few studies have evaluated the impact of those substances on laccase. This research evaluated the feasibility of treating dye-contaminated textile wastewaters with an immobilized laccase system. The first sub-objective was to examined the decolourization of Reactive blue 19 (an anthraquinone dye) by Trametes versicolor laccase immobilized on controlled porosity carrier (CPC) silica beads and the second was to analyze the kinetic effects of a non-ionic surfactant Merpol...

Chitosan/acid dye interactions in wool dyeing system

Jocic, Dragan; Vílchez, Susana; Topalovic, Tatjana; Navarro, Antonio; Jovancic, Petar; Julià, María Rosa; Erra Serrabasa, Pilar
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
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9 pages, 4 figures, 3 tables.-- Available online Dec 18, 2004.; This study assesses the interactions that could occur during dyeing of the chitosan treated wool fibres on basis of the spectrophotometric study, by measuring the absorbance values of the solutions containing dye and chitosan. It has been shown that there is a 1:1 stoichiometry between protonated amino groups and sulfonate acid groups on the dye ions in low concentrated chitosan solutions. This interaction forms an insoluble chitosan/dye product. With the excess of chitosan in the solution, the dye can be distributed between the different chitosan molecules and the soluble chitosan/dye products remain in the solution. The mechanism of the interaction is suggested, that involves the possibility of adsorbed dye molecules to be desorbed and redistributed between other components present in the system, depending on system parameters (pH, temperature and electrolyte presence). This fact is important in explanation of dyeing behaviour of chitosan treated wool and enables the assessment of the mechanism of dyeing of accordingly modified textile fibres.; Peer reviewed

Preferred Molecular Orientation of Coumarin 343 on TiO2 Surfaces: Application to Dye-Sensitized Solar Cells

McCree-Grey, Jonathan; Cole, Jacqueline Manina; Evans, Peter
Fonte: ACS Publicador: ACS
Tipo: Article; accepted version
EN
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This is the author accepted manuscript. The final version is available from ACS via http://dx.doi.org/10.1021/acsami.5b03572; The dye?TiO2 interfacial structure in working electrodes of dye-sensitized solar cells (DSCs) is known to influence its photovoltaic device performance. Despite this, direct and quantitative reports of such structure remain sparse. This case study presents the application of X-ray reflectometry to determine the preferred structural orientation and molecular packing of the organic dye, coumarin 343, adsorbed onto amorphous TiO2. Results show that the dye molecules are, on average, tilted by 61.1? relative to the TiO2 surface, and are separated from each other by 8.2 ?. These findings emulate the molecular packing arrangement of a monolayer of coumarin 343 within its crystal structure. This suggests that the dye adsorbs onto TiO2 in one of its lowest energy configurations, i.e. dye?TiO2 self assembly is driven more by thermodynamic rather than kinetic means. Complementary DSC device tests illustrate that this interfacial structure compromises photovoltaic performance, unless a suitably sized co-adsorbant is interdispersed between the coumarin 343 chromophores on the TiO2 surface.; J. M.-G. acknowledges ANSTO for a part-funded PhD studentship. J. M. C. is grateful to the 1851 Royal Commission for the 2014 Design Fellowship...

Dye desensitization studies: AgBr core-shell emulsions

Zheng, J.; DiFrancesco, A. Gary; Hailstone, Richard; Callant, Paul; DeKeyzer, Rene
Fonte: Maney Publishing on behalf of the Royal Photographic Society Publicador: Maney Publishing on behalf of the Royal Photographic Society
Tipo: Abstract
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A matched pair of 0.73 μm AgBr core-shell octahedral emulsions, sulfur-plus-gold sensitized either internally or on the surface, was used to study dye desensitization by J-aggregating dyes. Six dyes having a systematically varying electrochemical oxidation potential, E[ox], were studied at 20, 40, 60, 80 and 100 per cent monolayer coverage. Except for one of the dyes, there was no desensitization of the internal image. However, several dyes showed desensitization of the surface image, which increased with increasing dye coverage, and which in some cases prevented the measurement of dye desensitization at monolayer coverage (> 2 log E speed loss). Dye desensitization occurred at a threshold dye E[ox] of about 1.1 V (versus Ag/AgCl in acetonitrile) and increased dramatically at lower E[ox]. Desensitization was about the same or greater at low irradiance as compared with high-irradiance results, and the development time had little, if any, impact on desensitization. It is argued that these results support a desensitization mechanism for these dyes that involves photohole processes and not dye-induced dispersity of the latent image. The photohole processes involve oxidized dye either as a recombination centre for electrons or in the direct oxidation of the latent image or latent subimage. The absence of internal image desensitization suggests that the latter process is the dominant desensitization mechanism (Refer to PDF for exact formulas).

Chemical sensitization of tabular-grain emulsions in the presence of sensitizing dye

Yang, Weide Victor
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
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This thesis considers the role a spectral sensitizing dye plays in chemical sensitization for tabular-grain emulsions. Different approaches for introducing sensitizing dye have been chosen in conjunction with sulfur-thiocyanate-gold (S-SCNAu) chemical sensitization, 1. At the completion of nucleation (NUC) 2. At various precipitation completion points (pcp) a. At 35% pcp b. At 70% pcp c. At 80% pcp d. At 90% pcp e. At 100% pcp (i.e., at the beginning of Ostwald ripening) 3. Before chemical sensitization with varied digest addition sequences: Dye-SSCN- Au, Dye-SCN-S-Au 4. Conventionally: S-SCN-Au-Dye, i.e., dye introduced after chemical sensitization (control). It also considers what happens for dye addition at various pcp to grain morphologies via electron microscopy study, to grain size distribution via turbidity measurement, to dye absorption via spectrogram investigation, and to the efficiency of chemical sensitization. Pure silver bromide emulsions were prepared with a linear ramp flow program through a computerized system with pAg control. The conditions for digest giving the best sensitometric performance were determined.

Electrochemical Degradation and Cyclic Voltammetric Studies of Textile Reactive Azo Dye Cibacron Navy WB

Kariyajjanavar,P.; Narayana,J.; Nayaka,Y. A.; Umanaik,M.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
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The removal of pollutants from effluents by electrochemical degradation has become an attractive method in recent years. This paper deals with the removal of reactive textile dye Cibacron Navy W-B (CNWB) from an aqueous medium by the electrochemical method using graphite carbon electrodes. Electrochemical behavior of reactive azo dye CNWB was performed with cyclic voltammetry in sulphuric acid medium using glassy carbon as working electrode. The potential range selected for the dye was in the range +700 mV to -450 mV. The voltammetric curve of CNWB shows cathodic peaks at +50 mV, -155 mV and -317 mV and anodic peaks at +382 mV and +547 mV, respectively. The decolourisation efficiency was assessed through UV-Visible studies. The LC-MS of the dye were analyzed before and after electrochemical treatment and confirmed that the azo groups and aromatic rings were destroyed. The effect of pH and nature of supporting electrolytes on the electrochemical degradation of dye was also studied. The maximum Chemical Oxygen Demand (COD) removal efficiency was ~100% for the dye solutions at 5 gL-1 of NaCl concentration. The results revealed the suitability of the present process for the effective degradation of dye effluents.