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Polypyrrole/copper hexacyanoferrate hybrid as redox mediator for glucose biosensors

Fiorito, Pablo A.; Brett, Christopher M.A.; Córdoba de Torresi, Susana I.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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A copper containing Prussian Blue analogue was incorporated into a conducting polypyrrole film. The modified electrode was synthesized through an electrochemical two-step methodology leading to very stable and homogeneous hybrid films. These electrodes were proved to show excellent catalytic properties towards H2O2 detection, with a performance higher than those observed for Prussian Blue and other analogues. Electrochemical impedance spectroscopy experiments demonstrated that the excellent performance of these hybrid films is strongly related to the electronic conductivity of the polymeric matrix that is wiring the copper hexacyanoferrate sites. A glucose biosensor was built-up by the immobilization of glucose oxidase; the sensitivity obtained being higher than other biosensors reported in the literature even in Na+ containing electrolytes.; http://www.sciencedirect.com/science/article/B6THP-4HJRRM7-3/1/add5c8a178dcbf252ce544cd9152452e

Carbon film electrodes for oxidase-based enzyme sensors in food analysis

Luca, S. De; Florescu, M.; Ghica, M. E.; Lupu, A.; Palleschi, G.; Brett, C. M. A.; Compagnone, D.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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Carbon film resistor electrodes have been evaluated as transducers for the development of multiple oxidase-based enzyme electrode biosensors. The resistor electrodes were first modified with Prussian Blue (PB) and then covered by a layer of covalently immobilized enzyme. Electrochemical impedance spectroscopy was used to characterize the interfacial behaviour of the Prussian Blue modified and enzyme electrodes; the spectra demonstrated that the access of the substrates is essentially unaltered by application of the enzyme layer. These enzyme electrodes were used to detect the substrate of the oxidase (glucose, ethanol, lactate, glutamate) via reduction of hydrogen peroxide at +50 mV versus Ag/AgCl in the low micromolar range. Response times were 1-2 min. Finally, the glucose, ethanol and lactate electrochemical biosensors were used to analyse complex food matrices--must, wine and yoghurt. Data obtained by the single standard addition method were compared with a spectrophotometric reference method and showed good correlation, indicating that the electrodes are suitable for food analysis.; http://www.sciencedirect.com/science/article/B6THP-4GNTFGP-2/1/087dc22044a84cfb2a1badf317934bca

On the template synthesis of nanostructured inorganic/organic hybrid films

GONCALES, V. R.; SALVADOR, R. P.; ALCANTARA, M. R.; TORRESI, S. I. Cordoba de
Fonte: ELECTROCHEMICAL SOC INC Publicador: ELECTROCHEMICAL SOC INC
Tipo: Artigo de Revista Científica
ENG
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Prussian Blue has been introduced as a mediator to achieve stable, sensitive, reproducible, and interference-free biosensors. However, Na(+), Li(+), H(+), and all group II cations are capable to block the activity of Prussian Blue and, because Na(+) can be found in most human fluids, Prussian Blue analogs have already been developed to overcome this problem. These analogs, such as copper hexacyanoferrate, have also been introduced in a conducting polypyrrole matrix to create hybrid materials (copper hexacyanoferrate/polypyrrole, CuHCNFe/Ppy) with improved mechanical and electrochemical characteristics. Nowadays, the challenges in amperometric enzymatic biosensors consist of improving the enzyme immobilization and in making the chemical signal transduction more efficient. The incorporation of nanostructured materials in biosensors can optimize both steps and a nanostructured hybrid CuHCNFe/Ppy mediator has been developed using a template of colloidal polystyrene particles. The nanostructured material has achieved sensitivities 7.6 times higher than the bulk film during H(2)O(2) detection and it has also presented better results in other analytical parameters such as time response and detection limit. Besides, the nanostructured mediator was successfully applied at glucose biosensing in electrolytes containing Prussian Blue blocking cations. (C) 2008 The Electrochemical Society.

Structure effects of self-assembled Prussian blue confined in highly organized mesoporous TiO(2) on the electrocatalytic properties towards H(2)O(2) detection

GAITAN, Martin; GONCALES, Vinicius R.; SOLER-ILLIA, Galo J. A. A.; BARALD, Luis M.; TORRESI, Susana I. Cordoba de
Fonte: ELSEVIER ADVANCED TECHNOLOGY Publicador: ELSEVIER ADVANCED TECHNOLOGY
Tipo: Artigo de Revista Científica
ENG
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Here we report the derivatization of mesoporous TiO(2) thin films for the preparation of H(2)O(2) amperometric sensors. The coordination of the bifunctional ligand 1,10 phenantroline, 5,6 dione on the surface Ti(IV) ions provides open coordination sites for Fe(II) cations which are the starting point for the growth of a layer of Prussian blue polymer. The porous structure of the mesoporous TiO(2) allows the growth, ion by ion of the coordination polymer. Up to four layer of Prussian blue can be deposit without losing the porous structure of the film, which results in an enhanced response of these materials as H(2)O(2) sensors. These porous confined PB modified electrodes are robust sensors that exhibit good reproducibility, environmental stability and high sensitivity towards H(2)O(2) detection. (C) 2010 Elsevier B.V. All rights reserved.; Universidad de Buenos Aires UBACyT, Argentina; Universidad de Buenos Aires UBACyT, Argentina; ANPCyT; ANPCyT[PICT 2004-25409]; ANPCyT[2005-34518]; ANPCyT; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fabrication of disposable voltammetric electronic tongues by using Prussian Blue films electrodeposited onto CD-R gold surfaces and recognition of milk adulteration

PAIXAO, Thiago R. L. C.; BERTOTTI, Mauro
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
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A new approach to fabricate a disposable electronic tongue is reported. The fabrication of the disposable sensor aimed the integration of all electrodes necessary for measurement in the same device. The disposable device was constructed with gold CD-R and copper sheets substrates and the sensing elements were gold, copper and a gold surface modified with a layer of Prussian Blue. The relative standard deviation for signals obtained from 20 different disposable gold and 10 different disposable copper electrodes was below 3.5%. The performance, electrode materials and the capability of the device to differentiate samples were evaluated for taste substances model, milk with different pasteurization processes (homogenized/pasteurized, ultra high temperature (UHT) pasteurized and UHT pasteurized with low fat content) and adulterated with hydrogen peroxide. In all analysed cases, a good separation between different samples was noticed in the score plots obtained from the principal component analysis (PCA). Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo); CNPq (Conselho Nacional de Desenvolvirnento Cientifico e Tecnologico); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Filmes de azul da Prússia sobre ITO: estudos de pós-tratamento e estabilidade frente diferentes pHs e diferentes compostos fosfatados; Films of Prussian blue on ITO: studies of post-treatment and stability in differents pHs and differents phosphate compounds

Reis, Rafael Machado
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 14/10/2008 PT
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Nesta dissertação estudou-se a influência dos parâmetros de pós-tratamento eletroquímico, em condições potenciodinâmicas, sobre a estabilidade e reatividade frente à organofosfatos do filme eletrodepositado de hexacianoferrato (II) de ferro (III), mais conhecido como azul da Prússia (PB). O pós-tratamento do filme em baixas velocidades de varredura leva à formação do PB "solúvel" com a formação de grãos maiores e um filme mais estável eletroquimicamente como demonstrado por ensaios de voltametria cíclica (VC), microscopia de força atômica (AFM) e espectroscopia de fotoelétrons excitados por raios X (XPS). Filmes pós-tratados em meio HCl/KCl 0,1M foram mais eletroquimicamente estáveis em meio ácido, enquanto filmes submetidos à pós-tratamento em meio neutro foram mais estáveis em meio neutro.; In this work it was studied the influence of the electrochemical posttreatment parameters in potenciodinamics conditions on the stability and reactivity against organophosphates by eletrodepositaded iron (III) hexacyanoferrate (II), better known as blue of Prussia (PB). The posttreatment of the film at low sweep rates leads to the formation of the PB "soluble" with the formation of larger grains and a more electrochemically stable films as demonstrated by cyclic voltammetry (VC)...

Estudo eletroquímico de micropartículas individuais e colisões de nanopartículas de magnetita modificadas com azul da Prússia; Electrochemical Study of Individual Microparticles and Collisions of Nanoparticles of Magnetite Modified with Prussian Blue

Santos, Germano Pereira dos
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 05/02/2015 PT
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De acordo com a literatura recente, a eletroquímica de partículas magnéticas e fenômenos de colisões em superfícies eletródicas resultam em curvas voltamétricas e amperométricas com perfis completamente destoados do convencional. Alguns modelos teóricos propõem explicações, no entanto, ainda se observa a necessidade de aquisição de mais dados experimentais. Visando contribuir com esta área, esta Dissertação de Mestrado aborda a manipulação de micropartículas e nanopartículas de magnetita modificadas com azul da Prússia (Fe3O4-PB), bem como o estudo das propriedades eletroquímicas das partículas na presença de um campo magnético externo. Filmes constituídos por micropartículas sobre eletrodos de carbono (grafite) foram obtidos por duas técnicas distintas, drop coating e magneto-deposição. Para ambos os métodos, os filmes apresentaram dois picos nos voltamogramas, um de oxidação (0,12 V) e outro de redução (-0,05 V), que estão associados ao par redox azul da Prússia/branco da Prússia. Para o filme obtido via drop coating, observaram-se correntes de pico mais elevadas. Também, micropartículas de Fe3O4-PB individuais foram isoladas (single particle) com auxílio de um microscópio óptico e analisadas por voltametria...

Evaluation of glucose biosensors based on Prussian Blue and lyophilised, crystalline and cross-linked glucose oxidases (CLEC (R))

de Mattos, I. L.; Lukachova, L. V.; Gorton, L.; Laurell, T.; Karyakin, A. A.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 963-974
ENG
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Glucose biosensors based on lyophilised, crystalline and cross-linked glucose oxidase (GOx, CLEC(R)) and commercially available lyophilised GOx immobilised on top of glassy carbon electrodes modified with electrodeposited Prussian Blue are critically compared. Two procedures were carried out for preparing the biosensors: (1) deposition of one layer of adsorbed GOx dissolved in an aqueous solution followed by deposition of two layers of low molecular weight Nafion(R) dissolved in 90% ethanol, and (2) deposition of two layers of a mixture of GOx with Nafion dissolved in 90% ethanol. The performance of the biosensors was evaluated in terms of linear response range for hydrogen peroxide and glucose, detection limit, and susceptibility to some common interfering species (ascorbic acid, acetaminophen and uric acid). The operational stability of the biosensors was evaluated by applying a steady potential of -50 mV versus Ag/AgCl to the glucose biosensor and injecting standard solutions of hydrogen peroxide and glucose (50 muM and 1.0 mM, respectively, in phosphate buffer) for at least 5 h in a flow-injection system. Scanning electron microscopy was used for visualisation of the Prussian Blue redox catalyst and in the presence of the different GOx preparations on the electrode surface. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Evaluation of glucose biosensors based on Prussian Blue and lyophilised, crystalline and cross-linked glucose oxidases (CLEC®)

De Mattos, Ivanildo Luiz; Lukachova, Lilia V.; Gorton, Lo; Laurell, Thomas; Karyakin, Arkady A.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 963-974
ENG
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Glucose biosensors based on lyophilised, crystalline and cross-linked glucose oxidase (GOx, CLEC®) and commercially available lyophilised GOx immobilised on top of glassy carbon electrodes modified with electrode-posited Prussian Blue are critically compared. Two procedures were carried out for preparing the biosensors: (1) deposition of one layer of adsorbed GOx dissolved in an aqueous solution followed by deposition of two layers of low molecular weight Nafion® dissolved in 90% ethanol, and (2) deposition of two layers of a mixture of GOx with Nafion dissolved in 90% ethanol. The performance of the biosensors was evaluated in terms of linear response range for hydrogen peroxide and glucose, detection limit, and susceptibility to some common interfering species (ascorbic acid, acetaminophen and uric acid). The operational stability of the biosensors was evaluated by applying a steady potential of - 50 mV versus Ag/AgCl to the glucose biosensor and injecting standard solutions of hydrogen peroxide and glucose (50 μM and 1.0 mM, respectively, in phosphate buffer) for at least 5 h in a flow-injection system. Scanning electron microscopy was used for visualisation of the Prussian Blue redox catalyst and in the presence of the different GOx preparations on the electrode surface. © 2001 Elsevier Science B.V.

Flow injection amperometric determination of persulfate in cosmetic products using a Prussian Blue film-modified electrode

De Oliveira, Marcelo F.; Saczk, Adelir A.; Neto, Jose A. Gomes; Roldan, Paulo S.; Stradiotto, Nelson R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 371-380
ENG
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A flow-injection system with a glassy carbon disk electrode modified with Prussian Blue film is proposed for the determination of persulfate in commercial samples of hair bleaching boosters by amperometry. The detection was obtained by chronoamperometric technique and the sample is injected into the electrochemical cell in a wall jet configuration. Potassium chloride at concentration of 0.1 mol L-1 acted as sample carrier at a flow rate of 4.0 mL min-1 and supporting-electrolyte. For 0.025 V (vs. Ag/AgCl) applied voltage, the proposed system handles ca. 160 samples per hour (1.0 10-4 - 1.0 10-3 mol L-1 of persulfate), consuming about 200 μL sample and 11 mg KCl per determination. Typical linear correlations between electrocatalytic current and persulfate concentration was ca. 0.9998. The detection limit is 9.0 10-5 mol L-1 and the calculated amperometric sensibility 3.6 103 μA L mol -1. Relative standard deviation (n =12) of a 1.0 10-4 mol L-1 sample is about 2.2%. The method was applied to persulfate determination in commercial hair-bleaching samples and results are in agreement with those obtained by titrimetry at 95% confidence level and good recoveries (95 - 112%) of spiked samples were found. © 2003 by MDPI.

Obtenção fotoquímica de nanocompósito baseado em azul da Prússia e óxido de grafeno reduzido; Photochemical obtention of nanocomposite based on Prussian blue and reduced grephene oxide

Pãmyla Layene dos Santos
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/02/2015 PT
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O azul da Prússia (AP) é um dos mais antigos compostos de coordenação e pode ser utilizado na modificação de sensores eletroquímicos para a detecção de H2O2, o AP pode catalisar a redução do peróxido e por isso é conhecido como "artificial peroxidase". Entretanto, filmes de AP não apresentam boa estabilidade eletroquímica e alternativas como a obtenção de nanocompósito baseados em AP e grafeno podem ser utilizadas para contornar o problema. O grafeno é um material com alta condutividade, flexibilidade e resistência à tração, pode ser obtido pelo método de Hummers que consiste na redução do óxido de grafeno e neste caso é chamado de óxido de grafeno reduzido. Assim, o objetivo deste trabalho é a obtenção fotoquímica de um nanocompósito baseado em azul da Prússia (AP) e óxido de grafeno reduzido (rGO) que permite uma combinação das propriedades eletrocatalíticas do AP e condutoras do rGO para a aplicação em sensores eletroquímicos. Além disso, espera-se uma maior estabilidade eletroquímica deste material. Os materiais óxido de grafeno reduzido e azul da Prússia foram obtidos separadamente pelos métodos químicos e fotoquímicos com a utilização de LEDs. Os resultados mostraram vantagens do método fotoquímico como o controle da morfologia e do tamanho dos cristais de azul da Prússia. O grau de redução dos materiais baseados em grafeno foi controlado com o tempo de irradiação no LED e isso foi refletido em suas propriedades eletroquímicas...

SÍNTESE E CARACTERIZAÇÃO DE COMPÓSITOS ORGÂNICO-INORGÂNICOS MACROPOROSOS PARA O SENSORIAMENTO DE H2O2

Santos,Juliana L.; Gonçales,Vinicius R.; Cintra,Elaine P.; Torresi,Susana I. Córdoba de
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 PT
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Electrodes modified with poly(5-amino-1-naphthol)/Prussian blue (poly(5-NH2-1-NAP)/PB) hybrid films are able to electrochemically reduce H2O2 in medium containing an excess of Na+ cations. This is an important advantage for biosensing applications over electrodes in which only conventionally (electro) deposited Prussian blue is present. Consequently, the aim of this work was to examine the application of templates of ordered arrays of colloidal poly(styrene) spheres (800, 450 and 100 nm in diameter) to produce inverse opal structures of poly(5-NH2-1-NAP)/PB hybrid platforms, in an effort to study the influence of the increase in surface area/volume ratio and higher exposition of the mediator active sites on material performance during H2O2 determination employing the different sized porous structures. Moreover, since the accentuated hydrophilic character of poly(5-NH2-1-NAP)/PB also allows H2O2 electrochemical reduction in inner active sites, issues concerning the amount of mediator electrodeposited on the electrode were also reflected in the observed results.

Rhodium-Prussian Blue modified carbon paste electrode (Rh-PBMCPE) for amperometric detection of hydrogen peroxide

Ivama,Viviane Midori; Serrano,Silvia H. P.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2003 EN
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Prussian Blue was deposited at carbon paste electrode surface from a solution containing 2.0 x 10-3 mol L-1 K3[Fe(CN)6], 3.0 x 10-3 mol L-1 FeCl3 and 1.0 x 10-2 mol L-1 HCl using two controlled potentials. To improve the stability of the modified electrode it was 50 times cycled in a solution containing 1.0 x 10-3 mol L-1 RhCl3, 0.50 mol L-1 KCl and 0.010 mol L-1 HCl in the potential range from - 0.40 V to 0.60 V at 60 mV s-1. The Rh - Prussian Blue carbon paste modified electrode (Rh-PBMCPE) showed good stability during amperometric catalytic determination of H2O2 at 0.040 V, without ascorbic and uric acids interferences. The current changed linearly with H2O2 concentrations in the range of 5.0 x 10-5 - 8.6 x 10-4 mol L-1. The estimated detection limit was 2.8 x 10-5 mol L-1 with sensibility changing from 1.32 to 0.96 A mol-1 L cm-2 along five days (180 determinations).

Selective Determination of Unsymmetrical Dimethylhydrazine on a Prussian Blue Modified Carbon Paste Electrode

Sobhanmanesh,Bagher; Najafi,Mostafa
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 EN
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The electrocatalytic oxidation of unsymmetrical dimethylhydrazine (UDMH) has been studied on a Prussian Blue modified carbon paste electrode (PBMCPE) by cyclic voltammetry technique. The results show that Prussian Blue acts as a suitable modifier for electron transfer in the oxidation of UDMH. A linear range of 3 × 10-5 to 1.15 × 10-3 mol L-1, with a limit of detection (3σ) of 1.6 × 10-5 mol L-1 was obtained using the amperometric method. The proposed sensor exhibited several advantages, including, namely, no interference from hydrazine, simple preparation, good stability and repeatability. Finally, the PBMCPE was successfully applied for determination of UDMH in water samples.

Caracterizações e aplicações analíticas de eletrodos compósitos modificados com Azul da Prússia e determinações simultâneas em sistemas de análise por injeção em batelada empregando somente um eletrodo de trabalho

Silva, Rodrigo Amorim Bezerra da
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Tese de Doutorado
POR
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Esta tese apresenta algumas potencialidades dos sistemas de análise por injeção em fluxo (FIA) e análise por injeção em batelada (BIA) acopladas à detecção amperométrica para o desenvolvimento de métodos de rotina úteis em alguns setores industriais, como o alimentício, farmacêutico e de biocombustíveis. Nesta perspectiva, foi empregado um eletrodo compósito modificado com azul da Prússia na determinação de peróxido de hidrogênio em leite e antisséptico bucal. Além disso, um eletrodo de diamante dopado com boro (BDD) foi usado em determinações simultâneas de fármacos presentes na mesma formulação farmacêutica (paracetamol e cafeína; dipirona e cafeína) e de três antioxidantes adicionados em biodiesel: terc-butilhidroquinona (TBHQ), butilhidroxianisol (BHA) e butilhidroxitolueno (BHT). O eletrodo compósito modificado com azul da Prússia foi construído a partir de um compósito fluído preparado em laboratório (grafite / adesivo epóxi / ciclohexanona / partículas de azul da Prússia). Os melhores resultados foram obtidos quando o grafite modificado com azul da Prússia foi adicionado no compósito fluido em proporções de até 30 % (m/m). Este compósito modificado foi inserido em dois distintos materiais suporte: (1) ponteira de micropipeta (Ø = 1...

Microbial dissimilatory iron(III) reduction: Studies on the mechanism and on processes of environmental relevance; Mikrobielle dissimilatorische Eisen(III)-Reduktion: Untersuchungen des Mechanismus und verschiedener umweltrelevanter Prozesse

Jahn, Michael
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
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Many microbes are able to respire aerobically oxygen or anaerobically other electron acceptors for example sulphate, nitrate, manganese(IV) or Fe(III). As iron minerals are widespread in nature, dissimilatory iron(III) reduction by different microorganisms is a very important process of anaerobic respiration. The general goal of this work was to improve the knowledge of processes, in which iron-reducing microbes are said to play an important role. For this purpose, in one part the focus was made on anaerobic contaminant degradation and in the other part on studies on the mechanism of microbial iron(III) reduction. Both parts were investigated in growth and cell suspension experiments with different microorganisms. At former industrial sites, monoaromatic hydrocarbons, such as benzene, toluene, ethylbenzene, and xylene (BTEX), are widespread contaminants, which cause different problems due to their high solubility in water and strong toxicity. At such sites, where usually anoxic conditions prevail, the anaerobic degradation of these compounds is a very important process. In this study, the anaerobic degradation of BTEX compounds by dissimilatory iron-reducing microorganisms was examined. In order to isolate new bacterial strains, enrichment cultures with the different BTEX compounds added as sole carbon and energy source were prepared. Successful enrichment cultures were obtained for all BTEX substrates both in the presence and absence of AQDS (9...

Estratégia de modificação de eletrodos com filmes de azul da Prússia a partir de complexo pentacianoferrato; Strategy for electrode modification with Prussian blue films using pentacyanoferrate complexes

Bruno Morandi Pires
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/08/2014 PT
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Complexos de cianoferratos receberam destaque na década de 70, com a investigação de suas estruturas eletrônicas e reatividade. Estas espécies possuem grande afinidade por compostos N-heterocíclicos, aminoácidos, sulfóxidos, tio éteres e tioamidas. A modificação com diferentes ligantes permite a modulação suas propriedade e reatividade. Esses complexos também podem produzir o azul da Prússia, que é um mimético da enzima peroxidase. Neste trabalho, foi sintetizado o complexo de pentacianoferrato (II) [Fe(CN)5(isn)]4- (isn= 4carboxilatopiridina ou isonicotinato), que devido a sua labilidade, foi utilizado na obtenção filmes de azul da Prússia a partir de deposição sobre eletrodos de carbono vítreo. Os filmes utilizados foram utilizados na determinação eletrocatalítica de ácido ascórbico, que é um analito de interesse biológico e industrial. A caracterização do complexo foi realizada através de espectroscopia eletrônica UV-Vis e espectroscopia vibracional na região do infravermelho, cujo espectro vibracional teórico apresentou grande concordância com os resultados experimentais, o que reforça a identidade do produto obtido. Outra técnica utilizada na caracterização do complexo foi a voltametria cíclica. Experimentos de cinética de substituição do ligante N-heterocíclico mostram que a reação de troca por DMSO ocorre por mecanismo dissociativo...

Correlation between pore size and reactivity of macro/mesoporous iron and copper hexacyanoferrates for H2O2 electrocatalysis

Gonçales, Vinicius R.; Gaitán, Martin Hernán; Bragatto, Allan de O.P.; Soler Illia, Galo Juan de Avila Arturo; Baraldo Victorica, Luis Mario; Córdoba de Torresi, Susana
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
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The effect of pore size to H2O2 detection by macroporous and mesoporous Prussian blue type electrocatalysts is reported in the present paper. The macroporous electrocatalysts were prepared employing spherical colloidal particles of different sizes (300, 460, 600 and 800 nm) as sacrificial templates to synthesize a copper hexacyanoferrate/polypyrrole (CuHCNFe/Ppy) hybrid material. Surprisingly, macroporous and non-porous CuHCNFe/Ppy displayed very similar results, which led to a discussion that application of macroporous platforms in sensors must consider the material wettability and the influence of electrochemical kinetics on analyte detection. In order to evaluate the effect of smaller pores, the performance of the macroporous H2O2 sensors was also compared to electrocatalysts synthesized through the immobilization of Prussian blue and CuHCNFe layers inside the cavities of mesoporous TiO2 films with diameters of 13, 20 and 40 nm. In this scale, the results were superior than those achieved with the non-porous sensors, demonstrating the possibility of controlling the performance of H2O2 sensors according to the pore diameter and the amount of immobilized material. Among the tested porous materials, the H2O2 sensor with better performance was achieved using the 20-nm diameter TiO2 platform functionalized with Prussian blue...

Prussian Blue as Prebiotic Reagent

Ruiz Bermejo, Marta; Menor-Salván, César; Veintemillas, Sabino
Fonte: NASA Astrobiology Institute Publicador: NASA Astrobiology Institute
Tipo: Póster Formato: 15475 bytes; application/pdf
ENG
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Poster presented at: Bioastronomy 2007: Molecules, Microbes and Extraterrestrial Life (July 16-20, 2007, San Juan de Puerto Rico).; Ferrocyanide has been proposed as a potential prebiotic reagent by Arrhenius. The complex salt named Prussian Blue, Fe4[Fe(CN)6]3, [ferric hexacyaneferrate (II)], might be an important reservoir of hydrogen cyanide, HCN, in the early Earth. HCN is a major product of spark discharge experiments on various gas mixtures; it is considered the main precursor of amino acids and purine bases under prebiotic conditions. The presence of banded iron formations shows that dissolved iron (ferrous iron) was present in high quantities in the ocean water during Archean epoch. Recently, we observed the formation of Prussian Blue in spark discharge experiments using saline solutions of ferrous chloride, FeCl3. Using Prussian Blue as starting material in ammonium solutions at different values of pH, and carrying out the reactions under middle conditions of temperature and concentration, some organic compounds were formed. We detected urea, imidazole, substituted imidazoles, methyl hydantoines and other heterocycles containing nitrogen and some amino acids by GC-MS of their trimethylsilyl derivatives. These results seem to indicate that Prussian Blue could be a sink of HCN in the early Earth. Subsequent reactions...

Corrosion Inhibition by Prussian Blue

Kalaivani,R.; Narayanaswamy,B.; Selvi,J. A.; Amalraj,A. J.; Jeyasundari,J.; Rajendran,S.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
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The inhibition efficiency (IE) of K3[Fe(CN)6] in controlling corrosion of carbon steel in aqueous solution containing 60 ppm of Cl- in the presence and absence of Zn2+ has been evaluated by weight loss method. The formulation consisting of 100 ppm K3[Fe(CN)6] and 50 ppm Zn2+ offers 98% inhibition efficiency to carbon steel immersed in aqueous solution containing 60 ppm Cl-. A synergistic effect exists between K3[Fe(CN)6] and Zn2+. As immersion period increases, the inhibition efficiency of K3[Fe(CN)6]─ Zn2+ system decreases. Polarization study reveals that this formulation controls the cathodic reaction predominantly. AC impedance spectra reveal that a protective film is formed on the metal surface. FTIR spectra reveal that the protective film consists of Prussian blue and Zn(OH)2. The film is found to be UV fluorescent.