O eletrólito suporte e suas múltiplas funções em processos de eletrodo

Agostinho, Sílvia Maria Leite; Villamil, Ruth Flávia Vera; Neto, Augusto Agostinho; Aranha, Hernani

doi:10.1590/s0100-40422004000500022

Cited by 38 publications

(36 citation statements)

References 11 publications

(16 reference statements)

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“…Eletrodos de carbono vítreo [21] e pasta de carbono [22] A escolha do eletrólito de suporte deve levar em conta a natureza do substrato empregado como eletrodo, bem como a natureza da investigação a ser realizada [33].…”

Section: Introductionunclassified

Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: Aplicação em águas de chuva de regiões de Santa Catarina

2012

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Neste estudo foi desenvolvida uma metodologia analítica para determinação de 2,4-dinitrofenol (2,4-DNP) em amostras de águas de chuva de regiões de Santa Catarina utilizando a voltametria de onda quadrada (VOQ) e de forma ex situ. O estudo envolveu a aplicabilidade de utilizar o eletrodo de carbono vítreo modificado com filme de bismuto. A formação do filme de bismuto foi otimizada por voltametria cíclica e em seguida, estudos de pH e eletrólito de suporte foram investigados para a redução do 2,4-DNP. Os parâmetros analíticos que afetam a sensibilidade da VOQ foram otimizados. Na sequência, as figuras analíticas de mérito foram obtidas: faixa linear de trabalho de 3,2 x 10-7 – 4,6 x 10-6 mol L-1, coeficiente de correlação de 0,996, RSD% = 17,5 (1,3 x 10-6 mol L-1, n = 6), 11,7 (2,5 x 10-6 mol L-1, n = 6) e 6,4 ( 4,5 x 10-6 mol L-1, n = 6), limite de detecção de 1,2 x 10-7 mol L-1. E, finalmente estudos de recuperação foram realizados para avaliar a exatidão da metodologia. Valores obtidos ficaram entre 84-112% (2,5 x 10-6 mol L-1) e 89 – 113% (4,5 x 10-6 mol L-1).

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Section: Introductionunclassified

Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: Aplicação em águas de chuva de regiões de Santa Catarina

2012

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“…This fact was expected, since the conductivity of the solution increases with the concentration of the electrolyte. 33 However, at the concentration between 0.2 and 0.4 mol L -1 , no significant variation in the analytical signal was observed. Thus, the 0.2 mol L -1 concentration of this electrolyte was chosen for the subsequent analysis.…”

Section: Influence Of Scan Ratementioning

confidence: 91%

Development of a Novel and Simple Electroanalytical Procedure for the Determination of Copper in Biofuel Employing a Sensor Based on Vulcan Functionalized with Carbazone

Freitas¹,

Lima²,

Marques³

et al. 2018

J. Braz. Chem. Soc.

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A novel and simple electroanalytical method for the determination of Cu 2+ in biodiesel samples by stripping voltammetric analysis was developed. The method employs a carbon paste electrode (CPE) modified with Vulcan carbon, previouly functionalized with carbazone (CBZ). The CPE/Vulcan-CBZ sensor promoted a significant increase in the analytical signal obtained from copper as compared to unmodified CPE, and the CPE modified with Vulcan carbon (CPE/ Vulcan). Vulcan-CBZ, Vulcan and CBZ materials were characterized by Fourier transform infrared spectroscopy (FTIR) technique. The electrochemical behavior of the sensor was evaluated using cyclic voltammetry (CV) and square-wave anodic stripping voltammetric (SWASV) techniques. The CPE/Vulcan-CBZ modified electrode showed excellent response and was able to detect Cu 2+ at nanomolar levels. The electrochemical method is based on preconcentration of Cu 2+ ions on the CPE/Vulcan-CBZ at 0.35 V vs. Ag/AgCl(sat) in 0.2 mol L -1 ammonium sulfate solution ((NH 4 ) 2 SO 4 ), pH 3.5, during 120 s, followed by subsequent chemical stripping. The analytical signal showed a linear response for Cu 2+ concentrations in the range from 6 to 190 nmol L -1 (r = 0.998), with a detection limit of 1.2 nmol L -1 . The sensor was successfully applied for the determination of Cu 2+ in biodiesel and the average recovery varied between 97.0 and 102.8% for the soybean biodiesel samples and between 109.6 and 111.0% for the babassu biodiesel samples showing a good accuracy for the proposed method.Keywords: biofuel, copper, voltammetric sensor, Vulcan carbon, carbazone IntroductionThe pursuit of alternative fuels has been acquiring prominence in the last decades. The replacement of fossil fuels has been motivated by environmental, economical and social factors, since society itself depends on its use. In this context, one alternative that has stood out is the use of biofuels, such as charcoal, alcohol, biogas and biodiesel. 1,2 Biodiesel is a renewable fuel produced either from vegetable sources (soybean, castor oil, palm oil, sunflower, among others) or from ethanol (from sugarcane) or methanol (which can be obtained from wood biomass). 3 It is, therefore, a biodegradable, sustainable and environmentally friendly fuel. However, some metals, such as Cu, Fe, and Ni, can be inserted in the production process with the catalysts, during transportation and storage. Furthermore, the presence of these metals, even at trace levels, can promote the formation of gums and sediments that damage vehicle engines and promote the oxidation of biodiesel. 4,5 Copper, iron and the effect of nickel on biodiesel's stability has been widely evaluated. Among these metals, copper is the most powerful catalyst in biodiesel's oxidation process. 5 Therefore, the monitoring of the amount of copper is extremely important in this fuel for preventing undesirable variations in its physical state and properties, during its use or storage. 5 In this context, it is opportune and necessary to develop novel sensitive and selective anal...

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“…The monovalent ion HSO 4 -displays its charge near the surface, thus increasing the electric field and the force of attraction exerted on the water molecules. Furthermore, the lower mobility of HSO 4 -causes steric hindrance of the active structure of the film, showing well-defined redox processes [37]. The amount of adsorbed material and the porous structure of the films affect the electrochemical activity of chemically modified electrodes.…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

Influence of Natural Polysaccharides on the Redox Processes of CuTsPc Thin Films and Dopamine Sensing

Moura¹

2013

IJMSA

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Abstract:Energy diagrams have been obtained for copper tetrasulfonated phthalocyanine (CuTsPc) from electrochemical and electronic absorption measurements in layer-by-layer (LbL) films with cashew (Anacardium occidentale L.) and angico branco (Anadenanthera colubrina) natural polysaccharides in the anionic layers. In this study, LbL films were produced with either copper tetrasulfonated phthalocyanine or polysaccharides (cashew or angico branco). Since CuTsPc and the gums are polyanions, the multilayer deposition was carried out in a tetralayer fashion, in which a conventional cationic polyelectrolyte, namely poly (allylamine hydrochloride) (PAH), was interposed between the polyanionic layers. An alternative for the simultaneous determination of electrochemical signals was using the deconvolution procedure. Mathematical deconvolution of the peaks followed Gaussian analysis. The presence of the gum led to increased adsorption of the phthalocyanine, and enhanced the UV-VIS absorption and electrochemical response of the films. Furthermore, modified electrodes based on polysaccharides/phthalocyanine films were able to detect dopamine at concentrations as low as 10 -5 mol/L.

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O eletrólito suporte e suas múltiplas funções em processos de eletrodo

Cited by 38 publications

References 11 publications

Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: Aplicação em águas de chuva de regiões de Santa Catarina

Desenvolvimento de metodologia analítica baseada em eletrodo de carbono vítreo modificado com filme de bismuto: Aplicação em águas de chuva de regiões de Santa Catarina

Development of a Novel and Simple Electroanalytical Procedure for the Determination of Copper in Biofuel Employing a Sensor Based on Vulcan Functionalized with Carbazone

Influence of Natural Polysaccharides on the Redox Processes of CuTsPc Thin Films and Dopamine Sensing

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