Determinação voltamétrica por redissolução anódica de Cu(II) em águas residuárias empregando um eletrodo de pasta de carbono modificado com quitosana

Janegitz, Bruno C.; Marcolino‐Júnior, Luiz H.; Fatibello‐Filho, Orlando

doi:10.1590/s0100-40422007000700033

Cited by 20 publications

(15 citation statements)

References 24 publications

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“…A pronounced increase of the peak current in the pH range of 2.5 and 3.5 is observed along with a decrease of peak current between 3.5 and 5.0. According to literature, 34 this result can be justified by the fact that the Cu 2+ ions undergo partial or total hydrolysis at pH higher than 3.5, decreasing the free Cu 2+ concentration, and subsequently decreasing the interaction with the electrode. Another suggestion is that, the decrease of the peak currents above pH 3.5 occurs due to lower stability of the Vulcan-CBZ material in pH values above 3.5, which makes it difficult the interaction between the Cu 2+ ions and the electrode surface (CPE/Vulcan-CBZ).…”

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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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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“…The versatility of chitosan is attributed to free amino groups, which are exposed after the deacetylation of chitin [31,32]. The preparation of chitosan microspheres is a strategy for increasing their adsorption capacity, once the microspheres have a surface area greater than the chitosan flake.…”

Section: State Of the Artmentioning

confidence: 99%

“…The development of analytical and electroanalytical techniques to determine low concentrations of metals in natural water and wastewaters have been of extreme interest. Janegitz et al (2007) developed a carbon paste electrode modified with chitosan, for the determination of Cu2+ in wastewater by voltammetry [31,32].…”

Section: State Of the Artmentioning

confidence: 99%

Water treatment: Chitosan associated with electrochemical methods

Tamiasso-Martinhon

Souza

Silva

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Pollution of water bodies due to the presence of toxic metals and organic compounds, bring out a series of environmental problems of public, government and social character. In addition, water pollution, has become the target and source of concern in many industrial sectors. Therefore, it is essential to develop technologies for treatment and purification of water. Chitosan is a natural product derived from chitin, extracted mainly from the shells of crustaceans. It is a low cost, renewable and biodegradable biopolymer of great socioeconomic and environmental importance. The classic treatment of wastewater containing metals involves physical chemistry processes of precipitation, ion exchange and electrochemistry. Electrochemical technology has been presented as the most promising methods for treating wastewater polluted with metals, colloids, dyes or oil in water emulsions; besides being used in removing organic compounds. Alternative methods like adsorption with biosorbents have been investigated. The great advantage of this latter over other techniques is the low generation of residues, easy recovery of metals and the possibility of reuse of the adsorbent. This article aimed to carry out an exploratory study, of bibliographical nature, on the use of chitosan in electrochemical methods for water treatment.

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“…Um campo que tem se destacado é o de desenvolvimento de novos eletrodos [29]. O desenvolvimento desses eletrodos se dá principalmente devido aos novos desafios impostos por amostras de interesse clínico, hospitalar, ambiental, alimentício, farmacêutico, entre outros [30,31].…”

Section: Introductionunclassified

“…Para obter uma maior eficácia das técnicas atuais, uma área que está aumentando a aplicabilidade e eficiência dos sensores eletroquímicos é a que compreende os chamados eletrodos quimicamente modificados (EQM) [31][32][33][34].…”

Section: Introductionunclassified

Determinação de catequinas por eletrodo de carbono impresso modificado com nanotubo de carbono funcionalizado

Silva

Kubota

et al. 2016

Eclet. Quim.

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____________________________________________________________________________Resumo: A Catequina é um composto fenólico com grande potencial oxidante, encontrada em diversos tipos de alimentos, dentre alguns dos benefícios da catequina estão o fortalecimento capilar, melhoria do fluxo sanguíneo, redução dos níveis de colesterol. Neste artigo, utilizou-se da técnica de voltametria cíclica (VC) para otimizar o eletrodo de carbono impresso modificado com nanotubo de carbono funcionalizado para detectar e quantificar catequina por meio da técnica de voltametria de onda quadrada (VOQ). Para este eletrodo, os melhores resultados foram obtidos a uma concentração de 1x10 -3 mol L -1 de catequina em meio de tampão fosfato 0,1 mol L -1 pH 7,0 a uma velocidade de varredura de potencial de 0,05 V s -1 . A partir destas condições foi obtida uma curva analítica com comportamento linear no intervalo de concentração de catequina entre 2,0x10 -7 a 1,68x10, com limites de detecção e de quantificação de 9,2x10 -8 e 3,0x10 -7 mol L -1, respectivamente por VOQ. Este eletrodo apresentou boa repetibilidade com um desvio de padrão relativo de 4,05%. A oxidação da catequina apresentou um pico localizado em torno de 0,15V vs Ag/AgCl, estando próximo dos potenciais de pico mostrados na literatura.Palavras-chave: catequina, eletrodo de carbono impresso, nanotubo de carbono, sensor eletroquímico ____________________________________________________________________________ Abstract: Catechin is a phenolic compound with high oxidizing potential, found in several types of foods, some of the benefits of catechins are capillary strengthening, improvement of blood flow and reduction of cholesterol levels. In this paper, it was used the cyclic voltammetry technique (CV) to optimize the printed carbon electrode modified with carbon nanotube, functionalized to detect and quantify catechin by means of the squarewave voltammetry technique (SWV). For this electrode, the best results were obtained at a catechin concentration of 1x10 -3 mol L -1 in means of 0.1 mol L -1 phosphate buffer pH 7.0 at a potential scan rate of 0.05 V s -1 . From these conditions, an analytical curve was obtained with a linear behavior in the catechin concentration range of 1,68x10 -5 to 2,0x10 -7 mol L -1, with limits of detection and quantification of 9,2x10 -8 and 3,0x10 -7 mol L -1 , respectively, by SWV. This electrode showed good repeatability with a standard deviation of 4.05%. Oxidation of catechin showed a peak located around 0,15V vs Ag / AgCl, being close to the peak potentials shown in the literature.

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Determinação voltamétrica por redissolução anódica de Cu(II) em águas residuárias empregando um eletrodo de pasta de carbono modificado com quitosana

Cited by 20 publications

References 24 publications

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

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

Water treatment: Chitosan associated with electrochemical methods

Determinação de catequinas por eletrodo de carbono impresso modificado com nanotubo de carbono funcionalizado

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