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Master's Dissertation
DOI
https://doi.org/10.11606/D.75.2019.tde-27112019-173136
Document
Author
Full name
Suysia Ramos D'Almeida
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2019
Supervisor
Committee
Buoro, Rafael Martos (President)
Faria, Ronaldo Censi
Paixão, Thiago Regis Longo Cesar da
Sotomayor, Maria Del Pilar Taboada
Title in Portuguese
Desenvolvimento de eletrodos compósitos modificados com GO/PVI/PdNPs para determinação de p-nitrofenol em efluentes têxteis sintéticos
Keywords in Portuguese
p-nitrofenol
compósito
eletrodo de pasta de carbono
nanopartículas de paládio
óxido de grafeno
poli(vinilimidazol)
redução
Abstract in Portuguese

O presente trabalho disserta sobre o desenvolvimento de eletrodos à base de pasta de carbono modificados para a determinação eletroquímica de p-nitrofenol em amostras de efluentes têxteis sintéticos. Eletrodos de pasta de carbono (CPE) foram modificados com um material composto por óxido de grafeno, poli (vinilimidazol) e nanopartículas de paládio (GO/PVI/PdNPs) e caracterizados por Microscopia Eletrônica de Transmissão (TEM) acoplado com espectroscópica eletrônica de dispersão (EDS). A PdNPs foram encontradas bem distribuídas no suporte da matriz polimérica, com tamanho médio de 4,14 ± 1,61 nm. Os CPE foram desenvolvidos e modificados com o compósito nas proporções de 2,5%, 5%, 10% e 25% (m m-1) de GO/PVI/PdNPs: pó de grafite e mantendo 33,3% óleo mineral nujol (mT m-1) a fim de escolher a melhor proporção do modificador. Com base na melhor definição dos picos referentes aos processos anódicos e catódicos, optou-se em usar como modificador o eletrodo, na proporção de 10% (m m-1) na pasta. Este foi caracterizado eletroquimicamente por cronoculometria, voltametria cíclica. Ao modificar o eletrodo com GO/PVI/PdNPs-10% obteve-se um ganho de 2,3 vezes de área eletroativa comparando com CPE. Em resposta analítica as correntes de pico de redução do p-nitrofenol aumentaram linearmente com o aumento das suas concentrações na faixa de 10 a 170 µmol L-1, com R2 igual a 0,997 e os limites de detecção e quantificação (LOD) 2,20 µmol L-1 e (LOQ) 7,32 µmol L-1 para o GO/PVI/PdNPs-10%-CPEe a faixa linear entre 50 a 300 µmol L-1, com R2 igual a 0,982 e (LOD) 15,45 µmol L-1 e (LOQ) 51,56 µmol L-1 para o CPE. O GO/PVI/PdNPs-10%-CPE apresentou maior sensibilidade e menor desvio padrão das medidas comparado com o CPE. O eletrodo modificado permitiu uma boa recuperação para p-nitrifenol nas amostras de efluentes têxtil sintético, com valores de recuperação compreendidos entre 95,06 a 104,61% / (n = 8), atestando a exatidão do método proposto.

Title in English
Devolopment of composite eletrode modified with GO/PVI/PdNPs for determination of p-nitrophenol in synthetic textile efluents
Keywords in English
p-nitrophenol.
carbon paste electrode
composite
graphen oxide poly(vinylimidazole)
palladium nanoparticles
reduction
Abstract in English

The present work discusses the development of modified carbon-based electrodes for the determination of p-nitrophenol in synthetic textile effluent samples using electroanalytical techniques. The carbon paste electrodes (CPE) were modified with a material composed of graphene oxide, poly (vinylimidazole) and palladium nanoparticles (GO/PVI/ PdNPs). The GO/PVI/PdNPs composite was synthesized and characterized by Electron Transmission Electron Microscopy coupled with electron scattering spectroscopy (EDS). The PdNPs were well distributed in the polymer matrix support with an average size of 4 ± 2 nm. The CPE were developed and modified with the nanocomposite in the proportions of GO/PVI/PdNPs: 2.5%, 5.0%, 10.0% and 25.0% (m m-1): graphite powder and maintaining 33.3% mineral oil nujol (mT m-1) in order to choose the best proportion of the modifier. Based on the best definition of the peaks for the anodic and cathodeic processes, it was decided to use the electrode as a modifier in the proportion of 10% (m m-1) in the pulp. This was characterized electrochemically by chronoculometry and cyclic voltammetry. When modifying the GO/PVI/PdNPs-10%-CPE electrode, a gain of 2.3 times of electro-active area was obtained comparing with CPE. In an analytical response, the peak currents of p-nitrophenol reduction increased linearly with increasing concentrations in the range of 10 a 170 µmol L-1, with R2 equal to 0.997 and the limits of detection and quantification (LOD) of 2.20 L-1 and LOQ (7.32 µmol L-1) for (GO/PVI/PdNPs)-10%-CPE and the linear range between 50 and 300 µmol L-1, with R2 equal to 0,982 and (LOD) 15.45 µmol L-1) and (LOQ) 51.56 µmol L-1 for CPE. The GO/PVI/PdNPs-10%-CPE presented higher sensitivity and lower standard deviation of the measurements compared to CPE. The modified electrode allowed a good recovery for p-nitrophenol in the synthetic textile effluent samples, with recovery values ranging from 95.06 to 104.61% / (n = 8), attesting the accuracy of the proposed method.

 
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Publishing Date
2019-12-12
 
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