Desenvolvimento de eletrodos modificados para determinação de compostos sulfurados em gasolina
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Data
2008-06-30
Autores
Martins, Diana Maria Serafim [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os compostos sulfurados no petróleo têm causado diversos problemas como os correlacionados à corrosão de equipamentos, envenenamento de catalisadores em processo de refino, qualidade dos produtos, além de liberação de gases tóxicos diretamente ao meio ambiente. Os compostos sulfurados em especial (enxofre elementar, difenil dissulfeto e 1-butanotiol) podem agravar estes problemas, sendo os principais causadores de corrosão de equipamentos nas refinarias de petróleo. Devido a tais considerações, a proposição deste trabalho é o desenvolvimento de metodologias eletroanalíticas para determinação de compostos sulfurados em gasolina, utilizando os eletrodos de filme de mercúrio, amálgama sólido e hexacianoferrato de cobre. No primeiro trabalho desenvolvido utilizou-se o eletrodo filme de mercúrio juntamente com as técnicas eletroanalíticas de voltametria de varredura linear (VVL), onda quadrada (VOQ) e pulso diferencial (VPD) em solução de acetato de sódio 1,4 mol L-1 e ácido acético 2% em metanol, como eletrólito suporte. O método apresentou limites de detecção na ordem de 10-9 a 10-4 mol L-1 para as técnicas eletroanalíticas de VVL, VOQ e VPD, inferiores aos já relatados na literatura usando método análogo. A quantificação dos compostos de enxofre em amostras de gasolina, a partir do monitoramento do sinal de redução sobre a superfície do eletrodo filme de mercúrio, utilizando a técnica de voltametria de onda quadrada, foi possível sem tratamento prévio da amostra, cujo procedimento mostrou ser bastante eficiente não provocando qualquer interferência associada aos constituintes da matriz, exibindo valores de 3,5x10-8, 3,7x10-7 e 4,2x10-8 mol L-1 para enxofre elementar, difenil dissulfeto e 1-butanotiol, respectivamente. A quantificação nas amostras de gasolina, avaliadas em termos...
The presence of sulfur compounds in petroleum has caused several problems including those related to the corrosion of equipments, and the quality of final products, as well as the emission of toxic gases to the environment. Sulfur compounds (elemental sulfur, diphenyl disulfide and 1-butanethiol), can increase these problems, being the main causes of corrosion of equipments in the refineries of petroleum. Based on these assumptions, the principal proposal of this work is the development of electroanalytical methodology for determination of sulfur compounds in gasoline using the electrodes of mercury film, amalgam solid and copper hexacyanoferrate. In the first developed work the mercury film electrode was used together with the electroanalytical techniques of linear scan voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) in solution of 1.4 mol L-1 sodium acetate and acetic acid 2% in methanol. The method presented detection limits in the order from 10-9 to 10-4 mol L-1 for the electroanalytical techniques of LSV, SWV and DPV. These limits are inferior to the previous related in the literature using similar method. The quantification of the sulfur compounds in gasoline samples, starting from the monitoring of the reduction sign on the mercury film electrode surface using the technique of square wave voltammetry was possible without previous sample treatment, whose procedure showed to be efficient, it not provoking any interference associated to the sample, exhibiting values of 3.5x10-8, 3.7x10-7 and 4.2x10-8 mol L-1 for elemental sulfur, diphenyl disulfide and 1-butanethiol, respectively. The quantification in the samples of gasoline in recovery terms showed that the methodology electroanalytical supplied quite acceptable results with recovery levels and precision compatible to the found by other techniques. In a second... (Complete abstract click electronic access below)
The presence of sulfur compounds in petroleum has caused several problems including those related to the corrosion of equipments, and the quality of final products, as well as the emission of toxic gases to the environment. Sulfur compounds (elemental sulfur, diphenyl disulfide and 1-butanethiol), can increase these problems, being the main causes of corrosion of equipments in the refineries of petroleum. Based on these assumptions, the principal proposal of this work is the development of electroanalytical methodology for determination of sulfur compounds in gasoline using the electrodes of mercury film, amalgam solid and copper hexacyanoferrate. In the first developed work the mercury film electrode was used together with the electroanalytical techniques of linear scan voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) in solution of 1.4 mol L-1 sodium acetate and acetic acid 2% in methanol. The method presented detection limits in the order from 10-9 to 10-4 mol L-1 for the electroanalytical techniques of LSV, SWV and DPV. These limits are inferior to the previous related in the literature using similar method. The quantification of the sulfur compounds in gasoline samples, starting from the monitoring of the reduction sign on the mercury film electrode surface using the technique of square wave voltammetry was possible without previous sample treatment, whose procedure showed to be efficient, it not provoking any interference associated to the sample, exhibiting values of 3.5x10-8, 3.7x10-7 and 4.2x10-8 mol L-1 for elemental sulfur, diphenyl disulfide and 1-butanethiol, respectively. The quantification in the samples of gasoline in recovery terms showed that the methodology electroanalytical supplied quite acceptable results with recovery levels and precision compatible to the found by other techniques. In a second... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Quimica analitica, Compostos sulfurados, Eletrodos modificados, Sulfur compounds
Como citar
MARTINS, Diana Maria Serafim. Desenvolvimento de eletrodos modificados para determinação de compostos sulfurados em gasolina. 2008. 166 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química., 2008.