ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 14 December 2010
Page Count: 9

New Methodology for pH Measurements in Fuel Ethanol Using Glass Electrode

Moutinho da Silva, Ricardo
Dept. of Analytical Chemistry, Institute of Chemistry, UNESP, Araraquara, São Paolo

Borges, Paulo Paschoal
Divisão de Metrologia Química, Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO), CEP: 25250-020, Rio de Janeiro, Rio de Janeiro

Fraga, Isabel Cristina Serta
Divisão de Metrologia Química, Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO), CEP: 25250-020, Rio de Janeiro, Rio de Janeiro

Stradiotto, Nelson Ramos
Dept. of Analytical Chemistry, Institute of Chemistry, UNESP, Araraquara, São Paolo

(Received 28 May 2010; accepted 28 October 2010)

Abstract

Studies carried out with glass electrode in anhydrous ethanol and ethanol-water solutions for measuring pH values have shown that this parameter depends on the solution composition, the contact time with the solution, the utilized temperature, and the type of electrolyte used. It was also observed that the glass electrode behavior in an acid medium differs from an alkaline medium. These studies provided correction factors for pH values from 2 to 12, allowing the realization of proper measurements of the hydrogen ionic activity in the ethanol-water and anhydrous ethanol solutions. However, these correction factors could not be applied to the fuel ethanol. Alternatively, a new method was developed for the correction of the pH values, which can be applied in hydrous and anhydrous fuel ethanol samples.

Keywords:
pH, ethanol-water solutions, glass electrode, fuel ethanol

Paper ID: JAI103192
DOI: 10.1520/JAI103192
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