Modified and Optimized Glass Electrode for pH Measurements in Hydrated Ethanol Fuel

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Fuel Quality Control

Background:

• pH is a critical quality control parameter for ethanol fuel.
• Existing standards (ABNT NBR 10891 for hydrated, ASTM D 6423 for anhydrous ethanol) have limitations.
• Liquid junction potential can affect pH measurement accuracy in ethanol fuels.

Purpose of the Study:

• To develop and optimize a modified electrode system for accurate pH measurement of hydrated ethanol fuel.
• To minimize the liquid junction potential in the measurement system.
• To compare the performance of the new system against existing standards and acid-base indicators.

Main Methods:

• A modified and optimized electrode structure using a single solvent was designed.
• Box-Behnken design was employed to determine optimal measurement conditions.
• Parametric and nonparametric statistical tests were used for comparison.

Main Results:

• The optimized system effectively minimized liquid junction potential.
• pH values obtained by the new system were statistically different from standard methods.
• The proposed method's pH values aligned with the range of acid-base indicators.
• The optimized electrode demonstrated adequate response sensitivity and operational behavior.

Conclusions:

• The modified and optimized electrode system provides accurate pH measurements for hydrated ethanol fuel.
• This new method offers an improvement over existing standard procedures.
• The system is suitable for quality control applications requiring precise pH determination.