A green and simple visual method for the determination of the acid-number of biodiesel

• Published in: Fuel (Guildford) Vol. 95; pp. 659 - 661
• Main Authors: Aricetti, Juliana Aparecida, Tubino, Matthieu
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-05-2012; Elsevier
• Subjects: Acid number; AOCS Cd 3d-63; Applied sciences; Biodiesel; Cadmium; Energy; Energy. Thermal use of fuels; Equivalence; Exact sciences and technology; Fuels; Green method; Isopropanol; Samples; Solvents; Titration; Visual; AOCS Cd 3d-63; Titration; Green method; Acid number; Biodiesel; Ethanol; Diesel fuel; Toluene; Biofuel; Comparative study
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2011.10.058

► Determination of the acid number of biodiesel. ► Acid–base titration. ► Green method. ► Ethanol and water used as solvents. ► Applied to biodiesels from soy, corn, canola, castor and sunflower oils and from swine lard.
A green and simple visual method is proposed for the determination of the acid number of biodiesel. The method was compared with that of the AOCS Cd 3d-63. The sample is dissolved in a 1:1 (v/v) ethanol:water mixture and phenolphthalein is added. This method replaces the use of the 1:1 (v/v) toluene:isopropanol mixture as solvent. The titration is performed with a 0.02molL−1 NaOH solution in water, avoiding the 0.1molL−1 KOH solution in isopropanol. A statistical comparison using the Student’s t and the Snedecor F tests showed that the proposed green method offers equivalent results to AOCS Cd 3d-63, with a little better precision.