title: Biodiesel transesterification kinetics monitored by pH measurement.
abstract: Quantification of a pH change that was observed over the course of the transesterification reaction that converts vegetable oil to biodiesel may provide a simple method to monitor the reaction. Transesterification of canola oil at 6:1 methanol to oil ratio with 0.5 wt.% KOH as catalyst was studied at 25, 35, and 45 °C. Reaction conversion was correlated to pH measurements and the results were shown to be in agreement with an independent measure of conversion using an enzymatic assay for glycerol. Rate constants obtained from these measurements are consistent with those in the literature. The measured pH change appears to be related to dilution of OH(-) ions as the oil is converted to products rather than to depletion of OH(-) due to reaction.
authors.affiliation: Chemical Engineering Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA. wmclark@wpi.edu
authors.forename: William M
authors.initials: WM
authors.lastname: Clark
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Medeiros
authors.forename: Donal J
authors.initials: DJ
authors.lastname: Boyd
authors.forename: Jared R
authors.initials: JR
authors.lastname: Snell
mesh_terms: D001671:Biochemistry / Q000379:methods*; D056804:Biofuels / Q000032:analysis; D004951:Esterification; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000494:pharmacology; D007700:Kinetics; D017680:Potassium Compounds / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
chemical_list: D056804:Biofuels; D006878:Hydroxides; D017680:Potassium Compounds; C029943:potassium hydroxide