The effect of the acidity of rapeseed oil on its transesterification

Abstract

SummaryThe aim of this work is to study the transesterification of vegetable oils with a high acid number. Rapeseed oil was used as the raw material and its acid number was changed by the adding of oleic acid (from 0.89 to 12.25 mg KOH/g). Methanol was used for transesterification (molar ratio of oil to methanol 1:6) and potassium hydroxide was used as a catalyst. After the reaction time, the residue of catalyst was neutralized by gaseous carbon dioxide and methanol excess was removed. After the separation of two phases, each of them was analyzed (in ester phase: yield, content of methylester and acid number; in glycerol phase: yield, density, viscosity, content of glycerol, soaps, methylester, potassium carbonate and hydrogen carbonate). The obtained data was compared with theoretical material balances and effect on saponification of oil was calculated. The results show that the yield of methylester (biodiesel) is significantly affected by higher acid number, as well as enhanced soap formation. On the other hand, the conversion of the oil and acid number of the ester phase remain at constant values in studied borders.

Combined effect of water and KOH on rapeseed oil methanolysis

“…Therefore, no kinetic models, equilibrium constants and concentrations of intermediates were needed. This work extends our previous work (Kwiecien et al, 2009) dealing with the effect of the oleic acid (formed neutralisation water respectively) artificially added into the oil by a statistical enumeration of water effect and also it is extended by the effect of the catalyst amount.…”

“…According to our previous work (Kwiecien et al, 2009), no conversion decrease was observed, whereas these two models for the conversion express the opposite. That could mean that the simulation of higher acidity (i.e.…”

“…The contributions of water in each component The chosen intervals of these two variables should extend the reaction conditions normally used according to Skopal et al (2001) and also cover the calculated values in the previous work of Kwiecien et al (2009).…”

“…Mass fractions of potassium carbonate, potassium hydrogen carbonate and soaps in GP were determined by acidometric titration with potentiometric indication and volumetric determination of carbon dioxide, according to Kwiecien et al (2009). 8…”

Magonia pubescens (Sapindaceae) Seed Oil: Physical and Chemical Properties, Fatty Acid Profile and Biodiesel Production

“…Although there are no official regulations for properties of oils used as raw material for biodiesel production, the acidity level is expected to be below 2 mg KOH·g -1 (Kwiecien et al, 2009). The moisture content found in M. Pubescens oil is 0.88%.…”