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.

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SummaryThis paper deals with the effect of water and catalyst (KOH) amount on the quantity and quality of transesterification products of rapeseed oil by methanol, the methyl ester phase (i.e. yield, conversion), and the side-product, the glycerol phase (i.e. density, viscosity, the mass fraction of glycerol, esters, soaps). The dependencies were described by statistical

SummaryThe transesterification of vegetable oils (rapeseed oil was used) by low molecular alcohol is the most used method of biodiesel production. Since the reaction proceeds at the alcohol-oil interface, it is necessary to create a large interphase surface area using a special emulgation attachment. It was studied how the conditions (independent variables: molar ratio alcohol to oil, amount of used catalyst -KOH, time and temperature of reaction, intensity of stirring, revolution of emulgation attachment) affected the quality and quantity (dependent variables) of the ester phase -biodiesel.The amount of used catalyst was calculated with respect to the content of free fatty acid in oil. The statistical system of Plackett-Burman was used for experiment planning. Relationship between independent and dependent variables was found and described by multidimensional linear regression. Various statistical tests (principal component analysis, correlation matrix) were carried out, also.