Transesterification processes for vegetable oils: A simple control method of methyl ester content

Abstract

One of the main problems in the study or industrial application of transesterification processes for vegetable oils is how to measure the methyl ester content. In this work, a quick analytical method was developed for assessing the methyl ester content of purified "fuel grade" transesterification products by applying a simple correlation with viscosity. The correlation was tested on a wide range of samples with various methyl ester contents; the results were in agreement with the values measured by gas-chromatographic analysis. In a defined range of weight fractions the correlation allows for the determination of the methyl ester content of purified transesterification products by a single viscosity measurement. This method is especially suitable for process control purposes as it determines the methyl ester content quickly and simply.JAOCS 72, 1399-1404 (1995).KEY WORDS: Density measurement, diesel oil substitute, esterification, methyl ester density, methyl ester determination, EXPERIMENTAL PROCEDURESIn order to have samples with various degrees of purity, a number of transesterification reactions were caaa'ied out in the laboratory. The soybean oils used for transesteri;fication reactions were refined, edible-grade oils. Methanol, HPLC-grade (Aldrich, Steinheim, Germany), was used without further purification. These oils exhibited an average saponification number of 192, iodine number of 133, and an acid number of 0.06. Karl Fischer titration before use gave values <0.15% water. Reagent-grade sodium hydroxide was used as a catalyst.In order to determine the FAME and glyceride content of the transesterification products, sample preparation and GLC

Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

“…This behavior reflects in an increase of the molecular weight, polarity, steric hindrance and intermolecular forces. The obtained values are in agreement with those previously reported for ethyl esters 6,20 . The lower and higher refractive index values of the analyzed samples are respectively 1.4576 for pure biodiesel and 1.4737 for commercial soybean oil.…”

“…The ratio between the obtained intensities for the thirteen biodiesel samples to the measured intensities of the LED are used to characterize the biodiesel samples without intensity instability problems. The dynamic viscosity and the 1 H NMR analysis of all samples were taken using a Brookfield model LVDVIIICP (CP 42) Viscometer 6 and a Bruker Advance 200 MHz Spectrometer, using CDCl 3 as solvent and TMS as the internal standard, respectively.…”

“…The molecular weight of a typical ester molecule is roughly 1/3 that of a typical triglyceride molecule and therefore it presents a much lower viscosity 4,5 . The techniques for methyl or ethyl ester contents measurement in the final product of the transesterification process are not simple, affecting its uses in practical applications 6 . Fuel standards deal with quality issues of biodiesel by limiting material contents such as: free and total glycerol (total glycerol is the sum of free glycerol and glycerol bound as mono-, di-, and triacylglycerides), water, free fatty acid and residual alcohol.…”

Armazenamento, estabilidade oxidativa e caracterização do biodiesel metílico de soja

“…De acordo com Filippis et al [36] e Issariyakul e Dalai [10] fatores como reação incompleta, a presença de mono, di e triglicerídeos ou a presença de glicerina, devido à purificação ineficiente, promovem mudanças na viscosidade e na massa específica.…”

Thermogravimetric Approach for Assessing the Oxidation Level of a Biodiesel Sample

“…In addition, viscosity has been associated with the methyl ester content and the products of the transesterification reaction; 23 as a consequence, changes in biodiesel purity, due to oxidation, cause a change in viscosity.…”