Assessment of Oxidation Stability of Oils for Biodiesel Production (original) (raw)
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Oxidation Stability of Biodiesel
Oxidation stability of biodiesel is an important issue because fatty acid derivatives are more sensitive to oxidative degradation than mineral fuel. The vegetable oil, fats and their biodiesel suffer with the drawback of deterioration of its quality during long term storage unlike petroleum diesel due to large number of environmental and other factors making the fuel stability and quality questionable. There are various types of stabilities like oxidation, storage and thermal, playing key roles in making the fuel unstable. The present paper is an attempt to review the work done so far on the oxidation and thermal stability of biodiesel under different conditions. The effect of antioxidants on the stability parameters has also been reviewed in the present paper.
Evaluation of Biodiesel Oxidative Stability by Condutimetric Measurements
The biodiesel stability is an issue of great interest in whole world. In the present study, the oxidative resistances of biodiesel samples, originating from three fatty raw materials, are compared. Biodiesel samples were obtained from ethylic and methylic transesterification, at 70ºC, using refined sunflower, soybean and rapeseed oils and KOH as the catalytic agent. These samples were subjected to an accelerated oxidation test at 110ºC, under air flow. The produced gases were collected in a container with an electrode immersed in distilled water for electric conductivity measurements. For all the samples, it was observed the electric conductivity increases with time as an indicative of the formation of oxidative products such as alcohols, formic acid or smaller fatty acids. The samples stability decreased with increasing air flow. Comparatively, ethylic biodiesel samples seemed to be a little more resistant to degradation process in comparison to methylic biodiesel. Among all the samples, biodiesel obtained from rapeseed oil was more resistant to oxidative degradation, which is in accordance with the least content of C18:2 fatty acids in the respective raw material structure.
Energy & Fuels, 2014
Biodiesel can be described as a safe alternative fuel, which can replace petroleum diesel in the future. It consists of long-chain fatty acid methyl esters (FAME). Biodiesel has high lubricity and is a clean burning fuel. It also produces less air pollution, is renewable biodegradable, and is safer for the environment. Since biodiesel is produced from vegetable oil, animal fats, used cooking oil, and so forth, which may contain more or less unsaturated fatty acids that are prone to oxidation accelerated by exposure to air during storage and at high temperature, it may yield polymerized compounds. The oxidation and thermal stability of the fuel changes with storage time due to the formation of oxidation. Therefore, the aim of this study to evaluate the stabilities of biodiesel according to measured fuel properties, such as density, viscosity, flash point, total acid number (TAN), and total base number (TBN), by using various methodologies. In addition, oxidation stability of the samples was measured by the induction period using a Rancimat instrument. In this experiment, palm oil methyl ester (PME), palm biodiesel blend (40% PME and 60% diesel fuel), jatropha methyl ester (JME), jatropha biodiesel blend (40% JME and 60% diesel fuel), coconut oil methyl ester (COME), and conventional diesel fuel were used. Experiments were carried out at intervals over a 12-week test period. The experimental results for JME and PME showed similar performance in terms of flash point. All samples met the standard specification of the American Society for Testing and Materials (ASTM) D6751 (3 h) regarding the induction period, except for JME and its biodiesel blend, which did not meet the EN 14214 (6 h) standard specification. Among the fuel samples giving the worst results for TBN value due to oxidation, overall, among the biodiesels, PME and COME were found to give better results with respect to oxidation and storage stabilities.
Environmental Progress & Sustainable Energy, 2017
Among the 25 parameters established by the European Standard (EN14214:2012) to certify the quality of biodiesel, the oxidative stability is of concern, particularly when storing biodiesel for long periods. The products of biodiesel degradation are corrosive and lead to the formation of engine deposits that can block the filters and fuel injectors. Thus, EN14214:2012 establishes a period of 8 h for the oxidative stability of biodiesel. The main goal of this work is to study the effect of storage conditions in the oxidative stability of biodiesel and to understand how to control this property on the different stages of biodiesel production, namely through: (1) the use of different raw‐materials, blending, and production strategies; (2) the addition of antioxidants. NIR spectroscopy was used to follow the transesterification reaction and to analyze the different biodiesel samples. The storage conditions, such as sunlight exposure, temperature and presence of air, have a great impact on...
Energy, 2012
This paper presents the experimental results carried out to evaluate the oxidation and storage stabilities of various biodiesel fuels. The biodiesel fuels are palm methyl ester (PME), jatropha methyl ester (JME), coconut oil methyl ester (COME), 20% blends of PME with diesel fuel and 20% blends of JME with diesel fuel. The ordinary diesel fuel was used for comparison purposes. Various ASTM standard methods were used to evaluate all the samples at the interval of 180 h over a 2160 h (three months) duration. Oxidation stability of the samples was measured by induction period (IP) using a Rancimat instrument. Other properties such as density, viscosity, flash point, total acid number (TAN), and total base number (TBN) were measured. The results show that almost all fuel samples met the standard specifications regarding IP. The trends for density, viscosity and TAN increased, while the TBN decreased due to oxidation. For the flash point, the trend also decreased, but the rate was very low. In overall consideration, among the biodiesels, COME was found to be better in respect to oxidation and storage stabilities. The results of this investigation will be used to sustainable development of biodiesel fuel from various stock resources. © 2012 Elsevier Ltd. http://ac.els-cdn.com/S0360544212004124/1-s2.0-S0360544212004124-main.pdf?\_tid=bad6be82-a9c6-11e3-9b16-00000aacb35e&acdnat=1394615855\_356e3dfa1705ca817e5ebc81aa97ea8a www.sciencedirect.com/science/article/pii/S0360544212004124
Fuel Processing Technology, 2011
Biodiesel derived from free fatty acids (FFAs), which has the advantage of not competing with the edible-oil market, exhibited poor oxidation stability. The induction period (IP) of the FFA-based biodiesel determined by the Rancimat method at 110°C was 0.20 h. This study investigates the effectiveness of one natural and ten synthetic antioxidants, including α-tocopherol (α-T); butylated hydroxyanisole (BHA); butylated hydroxytoluene (BHT); 2, 5-di-tertbutylhydroquinone (DTBHQ); Ethanox 4740; Ethanox 4760E; 2,2′-methylene-bis-(4-methyl-6-tert-butylphenol) (MBMTBP); N,N′-di-sec-butyl-p-phenylenediamine (PDA); propyl gallate (PG); pyrogallol (PY); and tertbutylhydroquinone (TBHQ), at concentrations between 100 and 1000 ppm to improve the oxidation stability of the FFA-based biodiesel. The order of antioxidant effectiveness with respect to the oxidation stability of the FFAbased biodiesel was PYN Ethanox 4760EN PGN Ethanox 4740N PDA~BHAN BHT N MBMTBP~TBHQN DTBHQN α-T. The IP of the FFA-based biodiesel increased as the antioxidant concentration was increased and decreased at high test temperatures. Furthermore, the relationship between the IP values associated with the consumption of antioxidants in the FFA-based biodiesel was described by first-order reaction rate kinetics. However, the natural logarithm of IP (ln IP) at various concentrations of Ethanox 4760E showed a linear relation with the test temperature. The IP at ambient temperature was predicted based on the extrapolation method of the temperature dependence relation. After longterm storage at room temperature, the IP and acid value of the original FFA-based biodiesel significantly decreased and increased, respectively, with storage time, while the addition of antioxidants ensured the oxidation stability of the FFA-based biodiesel over 6 months of storage.
Talanta, 2011
Oxidation stability is an important quality parameter for biodiesel. In general, the methods used to evaluate the oxidation stability of oils and biodiesels are time-consuming. This work reports the use of spectrofluorimetry, a fast analytical technique, associated with multivariate data analysis as a powerful analytical tool to prediction of the oxidation stability. The prediction of the oxidation stability showed a good agreement with the results obtained by the EN14112 reference method Rancimat. The models presented high correlation (0.99276 and 0.97951) between real and predicted values. The R 2 values of 0.98557 and 0.95943 indicated the accuracy of the models to predict the oxidation stability of soy oil and soy biodiesel, respectively. The residual distribution does not follow a trend with respect to the predicted variables indicating the good quality of the fits.
<b>Oxidative stability of biodiesel blends derived from waste frying oils
Acta Scientiarum-technology, 2017
The high cost of biodiesel production is mainly linked to the price of raw material.This factor has favored the use of alternative fats and oils such as those used in frying. Since biodiesel can be obtained from several vegetable and animal raw materials, the physicochemical characteristics of the fuel may vary considerably. One of these characteristics is the fatty acid composition. It directly affects the oxidative stability of biodiesel, which can be impaired when the fuel undergoes exposure to sunlight, metals, oxygen and high temperatures. In order to improve the oxidative stability of biodiesels produced from waste frying oil some studies involving blends of different raw materials have been carried out. In this sense, this work aimed to assess the characteristics resulting from the blending of soybean waste frying oil with other waste biodiesels in what concerns to oxidation. The blends of fatty materials were obtained by means of a 2² factorial design. The induction periods of biodiesel blends were enough to meet the ASTM D6751 standard. Swine fat was responsible for the increase in the induction period values.
Oxidation Stability of Waste Cooking Oil Methyl Ester
2021
: Many researchers are attempting to develop an alternative fuel which is economical, environment friendly and a simple technology which is easy to understand and to implement. From the studies of many researchers we came to know that, biofuels are having the potential to serve as a fuel in compression ignition engine. In this review studies of various research pertaining to Oxidation stability of biodiesel is presented in detail. As oxidation stability is one of the major drawback in bringing biodiesel to main stream this review will assist in understanding this problem along with that also provides various solutions to overcome this problem.