Effect of storage parameters on stability of Jatropha-derived biodiesel

Mazumdar et al. International Journal of Energy and Environmental Engineering 2013, 4:13 http://www.journal-ijeee.com/content/4/1/13 ORIGINAL RESEARCH Open Access Effect of storage parameters on stability of Jatropha-derived biodiesel Purabi Mazumdar1, Venu Babu Borugadda2, Vaibhav V Goud1,2* and Lingaraj Sahoo1,3* Abstract Jatropha curcas L. seeds as a raw material for biodiesel production is a rapidly growing interest over the world because of its high oil content, ecological adaptability, and excellent fuel properties. Though there is an increase in productivity of biodiesel, showing solution for future energy insecurity, there still remains some concern for commercialization due to its susceptibility to degradation during long storage. The aim of this paper is to investigate the effect of temperature and ambient condition on Jatropha biodiesel storage. An experiment was conducted for a period of 12 months, where Jatropha biodiesel stored in three groups at different temperatures (4°C, 25°C, and 35°C) and environmental conditions (exposed in dark, light, and air). At regular intervals, the samples were taken out to analyze acid value, density, kinematic viscosity, and thermogravimetric profile to monitor the quality of biodiesel. Analysis showed that acid value, density, kinematic viscosity, and the onset temperature of volatilization and distillation increases with the increase in storage time of biodiesel samples. However, Jatropha biodiesel stored at 35°C, in contact with ambient air and light showed highest degradation compared to those which were stored at 25°C and 4°C. Among all the parameters studied, high temperature and air exposure are the two most potent parameters which accelerate the degradation process. Along with that, light exposure had mild but significant effect on Jatropha biodiesel degradation over a long storage period. Keywords: Biodiesel, Jatropha curcas, Transesterification, Free fatty acids, TGA Background Biodiesel is a monoalkyl ester of long-chain fatty acid derived from vegetable oil or animal fat [1]. It constitutes the most reliable renewable source for substituting diesel. The finite nature of fossil fuel reserves and growing green house gas emission have promoted research on alternative fuels [2,3]. Biodiesel has advantages over conventional diesel fuels because of its renewable, environmentally benign and biodegradable nature. The main disadvantage is that biodiesels are severely prone to degradation than conventional diesel fuels during long storage [4]. Storage stability is a critical issue regarding the successful commercialization of biodiesel in fuel market. Storage stability is the ability of a fuel to resist changes in its physicochemical characteristics brought by interaction with its environment. In the presence of air or * Correspondence: ; 1 Center for Energy, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India 3 Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India Full list of author information is available at the end of the article oxygen, biodiesel will be hydrolyzed into alcohol and acid. The presence of alcohol reduces flash point, and the presence of acid increases the total acid value. All these make biodiesel unstable during storage. But in order to introduce biodiesel in the transport industry, it should meet accepted fuel standards and quality assurance [5]. There are various reports in the literature on the storage, oxidation stability, and the effect of antioxidant concentration on biodiesel. The effect of different synthetic and natural antioxidants on oxidation stability of biodiesel produced from rapeseed oil, sunflower oil, used frying oil, beef tallow, and soya bean oil has been reported [6,7]. Long time storage stability are also investigated on biodiesels synthesized from rapeseed oil, used frying oil, high oleic sunflower oil, high and low erucic Brassica carinata oil [5,8,9]. Dunn [10] examined the oxidative stability of soy-bean oil methyl esters by analyzing oil stability index Polavka et al. [11] studied the oxidation stability of rapeseed oil and waste frying oil methyl esters using differential thermal analysis and © 2013 Mazumdar et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Mazumdar et al. International Journal of Energy and Environmental Engineering 2013, 4:13 http://www.journal-ijeee.com/content/4/1/13 Rancimat (Metrohm AG, Herisau, Switzerland). Most of the studies on the storage and oxidation stability are carried out on biodiesel derived from edible oil. However, the studies on biodiesel derived from nonedible oil seeds are scanty [12-14]. Das et al. [12] analyzed the effect of light, air exposure, and antioxidants namely propyl gallate, butylatedhydrox-yanisole, and butylatedhydroxytoluene on long-term storage stability of karanja oil methyl ester (KOME). Their study showed that oxidative stability of KOME decreases with the increase in storage time and increases with higher concentration of antioxidant levels. Among non-edible oil crop, recently, Jatropha is in the top priority in national biodiesel program because of its high oil content and promising fuel properties. Several researchers have performed experiments for efficient Jatropha biodiesel production, physicochemical characterization [15,16], and engine performance [17]. Sarin et al. [18] monitored the effect of metal contaminants and antioxidant concentrations on the storage stability of Jatropha biodiesel. However, no proper study has been conducted on the effect of different storage parameters like temperature and exposure to light and air on Jatropha methyl ester (JME) storage. The aim of this work is to investigate the influence of different parameters like temperature and exposure to light and air on Jatropha biodiesel degradation. Acid value, density, kinematic viscosity (KV), and thermogravimetric analysis (TGA) results for methyl esters were analyzed for a period of 12 months and were compared with the initial values to monitor the changes in the quality of methyl esters. The study will provide knowledge on the factor influencing degradation of Jatropha biodiesel, which will be immensely helpful in maintaining the quality of Jatropha biodiesel over long-term storage. Methods Materials Jatropha seeds were collected from Assam, Northeast India. The seeds were separated from the fruit mechanically and cleaned manually to remove all foreign materials. Then, the seeds were dried under similar temperature (60°C) and humidity conditions to reach constant weight. The oil was extracted from grinded kernels in Soxhlet apparatus using hexane as per the standard American Oil Chemical Society procedure fo (...truncated)