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Highlights: [•] Stability of metal contaminated biodiesel blend has been checked. [•] Effectiveness of different antioxidants has also been checked. [•] Biodiesel blends with diesel have shown the better oxidation stability. [•] Effect of metals on the oxidation stability of biodiesel has found catalytic. [Copyright &y& Elsevier]

Abstract: The aim of the present study is to investigate engine performance and the exhaust emissions of a diesel engine using oxidatively stabilized biodiesel. Biodiesel fuel used in the study was prepared from Jatropha curcas oil. Different samples with various metal contaminants, generally available in the metallurgy of the containers are oxidatively stabilized with antioxidant (PY) according to EN 14112. The brake specific fuel consumption (BSFC) of biodiesel fuel with and without antioxidant is more than that of petro-diesel fuel. The BSFC of biodiesel fuel with antioxidants is lesser than that of biodiesel fuel without antioxidants, but no specific trends were detected according to the type of metal content and amount of antioxidants. The combustion characteristics and exhaust emissions in diesel engine were not influenced very much by the addition of antioxidants in biodiesel fuel. Also performance and emission characteristics of unstablized biodiesel and stabilized biodiesel (stabilized for 6months) are measured with respect to time. [Copyright &y& Elsevier]

Abstract: Recently, world has been confronted with an energy crisis due to fossil fuel depletion and environmental degradation. Biodiesel is one of the most promising alternative fuels to meet these problems. However the oxidation stability and thermal stability are the problems which are faced while we are going for commercial application of biodiesel. There are standards available discussing the minimum specification of oxidation stability of biodiesel while using in IC engine but at the same time there is no specification is available for thermal stability. Specification for thermal stability can be developed if one can develop the relationship between oxidation and thermal stability. The present paper deals with the development of relation between the oxidation stability and thermal stability which will further be useful for the development of such specifications for thermal stability of biodiesel. [Copyright &y& Elsevier]

Abstract: Biodiesel, an ecofriendly and renewable fuel substitute for diesel has been receiving the attention of researchers around the world. Due to heavy import of edible oil, the production of biodiesel from edible oil resources in India is not advisable. Therefore it is necessary to explore non-edible seed oils, like Jatropha curcas (J. curcas) and Pongamia for biodiesel production. The oxidation stability of biodiesel from J. curcas oil (JCO) is very poor and therefore an idea is given to increase the oxidation stability of biodiesel by blending it with petro-diesel. J. curcas biodiesel (JCB), when blended with petro diesel leads to a composition having efficient and improved oxidation stability. The results have shown that blending of JCB with diesel with less than 20% (v/v) would not need any antioxidants but at the same time, need large storage space. Similarly, if the amount of diesel is decreased in the blend, it will require the addition of antioxidant but in lesser amount compared to pure JCB. For the purpose five antioxidants were used namely butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), propyl gallate (PG), and pyrogallol (PY). A B30 blend (30% JCB in the blend of JCB and petro-diesel) has been tested for the same purpose. PY is found to be the best antioxidant among all five antioxidants used. The optimum amount of antioxidant (PY) for pure biodiesel tested for the present experiment is around 100ppm while it is around 50ppm for B30 blend to maintain the international specification of oxidation stability. [Copyright &y& Elsevier]

Abstract: The present paper deals with the study on the effect of metal contaminants on the oxidation stability of Jatropha curcas biodiesel (JCB). Taking pyrogallol as the most effective antioxidant based on the earlier work of the authors, JCB was mixed with different transition metals – Fe, Ni, Mn, Co and Cu in different concentrations. Induction period (IP) was measured using Rancimat method (EN 14112). Based on results, several correlations are developed for assessing the oxidation stability in terms of IP as a function of antioxidant and metal concentration. A comparison between the experimental IP values and those predicted by the correlation shows that about 95% of the predicted data points lie within ±10% deviation lines of the experimental results. This is the first study of its kind being reported showing the relationship of IP with antioxidant concentration and metal contaminants. The correlations developed can be used to predict the amount of antioxidants required to stabilize the JCB. [Copyright &y& Elsevier]

Biodiesel production is undergoing rapid technological reforms in industries and academia. This has become more obvious and relevant since the recent increase in the petroleum prices and the growing awareness relating to the environmental consequences of the fuel overdependency. However, the possibilities of production of biodiesel from edible oil resources in India is almost impossible, as primary need is to first meet the demand of edible oil that is already imported therefore it is essential to explore non-edible seed oils, like Jatropha curcas and Pongamia as biodiesel raw materials. The oxidation stability of biodiesel from Jatropha curcas oil is very poor. Therefore the aim of the present paper is to study the oxidation stability of Jatropha curcas biodiesel/ diesel blend. Also the effectiveness of various antioxidants is checked with respect to various blends of biodiesel with diesel. [ABSTRACT FROM AUTHOR]

Abstract: The vegetable oil, fats and their biodiesel suffer with the drawback of deterioration of its quality when it is in contact with oxygen unlike petroleum diesel. 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 all type of stability measuring test methods to find out the best method for stability measurement. From the review it is found that there are several methods to measure the stability of biodiesel but two test methods emerges the most likely choice for the purpose of measurement of oxidation stability of biodiesel. These are ASTM 2274 and 743 Rancimat test. A comparison between these two shows that these may be used alternatively. Most commonly used methods to investigate the thermal stability are Rancimat test, ASTM D 6408-08, D 5304-06 and TGA/DTA. Rancimat test has been suggested as an important method to measure the thermal stability of oils, fats and biodiesel fuels. [Copyright &y& Elsevier]

Abstract: Biodiesel consists of long chain fatty acid esters derived from feed stocks such as vegetable oils, animal fats and used frying oil, etc. which may contain more or less unsaturated fatty acids which are prone to oxidation accelerated by exposure to air during storage and at high temperature may yield polymerized compounds. Auto oxidation of biodiesel can cause degradation of fuel quality by affecting the stability parameters. Biodiesel stability includes oxidation, storage and thermal stability. Oxidation instability can led to the formation of oxidation products like aldehydes, alcohols, shorter chain carboxylic acids, insolubles, gum and sediment in the biodiesel. Thermal instability is concerned with the increased rate of oxidation at higher temperature which in turn, increases the weight of oil and fat due to the formation of insolubles. Storage stability is the ability of liquid fuel to resist change in its physical and chemical characteristics brought about by its interaction with its environment and may be affected by interaction with contaminants, light, factors causing sediment formation, changes in color and other changes that reduce the clarity of the fuel. These fuel instabilities give rise to formation of undesirable substances in biodiesel and its blends beyond acceptable quantities as per specifications and when such fuel is used in engine, it impairs the engine performance due to fuel filter plugging, injector fouling, deposit formation in engine combustion chamber and various components of the fuel system. The present review attempts to cover the different types of fuel stabilities, mechanism of occurrence and correlations/equations developed to investigate the impact of various stability parameters on the stability of the fuel. A review of the use of different types of natural and synthetic antioxidants has also been presented which indicates that natural antioxidants, being very sensitive to biodiesel production techniques and the distillation processes have varying impacts on fuel stability and available literature is very much scarce. The work on the use of synthetic antioxidants on the stability of biodiesel (both distilled and undistilled) from various resources has indicated that out of various 8 synthetic antioxidants studied so far only 3 antioxidants have been found to increase the fuel stability significantly. However, effectiveness of these antioxidants is in the order of TBHQ>PY>PG. [Copyright &y& Elsevier]

The national biofuel policy of the Indian government support to put a great emphasis on the synthesis of biodiesel from the nonedible feedstock. A potential option in this regard is Neem oil which is found in abundance in India (~1,00,000 tonnes). The major hindrance to the commercialization of biodiesel is its shelf life due to poor oxidation and stability characteristics. The current work investigates the oxidation stability of Neem biodiesel as per EU standard (EN14214) using the Rancimat apparatus. The oxidation stability of 12.3 hours without doping any chemical antioxidant in the synthesized Neem biodiesel makes it highly suitable for commercial acceptance. The impact of pyrogallol (PY) antioxidant was also investigated on the shelf life of Neem biodiesel build on response surface methodology (RSM) in accordance with Box-Behnken Design (BBD). Moreover, the execution and excretion characteristic of the Neem biodiesel blends: B15, B25, B35, and B45 are investigated on direct injection automotive compression ignition engine. Based on this broad experimental investigation B15 blend can be used as a fuel to power the existing automotive compression ignition engine with no compromise in the execution and excretion characteristics of the engine. From the analysis of the data of life-cycle assessment of the Neem biodiesel, it was found that it possesses the global warming potential of 45.72gCO2-eq Functional Unit−1 which is six times lesser than mineral diesel. Moreover, the Neem plantation has a carbon dioxide isolation potential of around 10 t ha−1 year −1. All these factors make the Neem Biodiesel highly suitable for blending with mineral diesel to power the existing compression ignition engines. [ABSTRACT FROM AUTHOR]