Crystallization behavior of fatty acid methyl esters and biodiesel based on differential scanning calorimetry and thermodynamic model

Biodiesel is mainly composed of methyl palmitate (MeC16), methyl stearate (MeC18), and methyl oleate (MeC18:1). In order to explore the crystallization behavior of biodiesel, the thermal parameters of the three fatty acid methyl esters, their binary mixtures, and biodiesel have been analyzed based on the differential scanning calorimeter. Supposing that biodiesel is a complex solution of various fatty acid methyl esters, the saturated fatty acid methyl esters MeC16 and MeC18 are treated as solutes and the unsaturated fatty acid methyl ester MeC18:1 is served as the solvent; thus a thermodynamic model according to the solid–liquid equilibria for predicting the crystallization onset temperature has been established. As a result, the model is effectively verified when the estimated crystallization onset temperatures for four types of actual biodiesel are compared with the experimental results.     

Lipase immobilization and production of fatty acid methyl esters from canola oil using immobilized lipase

Lipase enzyme from Aspergillus oryzae (EC 3.1.1.3) was immobilized onto a micro porous polymeric matrix which contains aldehyde functional groups and methyl esters of long chain fatty acids (biodiesel) were synthesized by transesterification of crude canola oil using immobilized lipase. Micro porous polymeric matrix was synthesized from styrene-divinylbenzene (STY-DVB) copolymers by using high internal phase emulsion technique and two different lipases, Lipozyme TL-100L^® and Novozym 388^®, were used for immobilization by both physical adsorption and covalent attachment. Biodiesel production was carried out with semi-continuous operation. Methanol was added into the reactor by three successive additions of 1:4 M equivalent of methanol to avoid enzyme inhibition. The transesterification reaction conditions were as follows: oil/alcohol molar ratio 1:4; temperature 40 °C and total reaction time 6 h. Lipozyme TL-100L^® lipase provided the highest yield of fatty acid methyl esters as 92%. Operational stability was determined with immobilized lipase and it indicated that a small enzyme deactivation occurred after used repeatedly for 10 consecutive batches with each of 24 h. Since the process is yet effective and enzyme does not leak out from the polymer, the method can be proposed for industrial applications.     

Castor oil biodiesel and its blends as alternative fuel

Intensive production and commercialization of biodiesel from edible-grade sources have raised some critical environmental concerns. In order to mitigate these environmental consequences, alternative oilseeds are being investigated as biodiesel feedstocks. Castor (Ricinus communis L.) is one of the most promising non-edible oil crops, due to its high annual seed production and yield, and since it can be grown on marginal land and in semi-arid climate. Still, few studies are available regarding its fuel-related properties in its pure form or as a blend with petrodiesel, many of which are due to its extremely high content of ricinoleic acid. In this study, the specifications in ASTM D6751 and D7467 which are related to the fatty acid composition of pure castor methyl esters (B100) and its blend with petrodiesel in a 10% vol ratio (B10) were investigated. Kinematic viscosity and distillation temperature of B100 (15.17 mm² s⁻¹ and 398.7 °C respectively) were the only two properties which did not meet the appropriate standard limits. In contrast, B10 met all the specifications. Still, ASTM D7467 requires that the pure biodiesel meets the requirements of ASTM D6751. This can limit the use of a wide range of feedstocks, including castor, as alternative fuel, especially due to the fact that in practice vehicles normally use low level blends of biodiesel and petrodiesel. These issues are discussed in depth in the present study.     

Optimization and oxidative stability of biodiesel production from rice bran oil

Biorefinery approach is introduced for the biodiesel production by utilizing low cost raw material, such as rice bran oil (RBO). The valorization of RBO was carried out by homogeneous transesterification process using response surface methodology (RSM) based on a two-variable central composition design (CCD). The process variables, temperature and catalyst concentration were found to have significant influence on biodiesel yield. The optimum combination derived via RSM for high ester yield (99.4%) was found to be 0.75% wt catalyst concentration at a reaction temperature of 45 °C. As biodiesel chemically is a long-chain alkyl methyl esters, its long-term fuel properties have become of great concern to the fuel industry. In order to determine the effects of long storage on oxidation stability, RBO biodiesel sample was stored for 24 months and the different physical–chemical properties were checked with respect to time. The results show that the acid value (AV), peroxide value (PV), and viscosity (ν) increased while the iodine value (IV) decreased. Based on results, correlations were obtained in terms of AV, IV, PV and ν as a function of time. Those correlations can be used to predict how long time biodiesel can safely be stored. AV, IV and PV of the biodiesel sample which was stored were within the limits in European biodiesel specifications (EN 14214).     

Lipase immobilized carbon nanotubes for conversion of Jatropha oil to fatty acid methyl esters

Lipase has been immobilized on multi-walled carbon nanotubes (MWCNTs) through the reaction of the carboxylated nanotubes with the enzyme in the presence of N-hydroxysulfosuccinimide (NHS) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride. Successful immobilization has been verified by infrared spectroscopy and scanning electron microscopy. The synthesized biomaterial has been used for catalyzing the conversion of Jatropha oil to the fatty acid methyl esters (FAME). Progress of the conversion reaction has been monitored with NIR spectroscopy. Gas chromatographic studies have indicated that the use of lipase–MWCNT bioconjuagate leads to almost quantitative conversion of Jatropha oil to the FAME. Around 1 h of the reaction, in the presence of around 15% of catalyst (mass fraction of catalyst on the total mixture), has yielded the desired results. The above used catalyst support has been regenerated 10 times without any adverse effect on the enzyme activity.     

The use of Koroch seed oil methyl ester blends as fuel in a diesel engine

An experimental investigation was carried out on a small direct injection (DI) diesel engine, fuelling the engine with 10% (B10), 20% (B20), 30% (B30) and 40% (B40) blending of Koroch seed oil methyl ester (KSOME) with diesel. The performance and combustion characteristics of the engine at various loads are compared and analyzed. The results showed higher brake specific fuel consumption (BSFC) and lower brake thermal efficiency (BTE) for the KSOME blends. The engine indicated power (IP) was more for the blends up to B30, but found to be reduced for the blend B40 when compared to that of diesel. The engine combustion parameters such as pressure crank angle diagram, peak pressure, time of occurrence of peak pressure, net heat-release rate, cumulative heat release, ignition delay and combustion duration were computed. The KSOME blends exhibited similar combustion trend with diesel. However, the blends showed an early start of combustion with shorter ignition delay period. The study reveals the suitability of KSOME blends up to B30 as fuel for a diesel engine mainly used in generating sets and the agricultural applications in India without any significant drop in engine performance.     

Unique occurrence of unusual fatty acid in the seed oil of Aegle marmelos Corre: Screening the rich source of seed oil for bio-energy production

In this work, an attempt has been made to characterize, isolate and elucidate the structure of unusual fatty acid in the seed oil of Aegle marmelos Corre. Further, this nonedible seed oil is screened for its bio-diesel or industrial feedstock property. The Aegle marmelos Corre seeds yielded 49.0% oil. The seed oil contains 12.5% of 12-hydroxyoctadec-cis-9-enoic acid (ricinoleic acid) along with other normal fatty acids. The identification and characterization was supported by FTIR, ¹H NMR, ¹³C NMR, MS, GC analysis and chemical degradation technique. A good agreement is seen between the calculated and experimental results of iodine value (IV) and saponification value (SV). The prominent parameters of bio-diesel such as cetane number (CN), lower heating value (LHV) and higher heating value (HHV) are deployed to envisage the quality of oil for use as bio-diesel. This seed oil is nonedible and is found to be the alternative feed stock for the production of bio-diesel since it convenes the major specifications of bio-diesel. The bio-diesel property of fatty acid methyl esters (FAMEs) of this seed oil is compared with other bio-diesels.     

High free fatty acid coconut oil as a potential feedstock for biodiesel production in Thailand

Coconut oil having 12.8% free fatty acid (FFA) was used as a feedstock to produce biodiesel by a two-step process. In the first step, FFA level of the coconut oil was reduced to 0.6% by acid-catalyzed esterification. In the second step, triglycerides in product from the first step were transesterified with methanol by using an alkaline catalyst to produce methyl esters and glycerol. Effect of parameters related to these processes was studied and optimized, including methanol-to-oil ratio, catalyst concentration, reaction temperature, and reaction time. Methyl ester content of the coconut biodiesel was determined by GC to be 98.4% under the optimum condition. The viscosity of coconut biodiesel product was very close to that of Thai petroleum diesel and other measured properties met the Thai biodiesel (B100) specification.     

Fuel properties of biodiesel from vegetable oils and oil mixtures. Influence of methyl esters distribution

In this work, the quality of biodiesel produced by basic transesterification from several vegetable oils (soybean, rapeseed, sunflower, high oleic sunflower, Cynara Cardunculus L., Brassica Carinata and Jatropha Curca) cultivated in Extremadura has been studied in detail. The influence of raw material composition on properties such as density, viscosity, cetane number, higher heating value, iodine and saponification values and cold filter plugging point has been verified. Other biodiesel properties such as acid value, water content and flash and combustion points were more dependent on characteristics of production process. Biodiesel produced by rapeseed, sunflower and high oleic sunflower oils transesterification have been biofuels with better properties according to Norm EN 14214. Finally, it has been tested that it is possible to use oils mixtures in biodiesel production in order to improve the biodiesel quality. In addition, with the same process conditions and knowing properties of biodiesel from pure oils; for biodiesel from oils mixtures, its methyl esters content, and therefore properties dependent this content can be predicted from a simple mathematical equation proposed in this work.     

Natural and synthetic antioxidants: Influence on the oxidative stability of biodiesel synthesized from non-edible oil

According to the proposed National Mission on Biodiesel in India, we have undertaken studies on the oxidative stability of biodiesel synthesized from tree borne non-edible oil seeds jatropha. Neat jatropha biodiesel exhibited oxidation stability of 3.95 h and research was conducted to investigate the influence of natural and synthetic antioxidants on the oxidation stability of jatropha methyl ester. Antioxidants namely α-tocopherol, tert-butylated hydroxytoluene, tert-butylated phenol derivative, octylated butylated diphenyl amine, and tert-butylhydroxquinone were doped to improve the oxidation stability. It was found that both types of antioxidants showed beneficial effects in increasing the oxidation stability of jatropha methyl ester, but comparatively, the synthetic antioxidants were found to be more effective.     

Transesterification of non-edible seed oil for biodiesel production: characterization and analysis of biodiesel

Evaluation of Radish (Raphanus sativus) seed oil (RSO) as a non-edible feedstock for biodiesel production was the main target of the present study. Extraction by solvent disclosed that radish seeds contains 33.50 wt.% of oil. Therefore, biodiesel production from it could be beneficial. Optimized base-catalyzed transesterification of RSO with methanol, ethanol and mixed methanol/ethanol was performed, to produce fatty acid methyl esters, fatty acid ethyl esters and mixed fatty acid methyl ethyl esters, respectively. The optimal yields of the methyl esters, ethyl esters and mixed methyl ethyl esters, were 95.55wt.%, 90.66 wt.% and 93.33 wt.%, respectively when the optimal reaction conditions were attained. Fuel properties of the parent oil were positively changed as consequence of transesterification reaction such that they fulfilled the standard limits as prescribed by ASTM D6751. Moreover, fuel properties of (biodiesels + petro diesel) blends conformed ASTM D7467-17 standards indicating their suitability as a fuel for diesel engines. Biodiesels form RSO were analyzed by thin layer chromatography and FTIR spectroscopy, and both techniques conformed its conversion into its corresponding alkyl esters.     

Performance and emission evaluation of a diesel engine fueled with methyl esters of rubber seed oil

Recent concerns over the environment, increasing fuel prices and scarcity of its supply have promoted the interest in development of the alternative sources for petroleum fuels. At present, biodiesel is commercially produced from the refined edible vegetable oils such as sunflower oil, palm oil and soybean oil, etc. by alkaline-catalyzed esterification process. This process is not suitable for production of biodiesel from many unrefined non-edible vegetable oils because of their high acid value. Hence, a two-step esterification method is developed to produce biodiesel from high FFA vegetable oils. The biodiesel production method consists of acid-catalyzed pretreatment followed by an alkaline-catalyzed transesterification. The important properties of methyl esters of rubber seed oil are compared with other esters and diesel. Pure rubber seed oil, diesel and biodiesel are used as fuels in the compression ignition engine and the performance and emission characteristics of the engine are analyzed. The lower blends of biodiesel increase the brake thermal efficiency and reduce the fuel consumption. The exhaust gas emissions are reduced with increase in biodiesel concentration. The experimental results proved that the use of biodiesel (produced from unrefined rubber seed oil) in compression ignition engines is a viable alternative to diesel.     

Study of degumming process and evaluation of oxidative stability of methyl and ethyl biodiesel of Jatropha curcas L. oil from three different Brazilian states

This work describes the production of biodiesel from Jatropha curcas oil. The kernel samples provided by Embrapa-PI, were first crushed in a blender and then subjected to extraction with hexane. The oil yield was between 54.71 ± 0.47 and 64.16 ± 2.88%. The J. curcas oil was then submitted to two different kinds of degumming, first with water and second with H₃PO₄ to evaluate the influence of these processes in the yield of the transesterification reaction. Methyl and ethyl biodiesel prepared from the degummed oil with H₃PO₄ had higher conversions than those prepared with the degummed with water. Therefore, among the processes of degumming studied, H₃PO₄ was more suitable for the treatment of J. curcas oil. The study shows the results about oxidation stability were good, because the biodiesels methyl and ethyl biodiesel have induction period at 13.51 h and 13.03 h without antioxidant addition when submitted a Rancimat text. Such biodiesels had their physicochemical parameters defined under the specifications of ANP Resolutions n° 14/2012 (ANP- National Agency of Petroleum, Natural Gas and Biofuels from Brazil). The results showed that J. curcas cultivation in Brazil is an adequate source for biodiesel production, considering the technical standards available.     

Performance of a domestic cooking wick stove using fatty acid methyl esters (FAME) from oil plants in Kenya

With depletion of solid biomass fuels and their rising costs in recent years, there has been a shift towards using kerosene and liquefied petroleum gas (LPG) for domestic cooking in Kenya. However, the use of kerosene is associated with health and safety problems. Therefore, it is necessary to develop a clean, safe and sustainable liquid bio-fuel. Plant oil derivatives fatty acid methyl esters (FAME) present such a promising solution. This paper presents the performance of a wick stove using FAME fuels derived from oil plants: Jatropha curcus L. (Physic nut), Croton megalocarpus Hutch, Calodendrum capense (L.f.) Thunb., Cocos nucifera L. (coconut), soyabeans and sunflower. The FAME performance tests were based on the standard water-boiling tests (WBT) and compared with kerosene. Unlike kerosene all FAME fuels burned with odorless and non-pungent smell generating an average firepower of 1095 W with specific fuel consumption of 44.6 g L^?1 (55% higher than kerosene). The flash points of the FAME fuels obtained were typically much higher (2.3–3.3 times) than kerosene implying that they are much safer to use than kerosene. From the results obtained, it was concluded that the FAME fuels have potential to provide safe and sustainable cooking liquid fuel in developing countries.     

Characterization and effect of using Mahua oil biodiesel as fuel in compression ignition engine

There is an increasing interest in India, to search for suitable alternative fuels that are environment friendly. This led to the choice of Mahua Oil (MO) as one of the main alternative fuels to diesel. In this investigation, Mahua Oil Biodiesel (MOB) and its blend with diesel were used as fuel in a single cylinder, direct injection and compression ignition engine. The MOB was prepared from MO by transesterification using methanol and potassium hydroxide. The fuel properties of MOB are close to the diesel and confirm to the ASTM standards. From the engine test analysis, it was observed that the MOB, B5 and B20 blend results in lower CO, HC and smoke emissions as compared to diesel. But the B5 and B20 blends results in higher efficiency as compared to MOB. Hence MOB or blends of MOB and diesel (B5 or B20) can be used as a substitute for diesel in diesel engines used in transportation as well as in the agriculture sector.     

Mahua oil (Madhuca Indica seed oil) methyl ester as biodiesel-preparation and emission characterstics

There is an increasing interest in many countries to search for suitable alternative fuels that are environment friendly. Although straight vegetable oils can be used in diesel engines, their high viscosities, low volatilities and poor cold flow properties have led to the investigation of various derivatives. Biodiesel is a fatty acid alkyl ester, which can be derived from any vegetable oil by transesterification. Biodiesel is a renewable, biodegradable and non-toxic fuel. In this study, Mahua oil (Madhuca indica seed oil) was transesterified with methanol using sodium hydroxide as catalyst to obtain mahua oil methyl ester. This biodiesel was tested in a single cylinder, four stroke, direct injection, constant speed, compression ignition diesel engine (Kirloskar) to evaluate the performance and emissions.     

Hydrogen addition to tea seed oil biodiesel: Performance and emission characteristics

Compression ignition engines are the dominant tools of the modern human life especially in the field of transportation. But, the increasing problematic issues such as decreasing reserves and environmental effects of diesel fuels which is the energy source of compression ignition engines forcing researchers to investigate alternative fuels for substitution or decreasing the dependency on fossil fuels. The mostly known alternative fuel is biodiesel fuel and many researchers are investigating the possible raw materials for biodiesel production. Also, hydrogen fuel is an alternative fuel which can be used in compression ignition engines for decreasing fuel consumption and hazardous exhaust emissions by enriching the fuel. In this study, influences of hydrogen enrichment to diesel and diesel tea seed oil biodiesel blends (B10 and B20) were investigated on an unmodified compression ignition engine experimentally. In consequence of the experiments, lower torque and higher brake specific fuel consumption data were measured when the engine was fuelled diesel biodiesel blends (B10 and B20) instead of diesel fuel. Also, diesel biodiesel blends increased CO₂ and NO_x emissions while decreasing the CO emissions. Hydrogen enrichment (5 l/m and 10 l/m) was improved the both torque and brake specific fuel consumption for all test fuels. Furthermore, hydrogen enrichment reduced CO and CO₂ emissions due to absence of carbon atoms in the chemical structure for all test fuels. Increasing flow rate of hydrogen fuel from 5 l/m to 10 l/m further improved performance measures and emitted harmful gases except NO_x. The most significant drawback of the hydrogen enrichment was the increased NO_x emissions.     

Fuel properties and exhaust emissions of low blending rate soybean oil methyl esters blended with diesel fuel

The main properties and engine emissions of low blending rate soybean oil methyl ester blended with diesel from 5 to 30 wt% were compared and analyzed. The experimental results show that, compared with diesel fuel, with an increase in the soybean oil methyl ester percentage in the blends, distillation temperature at 50%, flash point, kinematic viscosity, specific gravity, gelatine content, carbon residue, acidity and ash increase while a cold filter plugging point, solidifying point and copper corrosion keep constant, sulfur content decreases, smoke density and HC decrease while NO_x emission increase, CO increases at 2,200 r/min but decreases at 3,400 r/min.