Estimation of the content of fatty acid methyl esters (FAME) in biodiesel samples from dynamic viscosity measurements

In order for biodiesel to be commercialized as pure biofuel or blending stock for diesel fuels, it must meet a set of requirements defined in standard specifications for a safe and satisfactory engine operation, one of these specifications is the content of fatty acid methyl esters (FAME). Besides, this parameter indicates the performance of the transesterification reaction for biofuel production from vegetable oils. There are several methods to determinate FAME content in biodiesel samples (chromatography, nuclear magnetic resonance spectroscopy and FTIR spectroscopy); however, they take long times and high cost for FAME content determination. From a practical point of view, in industrial biodiesel production is usually necessary to estimate the FAME value quickly. This paper presents correlations experimentally obtained from different oil feedstocks in order to estimate the biodiesel FAME content from the biodiesel dynamic viscosity, a fast determination parameter.     

生物柴油低温流动改进剂复配研究

采用碱催化法制备菜籽油生物柴油和棕榈油生物柴油,对其主要品质指标进行分析;考察了添加不同的柴油低温流动改进剂及其复配物对生物柴油低温流动性能的影响。结果表明,柴油低温流动改进剂能够改善生物柴油低温流动性能;将其进行复配后,能表现出协同效应,取得更好的降滤效果,尤其能使饱和脂肪酸甲酯含量高的棕榈油生物柴油冷滤点降低8℃;不同生物柴油对柴油低温流动改进剂或其复配物感受性存在较大差异,不饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类较多、分布较广的菜籽油生物柴油对单一低温流动改进剂感受性好,而饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类分布较集中的棕榈油生物柴油对复配物感受性好。     

Biodiesel production from Jerusalem artichoke (Helianthus Tuberosus L.) tuber by heterotrophic microalgae Chlorella protothecoides

BACKGROUND: As a potential source of biomass, Jerusalem artichoke has been studied for bioethanol production; however, thus far it has not been investigated for the production of other liquid biofuels, such as biodiesel. This work aims to develop a novel approach for biodiesel production from Jerusalem artichoke tuber using heterotrophic microalgae. RESULTS: In this study, Chlorella protothecoides utilized hydrolysate of Jerusalem artichoke tuber as carbon source and accumulated lipid in vivo, with lipid content as high as 44% by dry mass, and a carbon source to lipid conversion ratio of about 25% in a 4‐day scale cultivation. The lipids were extracted and then converted into biodiesel by transesterification. Cetane acid methyl ester, linoleic acid methyl ester and oleic acid methyl ester were the dominating components of the biodiesel produced. Unsaturated fatty acids methyl ester constituted over 82% of the total biodiesel content. CONCLUSION: This work suggests the feasibility of an alternative method of producing biodiesel from Jerusalem artichoke tuber using microalgae cultivation, and a cost reduction of carbon source feed in algal oil production can be expected. Copyright © 2009 Society of Chemical Industry     

Determination of Free Glycerol in Biodiesel via Solid-Phase Extraction and Spectrophotometric Analysis

To date, the standardized method for glycerol quantification in biodiesel production utilizes gas chromatography (GC); however, availability to manufacturers and instrumentation cost limits GC as an analytical method for general quality enforcement among producers. The method developed here is a bench top technique for quantitative determination of glycerol in biodiesel, with practical application in pharmaceutical and environmental quality control. The method extracts the glycerol contaminant from biodiesel using a normal phase solid phase extraction column (SPE). The protocol proceeds by rinsing with hexane to remove residual methyl esters, then collecting the glycerol with water. The aqueous extract is analyzed spectrophotometrically by an anthrone coloring reagent. Use of 2-g SPE columns and the solvent system developed has achieved 85% glycerol recovery. The assay applied has a detection range of 0.004–0.400% free glycerol, comparable to the established American Society of Testing and Materials (ASTM) D 6584-07 GC technique. Results were confirmed by GC and high-pressure liquid chromatography (HPLC). The bench top technique reduces the costs of operation relative to current methods, completes analysis in proficient time, requires minimal labor, and has analytical limits comparable to existing standard methods of biofuel analysis.     

生物柴油原料资源开发及深加工技术研究进展

生物柴油（脂肪酸甲酯）是一种绿色清洁的再生能源。我国生物柴油产业发展速度很快,但受原料价格高及产品多元化程度低等因素的影响,生物柴油价格高,产业缺乏竞争力。开发多样化的原料资源,进行产品深加工,对于生物柴油产业的发展具有重要的意义。本文综述了国内外生物柴油原料开发利用进展,介绍了国外生物柴油原料资源分布、资源特点及不同原料生物柴油的特点。简述了我国生物柴油原料资源现状及发展策略。介绍了生物柴油深加工技术研究进展,重点阐述了在制备第二代生物柴油、生物降解润滑油基础油、脂肪醇、烷醇酰胺、脂肪酸甲酯磺酸盐及绿色增塑剂等方面的研究进展及面临的问题,指出开发高效催化剂是发展生物柴油深加工技术的关键。     

Synthesis and Functional Evaluation of Soy Fatty Acid Methyl Ester Ketals as Bioplasticizers

A facile synthesis of the soy fatty acid methyl ester ketal has been accomplished using acetone in the presence of catalytic anhydrous ferric chloride starting from commercially available soy biodiesel (soy fatty acid methyl ester) after evaluating various synthetic procedures. The soy ketal product was fully characterized by nuclear magnetic resonance, infra-red and chromatography. The physical and analytical properties of soy ketal as determined by thermogravimetric analysis, viscosity acid and saponification values are acceptable for plasticizer applications. Soy ketal was compounded with polyvinyl chloride for evaluation of plasticizer properties such as efficiency, gelation, viscosity, volatility, thickening/aging behavior and stability. The thickening and aging behaviors of the soy ketal bioplasticizer are better than those of petroleum-based plasticizers such as diisononyl phthalate and diisononyl-cyclohexane dicarboxylate, but they need improvement in the areas of thermal stability and water extractability.     

Transesterification of vegetable oil to biodiesel fuel using alkaline catalyst

Biodiesel is gaining more and more importance as an attractive fuel due to the depleting fossil fuel resources. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst to give the corresponding monoalkyl esters. This article reports experimental data on the production of fatty acid methyl esters from vegetable oils, soybean and cottonseed oils using sodium hydroxide as alkaline catalyst. The variables affecting the yield and characteristics of the biodiesel produced from these vegetable oils were studied. The variables investigated were reaction time (1-3 h), catalyst concentration (0.5-1.5 w/wt%), and oil-to-methanol molar ratio (1:3-1:9). From the obtained results, the best yield percentage was obtained using a methanol/oil molar ratio of 6:1, sodium hydroxide as catalyst (1%) and 60 ± 1 °C temperature for 1 h. The yield of the fatty acid methyl ester (FAME) was determined according to HPLC. The composition of the FAME was determined according to gas chromatography. The biodiesel samples were physicochemically characterized. From the results it was clear that the produced biodiesel fuel was within the recommended standards of biodiesel fuel.     

Development and Validation of a Method for the Determination of Fatty Acid Methyl Ester Contents in Tung Biodiesel and Blends

The aim of this study was to develop and validate a method for the analysis of fatty acid methyl ester (FAMEs) content in tung biodiesel and blends with soybean biodiesel. The limits of detection (LOD) and quantification (LOQ), linearity, robustness, accuracy and precision were evaluated by using gas chromatography with mass spectrometry detection and impact electron ionization. The analytical curves showed correlation coefficients values higher than 0.99. The LOD and LOQ were 0.78 and 2.5 mg L⁻¹ for all FAMEs, respectively. The values of accuracy were between 86 and 117%, with relative standard deviation lower than 8%. The method was applied to tung biodiesel and tung and soybean biodiesel blends in the following proportions: 15:85, 20:80, 25:75 (%v/v). All of them showed good performance. Since the method was also applied to soybean biodiesel, the efficiency of the method for the analysis of both pure tung biodiesel and blends with different raw materials was confirmed and the robustness of the method was evidenced.     

Improving the economics of biodiesel production through the use of low value lipids as feedstocks: vegetable oil soapstock

Semirefined and refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high costs render the resulting fuels unable to compete with petroleum-derived fuel. We have investigated the production of fatty acid methyl esters (FAME; biodiesel) from soapstock (SS), a byproduct of edible oil refining that is substantially less expensive than edible-grade refined oils. Multiple approaches were taken in search of a route to the production of fatty acid methyl esters from soybean soapstock. The most effective method involved the complete saponification of the soapstock followed by acidulation using methods similar to those presently employed in industry. This resulted in an acid oil with a free fatty acid (FFA) content greater than 90%. These fatty acids were efficiently converted to methyl esters by acid-catalyzed esterification. The fatty acid composition of the resulting ester product reflected that of soy soapstock and was largely similar to that of soybean oil. Following a simple washing protocol, this preparation met the established specifications for biodiesel of the American Society for Testing and Materials. Engine emissions and performance during operation on soy soapstock biodiesel were comparable to those on biodiesel from soy oil. An economic analysis suggested that the production cost of soapstock biodiesel would be approximately US$ 0.41/l, a 25% reduction relative to the estimated cost of biodiesel produced from soy oil.     

Esterification of sludge palm oil using trifluoromethanesulfonic acid for preparation of biodiesel fuel

Trifluoromethanesulfonic acid (TFMSA) was used to reduce the high free fatty acids (FFA) content in sludge palm oil (SPO). The FFA content of SPO was converted to fatty acid methyl ester (FAME) via esterification reaction. The treated sludge palm oil was used as a raw material for biodiesel production by transesterification process. Several working parameters were optimized, such as dosage of catalyst, molar ratio, reaction temperature and time. Less than 2% of the FFA content was the targeted value. The results showed that the FFA content of SPO was reduced from 16% to less than 2% using the optimum conditions. The yield of the final product after the alkaline transesterification was 84% with 0.07% FFA and the ester content was 96.7%. All other properties met the international standard specifications for biodiesel quality such as EN 14214 and ASTM D6751.     

脂肪酸甲酯乙氧基化物中未反应脂肪酸甲酯的测定

采用气相色谱法(GC)测定了不同脂肪酸甲酯乙氧基化物(MEE)中未反应的脂肪酸甲酯的质量分数。以十三酸甲酯为内标，对不同MEE进行了定性和定量分析，同时以十二酸甲酯为标准考察了回收率。实验结果表明：该法相对标准偏差在1．2％以内，回收率大于96％。由测定结果可知：GC法简便、快速、准确率高、重现性好、能准确测定不同MEE中未反应脂肪酸甲酯的质量分数，可作为MEE产品质量监控的方法，也可为MEE新产品、新配方研究与开发提供有效的参考依据。     

Transesterification of rapeseed oil in subcritical methanol conditions

In this study, transesterification of rapeseed oil using subcritical methanol conditions was studied. The objective of the work was characterizing the methyl esters for its use as biodiesel in compression ignition motors. The variables affecting the methyl ester yield during the transesterification reaction, such as, the catalyst type and content, reaction temperature and pressure, the presence of hexane as co-solvent, the methanol oil molar ratio and the methanol hexane molar ratio were investigated to optimize the reaction conditions. The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, saponification value, iodine value, acidity index and water content, according to ISO norms. High methyl ester yield and fast reaction rate could be obtained even if the reaction pressure was relatively low, which is quite favorable to the production of biodiesel in industry.     

Ester content evaluation in biodiesel from animal fats and lauric oils

A modified method for the determination of ester contents of biodiesel based on EN 14103 has been developed. The method includes natural contents of heptadecanoic acid ester, which are found in animal fats and interfere with the standard method, into the calculation of ester content values. As a result, biodiesel samples prepared from waste animal fats and oils showed an increase in ester content between 2 and 7 wt‐% compared to values measured according to EN 14103. Furthermore, modifications of the GC temperature program made it possible to include also short‐chain fatty acid esters C₈–C₁₂, which can be found in coconut and palm kernel oil, into the calculation. Measurements showed that the ester content of such biodiesel differs by more than 40 wt‐% compared to EN 14103 determinations. However, also the stability of the internal standard solution methyl heptadecanoate influences the values of ester content. It can be demonstrated that after a period of 7 days, an ester content decrease of about 2 wt‐% can be observed. Therefore, the use of almost freshly prepared standard solutions should be recommended.     

Properties of a potential biofuel obtained from soybean oil by transmethylation with dimethyl carbonate

Biodiesel is a fuel generally consisting of a mixture of fatty acid methyl esters (FAMEs) which is used in alternative or in combination with petroleum diesel for its environmental benefits. Biodiesel is conveniently manufactured from vegetable oils by transesterification of triglycerides with methanol. However, the process brings about the concurrent formation of glycerol, which may become an oversupplied chemical if biodiesel production keeps growing. A novel biodiesel-like material (abbreviated as DMC-BioD) was developed by reacting soybean oil with dimethyl carbonate (DMC), which avoided the co-production of glycerol. The main difference between DMC-BioD and biodiesel produced from vegetable oil and methanol (MeOH-biodiesel) was the presence of fatty acid glycerol carbonate monoesters (FAGCs) in addition to FAMEs. In the following study, details regarding synthesis and composition of DMC-BioD are provided along with physical properties relevant for its use as a fuel. In addition, the production of potential pyrogenic contaminants was investigated by analytical pyrolysis and compared with those from MeOH-biodiesel, and the model compounds tristearin, triolein, trilinolein and oleic acid glycerol carbonate ester (OAGC). The presence of FAGCs influenced both fuel and flow properties, while the distribution of main pyrogenic compounds, including polycyclic aromatic hydrocarbons (PAHs), was little affected. Benefits and drawbacks of DMC as a candidate transmethylating reagent for producing biofuel from renewable resources and alternative co-products (glycerol carbonate and glycerol dicarbonate) are discussed.     

Biodiesel production using tetramethyl- and benzyltrimethyl ammonium hydroxides as strong base catalysts

In recent years, the acceptance of fatty acid methyl esters (biodiesel) as an alternative fuel has rapidly grown in EU. The most common method for biodiesel production is based on triglyceride transesterification to methyl esters with dissolved sodium hydroxide in methanol as catalyst. In this study, cottonseed oil and used frying oil were subjected to the transesterification reaction with tetramethyl ammonium hydroxide and benzyltrimethyl ammonium hydroxide as strong base catalysts. This work investigates the optimum conditions for biodiesel production using amine-based liquid catalysts. Biodiesel ester content was strongly related with the type of feedstock and the reaction variables, such as those of the catalyst concentration, methanol to oil molar ratio, and reaction time. The overall results suggested that the transesterification of cottonseed oil achieved high conversion rates with both catalysts, while the use of waste oil resulted in lower yields of methyl esters due to the possible formation of amides.     

Recovery of γ-oryzanol from biodiesel residue

γ-Oryzanol has important applications in food, cosmetic and pharmaceutical industries. The objective of this investigation is to isolate γ-oryzanol from residue obtained during the production of biodiesel from rice bran oil. Using rice bran oil as the feedstock, the content of γ-oryzanol could be raised to 16% by a series of steps, which include degumming and dewaxing, acid-catalyzed esterification and vacuum distillation. More than 95% low-boiling point components, such as free fatty acid and fatty acid methyl ester (biodiesel), were obtained as the distillate. After applying solvent extraction to the residue, γ-oryzanol content was increased from 16 to 35% with a recovery of 88%. Subsequent use of soxhlet extraction raised γ-oryzanol content to 47% with a recovery of 97%. Finally, after applying silica gel column chromatography, γ-oryzanol content was 83.79% with a recovery of 81.75%. The overall recovery was 69.82%.     

Transesterification of heated rapeseed oil for extending diesel fuel

Fatty acid methyl esters are well established as an alternative fuel called “biodiesel.” For economic reasons, used frying oil is an interesting alternative feedstock for biodiesel production. The chemical changes that occur during heating of rapeseed oil, especially the formation of polymers, were investigated. Heated rapeseed oil samples were transesterified with methanol and analyzed by size-exclusion chromatography. During heating, the amount of polymers in the starting oil increased up to 15 wt%, but only up to 5 wt% in the transesterified samples. So during transesterification, dimeric and trimeric triglycerides in the starting oil were mainly converted into monomeric and dimeric fatty acid methyl esters. The amount of polymeric fatty acid methyl esters had a negative influence on fuel characteristics. After 6 h of heating, the amount of Conradson carbon residue and after 16 h the viscosity exceeded that of the existing specifications for biodiesel. Therefore, the amount of polymers in waste oil is a good indicator for the suitability for biodiesel production. Presented in part at the 89th Annual Meeting, American Oil Chemists’ Society, Chicago, IL, May 1998.     

脂肪酸甲酯磺酸盐制备和分析方法的研究进展

介绍了SO3磺化法和磺氧化法两种制备脂肪酸甲酯磺酸盐(MES)的方法,重点介绍了MES产品中形成深色杂质的原因及MES主要成分的基本分析方法,如薄层色谱、毛细管电泳、色质联用、容量分析等;同时从原料、反应设备、反应过程、成色机理等方面阐述了几种不同的抑制MES产品中形成深色杂质的方法,并对MES的发展前景进行了展望.     

Rubber seed oil as a potential source for biodiesel production in Bangladesh

In the present paper, rubber seed oil (RSO) has been investigated as a potential source for biodiesel production in Bangladesh. Rubber seed oil has been extracted from the rubber seeds collected from the local garden. Different methods have been applied for the oil extraction, such as mechanical press with and without solvent and cold percolation. Maximum oil content of 49% has been found by mechanical press with periodic addition of solvent. The physico-chemical properties of the oil have been investigated. Effect of seed storage time on free fatty acid (FFA) content of the oil is studied an it is found that the FFA content increases from 2 wt.% (fresh seed) to 45 wt.% after 2 months of storage at room temperature. Biodiesel has been prepared using a three-step method comprises with saponification of oil, acidification of the soap and esterification of FFA. Overall yield of FFA from RSO is found to be around 86%. The final step is esterification that produces fatty acid methyl ester (FAME). The effect of methanol to oil ratio and catalyst content has been investigated for esterification reaction. ¹H NMR spectrum of the RSO and biodiesel samples are analyzed which confirms the conversion of RSO to biodiesel. The biodiesel properties have been investigated and are found to be comparable with diesel.     

Production and characterization of biodiesel from trap grease

The feasibility of the production of biodiesel from trap grease containing 51.5% free fatty acids (FFAs) was investigated. The esterification of FFAs by an acid catalyst followed by the transesterification of triglycerides by an alkali catalyst was examined. The esterification of trap grease by sulfuric acid as a homogeneous catalyst or by Amberlyst-15 as a heterogeneous catalyst was optimized through a response surface methodology. After the two-step esterification of trap grease by sulfuric acid, the acid value decreased from 102.9 mg KOH/g to 2.75 mg KOH/g. Through the transesterification by potassium hydroxide, fatty acid methyl ester (FAME) content reached 92.4%. Following the esterification of trap grease by Amberlyst-15, the acid value decreased to 3.23 mg KOH/g. With the transesterification by potassium hydroxide, FAME content increased to 94.1%. After the distillation of the produced biodiesel, FAME content increased again, to 97.6%. The oxidation stability of the trap grease biodiesel was 0.17 h, and its cold filter plugging point was 4 °C. As the FAME content of the trap grease biodiesel satisfies the Korean Biodiesel Standard, the trap grease biodiesel seems to be applicable for use as an engine fuel after properties improvement.