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.     

Novel biodiesel production technology from soybean soapstock

This paper describes an attractive method to make biodiesel from soybean soapstock (SS). A novel recovery technology of acid oil (AO) from SS has been developed with only sulfuric acid solution under the ambient temperature (25±2 °C). After drying, AO contained 50.0% FFA, 15.5% TAG, 6.9% DAG, 3.1% MAG, 0.8% water and other inert materials. The recovery yield of AO was about 97% (w/w) based on the total fatty acids of the SS. The acid oil could be directly converted into biodiesel at 95 °C in a pressurized reactor within 5 hours. Optimal esterification conditions were determined to be a weight ratio of 1 : 1.5 : 0.1 of AO/methanol/sulfuric acid. Higher reaction temperature helps to shorten the reaction time and requires less catalyst and methanol. Ester content of the biodiesel derived from AO through one-step acid catalyzed reaction is around 92%. After distillation, the purity of the biodiesel produced from AO is 97.6% which meets the Biodiesel Specification of Korea. The yield of purified biodiesel was 94% (w/w) based on the total fatty acids of the soapstock.     

Simple, high-efficiency synthesis of fatty acid methyl esters from soapstock

We report a simple method that efficiently esterifies the fatty acids in soapstock, an inexpensive, lipid-rich by-product of edible oil production. The process involves (i) alkaline hydrolysis of all lipid-linked fatty acid ester bonds and (ii) acid-catalyzed esterification of the resulting fatty acid sodium salts. Step (i) completely saponified all glycerides and phosphoglycerides in the soapstock. Following water removal, the resulting free fatty acid sodium salts were rapidly and quantitatively converted to fatty acid methyl esters (FAME) by incubation with methanol and sulfuric acid at 35°C and ambient pressure. Minimum molar reactant ratios for full esterification were fatty acids/methanol/sulfuric acid of 1∶30∶5. The esterification reaction was substantially complete within 10 min and was not inhibited by residual water contents up to ca. 10% in the saponified soapstock. The product FAME contained >99% fatty acid esters, 0% triglycerides, <0.05% diglycerides, <0.1% monoglycerides, and <0.8% free fatty acids. Free fatty acid levels were further reduced by washing with dilute sodium hydroxide. Free and total glycerol were <0.01 and <0.015%, respectively. The water content was <0.04%. These values meet the current specifications for biodiesel, a renewable substitute for petroleum-derived diesel fuel. The identities and proportions of fatty acid esters in the FAME reflected the fatty acid content of soybean lipids. Solids formed during the reaction contained 69.1% ash and 0.8% protein. Their sodium content indicated that sodium sulfate was the prime inorganic component. Carbohydrate was the predominant organic constituent of the solid.     

Production of FAME from acid oil,a by-product of vegetable oil refining

Simple alkyl FA esters have numerous uses, including serving as biodiesel, a fuel for compression ignition (diesel) engines. The use of acid-catalyzed esterification for the synthesis of FAME from acid oil, a by-product of edible vegetable oil refining that is produced from soapstock, was investigated. Soybean acid oil contained 59.3 wt% FFA, 28.0 wt% TAG, 4.4 wt% DAG, and less than 1% MAG. Maximum esterification occurred at 65°C and 26 h reaction at a molar ratio of total FA/methanol/sulfuric acid of 1∶15∶1.5. Residual unreacted species under these conditions, as a fraction of their content in unesterified acid oil, were FFA, 6.6%; TAG, 5.8%; and DAG, 2.6%. This corresponds to estimated concentrations of FFA, 3.2%; TAG, 1.3%; and DAG, 0.2%, on a mass basis, in the ester product. In an alternative approach, the acylglycerol species in soapstock were saponified prior to acidulation. High-acid (HA) acid oil made from this saponified soapstock had an FFA content of 96.2 wt% and no detectable TAG, DAG, or MAG. Optimal esterification conditions for HA acid oil at 65°C were a mole ratio of FFA/methanol/acid of 1∶1.8∶0.17, and 14 h incubation. FAME recovery under these conditions was 89% of theoretical, and the residual unesterified FFA content was approximately 20 mg/g. This was reduced to 3.5 mg/g, below the maximum FFA level allowed for biodiesel, by washing with NaCl, NaHCO₃, and Ca(OH)₂ solutions. Alternatively, by subjecting the unwashed ester layer to a second esterification, the FFA level was reduced to less than 2 mg/g. The acid value of this material exceeded the maximum allowed for biodiesel, but was reduced to an acceptable value by a brief wash with 0.5 N NaOH.     

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.     

Fourier Transform Near Infrared Spectroscopy as a Quality Control Tool for the Analysis of Lecithin and By-Products During Soybean Oil Processing

Fourier transform near infrared (FT-NIR) spectroscopy was used to analyze multiple measurement parameters in lecithin production samples and soybean oil refining by-products. For lecithin, partial least squares (PLS) calibration models were developed for acetone insolubles, acid value and moisture and leave-one-out cross validation of the calibration models yielded root mean square error of cross validation (RMSECV) values of 0.37%, 0.59 (mg KOH/g) and 0.050%, respectively. An independent test set consisting of 40% of the lecithin production samples were predicted from the PLS calibration models and a root mean square error of prediction (RMSEP) of 0.41%, 0.53 (mg KOH/g) and 0.056% were obtained for acetone insolubles, acid value and moisture, respectively. Comparison of FT-NIR predictions and corresponding reference method values of 10 lecithin samples using a two-tailed t test showed no significant difference at the p = 0.05 level. A set of 51 samples of soybean oil refining by-products, including acidulated soapstock, fatty acids and black oil, were used for developing PLS calibration models for measuring acid value, moisture and iodine value and leave-one-out cross validations for each model gave values for RMSECV of 6.59 (mg KOH/g), 0.046% and 0.42 (mg I₂/g), respectively. Overall, the results of this study demonstrate the suitability of FT-NIR spectroscopy for the routine analysis of lecithin production samples and soybean oil refining by-products for quality control purposes.     

超声辅助下皂脚加压水解制备脂肪酸

为了回收利用油脂精炼过程中产生的副产品皂脚中的有效成分,利用超声波辅助技术将皂脚一步转化为脂肪酸,意在考量超声波辅助技术在皂脚酸化水解过程中的作用,并在超声辅助下探究工艺条件的影响。以产物酸价和得率作为考察目标,探究了超声辅助酸化水解对产物分布的影响。结果表明,超声的分散搅拌作用使得产物的酸价和得率得到提升。通过单因素和正交设计实验探究各因素对产物酸价和得率的影响,进而确定制备脂肪酸的最佳反应条件。实验结果表明,以甲酸为酸催化剂,在反应温度220℃、反应时间110min、超声功率1050W、超声持续时间7s的反应条件下,产物酸价和得率均得到最高值,分别为184mg KOH/g和79.9%;影响产物得率的因素从主到次：反应温度>超声持续时间>超声功率>反应时间。经气相色谱质谱联用仪分析表明,产物中脂肪酸含量达到97.4%;产物质量指标测定结果表明产物具有较高的质量,皂化值达到190mg KOH/g,碘值达到157g I/100g,不皂化物含量达到0.54%。     

An ideal feedstock, kusum (Schleichera triguga) for preparation of biodiesel: Optimization of parameters

Kusum (Schleichera triguga), a non-edible oil bearing plant has been used as an ideal feedstock for biodiesel development in the present study. Various physical and chemical parameters of the raw oil and the fatty acid methyl esters derived have been tested to confirm its suitability as a biodiesel fuel. The fatty acid component of the oil was tested by gas chromatography. The acid value of the oil was determined by titration and was found to 21.30 mg KOH/g which required two step transesterification. Acid value was brought down by esterification using sulfuric acid (H₂SO₄) as a catalyst. Thereafter, alkaline transesterification was carried out using potassium hydroxide (KOH) as catalyst for conversion of kusum oil to its methyl esters. Various parameters such as molar ratio, amount of catalyst and reaction time were optimized and a high yield (95%) of biodiesel was achieved. The high conversion of the feedstock into esters was confirmed by analysis of the product on gas chromatograph-mass spectrometer (GC-MS). Viscosity and acid value of the product biodiesel were determined and found to be within the limits of ASTM D 6751 specifications. Elemental analysis of biodiesel showed presence of carbon, hydrogen, oxygen and absence of nitrogen and sulfur after purification. Molar ratio of methanol to oil was optimized and found to be 10:1 for acid esterification, and 8:1 for alkaline transesterification. The amounts of H₂SO₄ and KOH, 1% (v/v) and 0.7% (w/w), respectively, were found to be optimum for the reactions. The time duration of 1 h for acid esterification followed by another 1 h for alkaline transesterification at 50 ± 0.5 °C was optimum for synthesis of biodiesel.     

Effect of Lard Quality on Chemical Interesterification Catalyzed by KOH/Glycerol

The effects of water content, acid value, and peroxide value on interesterification catalyzed by potassium glycerolate (in situ KOH/glycerol) were investigated using lard as a model fat. SEM analysis of KOH/glycerol powder showed that numerous 0.5‐ to 5‐μm porous structures were formed and may play an important role in the interesterification reaction. Water content (up to 10 %, oil weight) and peroxide value (4.29 and 7.11 mmol/kg) significantly extended the induction period of interesterification but complete randomization was still achievable. However, when the acid value reached 5.13 mg KOH/g, complete deactivation of the catalyst was observed at 1 % catalyst content (by oil weight). The sn‐2 fatty acid composition of fully randomized lard was similar to that of non‐randomized lard. Interesterification resulted in substantial rearrangement of the triacylglycerol species and alteration of thermal behaviors. The interesterified lard exhibited a predominant β′ polymorph, as opposed to the dominating β‐form crystals found in the original lard.     

利用废食用油制备生物柴油的研究

对利用废食用油制备生物柴油的预酯化-酯交换工艺进行了研究。结果表明,预酯化的最佳工艺条件为：乙醇用量为80 mL、催化剂浓硫酸用量为1 g、反应时间为3 h、反应温度为70℃;酯交换的最佳工艺条件为：乙醇用量为60 mL、催化剂氢氧化钾用量1 g、反应时间为40 min、反应温度为70℃。在此条件下可使50 mL废食用油的酸值由40.27 mg KOH/g降到1.52 mg KOH/g,粗生物柴油的产率可达93.71%。     

Fuel properties of biodiesel produced from the crude fish oil from the soapstock of marine fish

The soapstock of a mixture of marine fish was used as the raw material to produce the biodiesel in this study. The soapstock was collected from discarded fish products. Crude fish oil was squeezed from the soapstock of the fish and refined by a series of processes. The refined fish oil was transesterified to produce biodiesel. The fuel properties of the biodiesel were analyzed. The experimental results showed that oleic acid (C18:1) and palmitic acid (C16:0) were the two major components of the marine fish-oil biodiesel. The biodiesel from the mixed marine fish oil contained a significantly greater amount of polyunsaturated fatty acids than did the biodiesel from waste cooking oil. In addition, the marine fish-oil biodiesel contained as high as 37.07 wt.% saturated fatty acids and 37.3 wt.% long chain fatty acids in the range between C20 and C22. Moreover, the marine fish-oil biodiesel appeared to have a larger acid number, a greater increase in the rate of peroxidization with the increase in the time that it was stored, greater kinematic viscosity, higher heating value, higher cetane index, more carbon residue, and a lower peroxide value, flash point, and distillation temperature than those of waste cooking-oil biodiesel.     

Comprehensive utilization of the mixture of oil sediments and soapstocks for producing FAME and phosphatides

Comprehensive utilization of the mixture of oil sediments (OS) and soapstock (SS) for producing FAME and phosphatides was investigated. A process consisting of three steps was employed for obtaining high conversion and by-product. In the first step, the OS–SS mixture was extracted with ethyl ether and the mixture was divided into three phases. The organic top phase contained triglycerides and phosphatides was extracted with cooled acetone and the acetone insoluble (phosphatides) was obtained. At the same time, triglycerides were separated also. In the second step, soap phase was then acidified with sulfuric acid to yield fatty acid. This “high-acid” acid oil was efficiently converted to methyl esters by acid-catalyzed esterification. The esterification reaction has been carried out with 5:1 methanol/oil (mol/mol) in the presence 3% H₂S0₄ (wt.%) as an acid catalyst at 85 °C for 5 h. FAME recovery under these conditions was 92.1% of theoretical. In the third step, alkaline catalyzed transesterification process converts the triglycerides to its mono-esters and glycerol. The optimized variables, 6:1 methanol/oil (mol/mol) with 1% NaOH (wt.%) reacted at 65 °C for 1 h, giving a maximum ester yield of 94%. Five important fuel properties of FAME from the OS–SS mixture were found to be comparable to those of No. 2 diesel fuel and conforming to both the American and German standards for biodiesel.     

Determination of the Fatty Acid Composition of Acorn (Quercus), Pistacia lentiscus Seeds Growing in Algeria

The fruits of two plants from Algeria (Quercus and Pistacia lentiscus) were investigated. The paper reports the chemical characteristics and the fatty acid composition of the oil extracts from the fruits. The black fruits of P. lentiscus has the highest crude fat of 32.8%, followed by the red fruits with 11.7%, and the lowest value of 9% in Quercus (acorn). The acid value was highest in red fruits of P. lentiscus oil (24.0 mg KOH/g), followed by the black fruits oil and lowest in acorn oil. The relatively high iodine value in the oils indicates the presence of many unsaturated bonds. Saponification value was highest in the Quercus ilex oil (166.7 mg KOH/g), while the lowest value was in the black fruits of P. lentiscus oil. Gas-liquid chromatography revealed that the three dominant fatty acids found are: palmitic C16:0 (16.3–19.5%), oleic C18:1 (55.3–64.9%), linoleic C18:2 (17.6–28.4%). The oils contain an appreciable amount of unsaturated fatty acids (78.8–83.5%).     

Iodine values of acidulated coconut oil soapstock

Summary Analyses and comparisons of a number of representative samples have shown that acidulated coconut oil soapstock may have an iodine value as much as 100% greater than that of the corresponding refined oil without any contamination being involved. Exactly what the spread between any given soapstock and oil will be apparently depends on the free fatty acid content of the original crude oil and the relative efficiency of the refining process. It was found that, for coconut soapstocks produced by standard laboratory refining tests, the relation between free fatty acid content and iodine value spread can be represented by the formula I.V. Spread=9.5–759 FFA. The efficiency of the refining process affects results insofar as it reduces the entrainment of neutral oil. Removing all of the neutral oil from four laboratory-produced soapstocks prior to acidulation raised the iodine value approximately two units in all cases. The practical significance of these results is obvious. A refiner processing high grade crude coconut oil of 9.5, iodine value by a highly efficient refining procedure cannot be expected to produce an acidulated soapstock of less than about 18.0 in iodine value. With higher free fatty acid crude oil and less efficient refining procedures lower iodine values are possible, but since soapstock is of minor economic value compared to refined oil, the trend will always be toward better grade crude oils and more efficient refining processes.     

Two approaches in preparation for cogeneration α‐tocopherol and biodiesel from cottonseed

A two‐step process and a direct alkaline transesterification process in preparation for cogeneration α‐tocopherol and biodiesel (fatty acid methyl esters, FAME) from cottonseeds were studied in this article. The effects of some factors on recovery of α‐tocopherol and conversion of cottonseed oil (triacylglycerols, TAGs) to biodiesel in the two processes were systematically studied by single factor experiments and orthogonal design method. In the two‐step process, α‐tocopherol and biodiesel were produced from extraction with two‐phase solvent followed by base‐catalysed transesterification. Approximately 95.5% TAGs was converted into biodiesel, and 1.008 mg/g (wet basis) α‐tocopherol was detected on the condition: 1:3 petroleum ether/methanol volume rate, 40°C extraction temperature; 7:1 methanol/cottonseed oil molar ratio, 1.1% KOH (w/v) concentration in methanol and 60°C esterification temperature. And in the direct alkaline transesterification reaction, 98.3% conversion of TAGs and 0.986 mg/g content of α‐tocopherol could be achieved at 60°C in 2 h. Both of the two processes were feasible from the economic point of view for further utilisation of cottonseed. © 2011 Canadian Society for Chemical Engineering     

微量酸催化麻疯树籽油制备生物柴油(英文)

Biodiesel produced from crude Jatropha curcas L.oil with trace sulfuric acid catalyst(0.02%-0.08% oil) was investigated at 135-184 ℃.Both esterification and transesterification can be well carried out simultane-ously.Factors affecting the process were investigated,which included the reaction temperature,reaction time,the molar ratio of alcohol to oil,catalyst amount,water content,free fatty acid(FFA) and fatty acid methyl ester(FAME) content.Under the conditions at 165 ℃,0.06%(by mass) H2SO4 of the oil mass,1.6 MPa and 20:1 methanol/oil ratio,the yield of glycerol reached 84.8% in 2 hours.FFA and FAME showed positive effect on the transesterification in certain extent.The water mass content below 1.0% did not show a noticeable effect on trans-esterification.Reaction kinetics in the range of 155 ℃ to 175 ℃ was also measured.     

两步法催化高酸价微藻油脂制备生物柴油

研究了两步法催化高酸价微藻油脂制备生物柴油的工艺条件。测定从产油栅藻培养物中提取的油脂的化学成分,发现油脂的游离脂肪酸含量分布在10%~32%,极性脂含量分布在21%~46%。以此高酸价、高极性脂含量油脂,经过酸预酯化-碱催化转酯化两步法制备生物柴油。其最优反应条件为:30%的醇加入量,1%油质量的硫酸催化反应2 h,其油脂酸价可从初始酸值的17~46 mg/g降低至2 mg/g以下;随后,在醇油物质的量之比为12:1,催化剂氢氧化钾用量为油质量的2%,65℃条件下反应30min,制备所得生物柴油中脂肪酸甲酯的质量分数可达96.6%,甘油三酯的转化效率接近100%。根据《柴油机燃料调合用生物柴油》国家标准,测定了微藻生物柴油产品的品质指标,发现其密度、运动黏度、酸价、氧化安定性等各项指标均符合国家标准(GB/T 20828-2007);热值为39.76 MJ/kg,符合欧盟生物柴油标准(EN 14214)。     

Characterization and Compositional Studies of Oil from Seeds of Desi Chickpea (Cicer arietinum L.) Cultivars Grown in Pakistan

The physiochemical properties and fatty acid (FA) composition of oil from seeds of four desi chickpea cultivars, grown in Pakistan, were investigated. The oil content was relatively low (5.88–6.87%). The physiochemical parameters determined included refractive indices (RI) at 40 °C (1.48–1.49), relative density (0.95–0.96), iodine value (IV) (111.87–113.69), acid value (AV) (2.55–2.73 mg KOH/g), saponification value (SV) (183.98–185.64 mg KOH/g), unsaponifiable matter (UM) (2.99–3.71%), peroxide value (PV) (3.97–6.37 mequiv/Kg), p-anisidine value (p-AV) (5.39–8.74), and oxidation value (OV) (13.67–22.34). Linoleic acid and oleic acid were the dominant FAs. Results from most of the parameters revealed significant (P < 0.05) differences among the cultivars. The findings reveal Desi chickpea (Cicer arietinum L.), indigenous to Pakistan, to be a potentially valuable legume crop with comparable nutritional quality oil.     

Production of biodiesel through optimized alkaline-catalyzed transesterification of rapeseed oil

Present work reports an optimized protocol for the production of biodiesel through alkaline-catalyzed transesterification of rapeseed oil. The reaction variables used were methanol/oil molar ratio (3:1-21:1), catalyst concentration (0.25-1.50%), temperature (35-65 °C), mixing intensity (180-600 rpm) and catalyst type. The evaluation of the transesterification process was followed by gas chromatographic analysis of the rapeseed oil fatty acid methyl esters (biodiesel) at different reaction times. The biodiesel with best yield and quality was produced at methanol/oil molar ratio, 6:1; potassium hydroxide catalyst concentration, 1.0%; mixing intensity, 600 rpm and reaction temperature 65 °C. The yield of the biodiesel produced under optimal condition was 95-96%. It was noted that greater or lower the concentration of KOH or methanol than the optimal values, the reaction either did not fully occur or lead to soap formation.The quality of the biodiesel produced was evaluated by the determinations of important properties such as density, specific gravity, kinematic viscosity, higher heating value, acid value, flash point, pour point, cloud point, combustion point, cold filter plugging point, cetane index, ash content, sulphur content, water content, copper strip corrosion value, distillation temperature and fatty acid composition. The produced biodiesel was found to exhibit fuel properties within the limits prescribed by the latest American Standards for Testing Material (ASTM) and European EN standards.     

Calcium oxide as a solid base catalyst for transesterification of soybean oil and its application to biodiesel production

In order to study solid base catalyst for biodiesel production with environmental benignity, transesterification of edible soybean oil with refluxing methanol was carried out in the presence of calcium oxide (CaO), -hydroxide (Ca(OH)₂), or -carbonate (CaCO₃). At 1 h of reaction time, yield of FAME was 93% for CaO, 12% for Ca(OH)₂, and 0% for CaCO₃. Under the same reacting condition, sodium hydroxide with the homogeneous catalysis brought about the complete conversion into FAME. Also, CaO was used for the further tests transesterifying waste cooking oil (WCO) with acid value of 5.1 mg-KOH/g. The yield of FAME was above 99% at 2 h of reaction time, but a portion of catalyst changed into calcium soap by reacting with free fatty acids included in WCO at initial stage of the transesterification. Owing to the neutralizing reaction of the catalyst, concentration of calcium in FAME increased from 187 ppm to 3065 ppm. By processing WCO at reflux of methanol in the presence of cation-exchange resin, only the free fatty acids could be converted into FAME. The transesterification of the processed WCO with acid value of 0.3 mg-KOH/g resulted in the production of FAME including calcium of 565 ppm.