棉籽油基生物柴油铜片腐蚀特性

参照国家标准《发动机燃料铜片腐蚀试验方法》（GB/T378-1990）,在温度为25℃和50℃条件下,研究棉籽油基生物柴油铜片腐蚀特性,同时考察了棉籽油甲酯和乙酯理化性质的变化,并与0#柴油作了对比。结果表明：在25和50℃条件下,腐蚀试验历时2个月,棉籽油甲酯、乙酯对铜片具有不同的腐蚀现象,且棉籽油甲酯比乙酯的腐蚀性更大。在温度25℃条件下,棉籽油甲酯的铜片腐蚀率达到0.0926?cm/d,腐蚀后棉籽油甲酯的酸值、过氧化值、运动黏度分别提高10.4、1.44、1.13倍;温度升高到50℃时,棉籽油甲酯的铜片腐蚀率达到0.4115?cm/d,腐蚀后棉籽油甲酯的酸值、过氧化值、运动黏度分别增加12.8、2.16、1.13倍。温度升高,铜片腐蚀加剧,油品性质变化增大,乙酯生物柴油也具有类似的变化趋势,而0#柴油对铜片几乎无腐蚀。铜片的腐蚀是由生物柴油变质导致的。该研究可为棉籽生物柴油的工业化应用提供腐蚀数据。     

棉籽油生物柴油和柴油混合燃料的润滑特性

为研究生物柴油的润滑特性,该研究用棉籽油与甲醇和乙醇分别进行酯交换反应,制备出甲酯生物柴油和乙酯生物柴油。然后将它们分别以不同体积比率与市售0#柴油混合,制备出不同比率的生物柴油/柴油混合物。通过四球摩擦磨损试验机考察了这些混合物的润滑特性。结果表明：不同碳醇与棉籽油制备的生物柴油对柴油的润滑性能均具有增效作用,且随着生物柴油添加量的增加,柴油的润滑性能得到提高;但市售0#柴油对不同碳醇制备的生物柴油感受性不同,分别添加20%的甲酯生物柴油和乙酯生物柴油到0#柴油时,发现混合柴油的最大无卡咬负荷（PB值）分别提升了94.1%和29.4%;同时,甲酯生物柴油对柴油的最大无卡咬负荷影响大,而乙酯生物柴油/柴油的减摩性和抗磨性都好于甲酯生物柴油/柴油;游离脂肪酸对生物柴油润滑性也有较大影响。该研究为生物柴油的应用打下基础。     

脂肪酸甲酯生物柴油改善低硫柴油的润滑性能

生物柴油可作为改善低硫柴油润滑性能的天然添加剂。该文将豆蔻酸甲酯(C14:0)、棕榈酸甲酯(C16:0)、硬脂酸甲酯(C18:0)、油酸甲酯(C18:1)、亚油酸甲酯(C18:2)、亚麻酸甲酯(C18:3)、蓖麻醇酸甲酯(C18:1 OH)及蓖麻油甲酯和餐饮废油甲酯按照0.5%、1.0%、1.5%和3.0%的体积分数添加到低硫柴油中,在高频往复试验机(high-frequency reciprocating rig,HFRR)上进行润滑性能测试,探究脂肪酸甲酯的碳链长度、不饱和度及含羟基等结构特征对润滑性能的影响。结果表明,长碳链脂肪酸甲酯一般比短链润滑效果好;碳链长度为十八的脂肪酸酯中,不饱和程度即碳碳双键数目越高则润滑性能越好;而在相同碳链长度和不饱和度条件下,含羟基的蓖麻醇酸甲酯的润滑改善效果优于油酸甲酯。由多种脂肪酸酯构成的混合物生物柴油的润滑性能要优于某单一的纯脂肪酸甲酯。在低硫柴油中,当某饱和脂肪酸甲酯的体积分数比例达3.0%时,或不饱和酯的体积分数达到1.5%时,或生物柴油的体积分数达1.0%时,可使低硫柴油的润滑性能指标满足相关标准。研究脂肪酸甲酯的各种结构特征对其润滑性能的影响及作用机制,有助于筛选合适的生物柴油组分及其添加浓度作为低硫柴油的润滑添加剂。     

废气再循环改善生物柴油发电机的经济性和排放性

在单缸风冷四冲程柴油发电机上,采用0、16%、28%EGR(exhaust gas recirculation,废气再循环)率,分别以柴油和生物柴油为燃料进行了试验,测试并分析了经济性,NOx、HC、CO和烟度的排放性能。研究表明:生物柴油油耗高于柴油,在0、16%和28%EGR率时,生物柴油的体积油耗平均高出柴油约9%、10%和17%;与无废气再循环相比,16%和28%EGR率时,燃用柴油平均可减少NOx约17%和35%,燃用生物柴油平均可减少NOx约10%和24%,生物柴油的NOx排放量高于柴油平均约6.5%和17%;燃用柴油时随EGR率增大,HC的排放量增大,16%和28%EGR率时,生物柴油的HC排放低于柴油平均约6%和28.5%;28%EGR率时,生物柴油CO排放量低于柴油,平均降低约24%;随EGR率增大,生物柴油的烟度增大,燃用生物柴油在小负荷和中负荷时烟度高于柴油。     

菜籽油碱催化法制备生物柴油的工艺参数

以碱催化剂为媒介的转酯化反应制备生物柴油方法因其转化率高而倍受重视。该文以菜籽油为原料,在小型试验装置上,采用均相碱催化法,研究了菜籽油在碱性催化剂NaOH的作用下与甲醇经酯交换反应制备生物柴油的工艺条件。考察了醇油摩尔比（4︰1～8︰1）、催化剂用量（0.5%～2%）、反应温度（30～60℃）和反应时间（30～150 min）等工艺参数对酯交换反应的影响,对生物柴油的组成成分进行了气相色谱/质谱联用(GC-MS)分析。结果表明,在醇油摩尔比6︰1,催化剂用量为油质量的1%,反应温度为50～60℃,反应时间为60 min时,酯交换反应转化率最高可达到96.7%。该生物柴油主要由油酸甲酯、芥子酸甲酯、9,12-十八碳二烯酸甲酯、11-二十碳烯酸甲酯、亚麻酸甲酯等脂肪酸甲酯组成,其中油酸甲酯含量最高,相对质量分数高达50.30%。     

固体碱催化棉籽油制备生物柴油

为研究采用固体碱催化剂催化制备生物柴油的相关技术,以棉籽油为对象,选用Na3PO4/MgO负载型固体碱为催化剂,以棉籽油的生物柴油转换率为指标,通过单因素和正交试验,分析催化剂的最佳制备工艺,并对催化剂进行X射线衍射、扫描电镜和热重表征分析。在此基础上对该催化剂催化棉籽油制备生物柴油的工艺进行探讨。研究结果表明,催化剂的最佳制备工艺为：Na3PO4负载量32%,焙烧温度600℃,焙烧时间3 h,共混温度70℃;使用优选的催化剂制备生物柴油的工艺条件为：反应时间2.5 h,反应温度70℃,醇油摩尔比15∶1,催化剂用量5%;催化剂的活性与Na3PO4晶相有关。     

生物油/柴油乳化燃料的燃烧特性

为了研究生物油/柴油乳化燃料的燃烧特性,利用非离子表面活性剂复配,对热解生物油/柴油混合液进行了乳化,测量了乳化燃料的密度、热值、动力黏度及pH值。在SD1110型柴油机台架上进行4种不同配比的生物油/柴油乳化燃料的发动机台架试验,得出了柴油机燃用生物油/柴油乳化燃料和纯柴油的负荷特性和排放特性曲线,并且对乳化燃料和纯柴油的排放特性进行了对比。研究结果表明：生物油体积分数为20%的乳化燃料当量油耗率最低,乳化燃料CO的排放高于柴油的排放,且生物油含量越高CO排放越大,而乳化燃料的NO及碳烟的排放则优于纯柴油的排放。由于生物油/柴油乳化燃料的理化特性与柴油接近,可以作为普通柴油机的燃油使用。     

生物质混合燃料在柴油机喷嘴内流动特性模拟

为了研究燃料物性差异对喷孔内流动特性的影响,通过GAMBIT软件建立三维喷嘴模型,利用FLUENT软件采用混合多相流模型,对柴油、生物柴油、生物柴油/乙醇混合燃料的喷孔内压强分布、速度分布和空化程度进行仿真分析。结果表明:燃油在压力室与喷孔入口衔接处压强迅速下降,进入喷孔后压强趋于稳定,在喷孔出口处压强略有上升;生物柴油的压强降幅最大,在喷孔不同截面处,与柴油相比生物柴油的压强平均下降了23.91%;生物柴油/乙醇混合燃料与柴油的压强降幅差别不大。燃油流速在喷孔入口处迅速增加,进入喷孔后增速放缓,在喷孔出口处燃油流速略有下降;在喷孔径向方向,由于壁面黏滞力作用导致速度从中心轴线向外围呈递减趋势;在喷孔不同截面处柴油的流速最快,其在喷嘴出口处的流速为229.8 m/s;生物柴油/乙醇混合燃料在喷嘴出口处的流速为223.1 m/s;生物柴油的流速最小,其在喷嘴出口处的流速为214.9 m/s。空穴现象首先发生在喷孔入口拐角处,随后向喷孔出口发展,并逐渐减弱。喷孔不同截面处,柴油的气相体积分数最大,生物柴油的气相体积分数最小,其气相体积分数比柴油平均下降了11.1%,与柴油相比生物柴油的空化程度较弱;生物柴油/乙醇混合燃料的气相体积分数与柴油差别不大,仅降低了1.8%,在生物柴油中添加乙醇能够降低燃料的密度、粘度和表面张力,改善燃料在喷孔内的流动特性,促进空化产生,喷孔内的空化现象能够为圆射流喷雾提供初始扰动,促进燃油雾化。该研究可为生物柴油/乙醇混合燃料流通特性研究提供理论支持。     

文冠果生物柴油的生产工艺及其理化性能

该文以生产达标的文冠果生物柴油为目的。通过设计其生产工艺流程,分别在转化温度为60和70℃的条件下生产了2种生物柴油,并测定了0#柴油分别与2种生物柴油以一系列不同掺混比(0、10%、20%、30%、40%、50%、60%、70%、80%、90%、100%)混合的燃料的理化性质(密度、运动黏度、闪点、凝点和馏程)。结果表明:转化温度为70℃的生物柴油各理化性能要优于转化温度为60℃的生物柴油;生产的2种生物柴油与0#柴油在掺混比不超过20%时,各项理化性能指标均符合国家车用柴油标准,达到应用要求。     

高原缺氧环境下生物质燃料对柴油机性能和排放的影响

为了研究不同类别的含氧生物质燃料在高原缺氧环境下对发动机性能和排放的影响,在一台卧式双缸柴油机上分别燃用柴油、乙醇柴油E10(含10%体积分数的乙醇和90%体积分数的柴油)及生物柴油-乙醇-柴油B10E10(含10%体积分数的生物柴油,10%体积分数的乙醇和80%体积分数的柴油)3种燃料进行了对比试验。试验结果表明,在不对柴油机做任何调整的情况下,分别燃用E10和B10E10 2种含氧生物质混合燃料后,柴油机动力性下降,外特性转矩平均下降幅度分别达到4.24%和5.49%;当量燃油消耗率基本低于柴油,经济性有所改善。燃用含氧生物质燃料后,柴油机的经济性变化情况除了与燃料本身的属性相关,还与转速和负荷相关。燃用E10混合燃料后,柴油机的一氧化碳(CO)排放在低负荷时高于柴油,高负荷时低于柴油;碳氢化合物(HC)排放高于柴油水平,升高幅度范围达4.9%~27.4%;氮氧化物(NOX)排放在低负荷时低于柴油,高负荷时趋于柴油水平。燃用B10E10混合燃料后,一氧化碳(CO)和碳氢化合物(HC)排放在低负荷时都趋于柴油水平,高负荷时都低于柴油水平;氮氧化物(NOX)排放在低负荷时低于柴油,高负荷时高于柴油水平。柴油机在燃用E10和B10E10 2种混合燃料后,碳烟排放均低于柴油水平。柴油机燃用B10E10混合燃料后的碳氢化合物(HC)排放,碳烟排放以及低负荷时的一氧化碳(CO)排放均低于E10,氮氧化物(NOX)排放基本高于E10。与E10燃料相比,B10E10混合燃料在柴油机的一氧化碳(CO)和碳氢化合物(HC)以及碳烟排放方面具有更好的改善效果;但是动力性下降幅度较大,氮氧化物(NOX)排放增加。该研究可为含氧生物质燃料在高原缺氧地区的应用提供参考。     

High-yield preparation of wax esters via lipase-catalyzed esterification using fatty acids and alcohols from crambe and camelina oils

Fatty acids obtained from seed oils of crambe (Crambe abyssinica) and camelina (Camelina sativa) via alkaline saponification or steam splitting were esterified using lipases as biocatalysts with oleyl alcohol and the alcohols derived from crambe and camelina oils via hydrogenolysis of their methyl esters. Long-chain wax esters were thus obtained in high yields when Novozym 435 (immobilized lipase B from Candida antarctica) and papaya (Carica papaya) latex lipase were used as biocatalysts and vacuum was applied to remove the water formed. The highest conversions to wax esters were obtained with Novozym 435 (> or =95%) after 4-6 h of reaction, whereas with papaya latex lipase such a high degree of conversion was attained after 24 h. Products obtained from stoichiometric amounts of substrates were almost exclusively (>95%) composed of wax esters having compositions approaching that of jojoba (Simmondsia chinensis) oil, especially when crambe fatty acids in combination with camelina alcohols or camelina fatty acids in combination with crambe alcohols were used as substrates.     

Extraction of grape seed oil using compressed carbon dioxide and propane: extraction yields and characterization of free glycerol compounds

The main objective of this work was to compare the extraction of grape seed oil with compressed carbon dioxide and propane on the extraction yields and chemical characteristics of free glycerol compounds. The experiments were performed in a laboratory scale unit in the temperature range of 30 to 60 degrees C and pressures from 60 to 254 bar. The results showed that propane is a more suitable solvent for grape seed oil extraction than carbon dioxide, as higher extractions yields and a very fast kinetic of extraction were achieved with this solvent. In relation to compressed carbon dioxide extractions, both temperature and density presented a very pronounced and positive effect on the extraction yield. The oils extracted were analyzed qualitatively and quantitatively with regard to the free glycerol compounds, mainly fatty acids, ethyl, and methyl esters. The results showed that these compounds are present in low concentration in vegetable oil (<3%) and that, in general, samples extracted with propane present a smaller amount of peaks of free glycerol compounds in the oil than samples extracted with carbon dioxide.     

尿素包接法预浓缩鱼油生理活性组分的研究

为了提高鱼油中生理活性组分ＥＰＡ和ＤＨＡ的含量，以鱼油乙酯为原料，将其与饱和的尿素－乙醇溶液进行包合作用，而使鱼油中的饱和脂肪酸成结晶析出，以达到预浓缩的目的。随着尿素与鱼油乙酯摩尔比的增加，或结晶温度的降低，容易获得ＥＰＡ和ＤＨＡ含量在７０％以上的制品。     

Determination of esters of fatty acids with low molecular weight alcohols in olive oils

A simple and precise analytical method was developed for the simultaneous determination of squalene and methyl, ethyl, propyl, and butyl esters of fatty acids present in olive and olive pomace oils. A fraction containing squalene and fatty acid alkyl esters was isolated from the oil by solid phase extraction on silica gel cartridges and quantitatively analyzed by gas chromatography. A modification of the procedure allowed the isolation of squalene and esters separately. Repeatability and recovery of the method were good. The method was applied to extra and lampant virgin olive oil categories and also to oils obtained from olive pomace by second centrifugation and solvent extraction. Extra virgin olive oils contained low amounts of fatty acid methyl and ethyl esters, while oils obtained from altered olive or olive pomace showed high concentrations of fatty acid alkyl esters, mainly ethyl esters. Correlation between oil acidity and ethyl esters concentration was poor.     

Biodegradability Studies of Certain Wood Preservatives in Groundwater as Determined by the Respirometric Bod Oxitop Method

This study focuses on the biodegradability measurements of tall oil-based wood preservatives and their raw materials in groundwater as determined by the respirometric BOD OxiTop method. Certain substances were also analyzed in standard conditions described by OECD 301 F. Results show that creosote oil, a traditional wood preservative, does not biodegrade at all in groundwater over a period of 28 days, while tall oil and linseed oil biodegrade to some degree (13.4% and 14.8%, respectively). On the other hand, degrees of biodegradation of linseed oil, tall oil and creosote oil in the extra mineral and microbe including conditions described by OECD 301 F were 72.9%, 54.3% and 24.9% after 28 days, respectively. Studied raw materials of tall oil-based wood preservative production biodegrade to some degree in groundwater (variability from 11.9% to 18%) and quite effectively in OECD 301 F test (variability from 39% to 71.7%) over a period of 28 days. Abiotic degradation may also be significant with the studied substances.     

Application of ethyl esters and d3-methyl esters as internal standards for the gas chromatographic quantification of transesterified fatty acid methyl esters in food

Ethyl esters (FAEE) and trideuterium-labeled methyl esters (d3-FAME) of fatty acids were prepared and investigated regarding their suitability as internal standards (IS) for the determination of fatty acids as methyl esters (FAME). On CP-Sil 88, ethyl esters of odd-numbered fatty acids eluted approximately 0.5 min after the respective FAME, and only coelutions with minor FAME were observed. Depending on the problem, one or even many FAEE can be added as IS for the quantification of FAME by both GC-FID and GC-MS. By contrast, d3-FAME coeluted with FAME on the polar GC column, and the use of the former as IS requires application of GC-MS. In the SIM mode, m/z 77 and 90 are suggested for d3-methyl esters of saturated fatty acids, whereas m/z 88 and 101 are recommended for ethyl esters of saturated fatty acids. These m/z values give either no or very low response for FAME and can thus be used for the analysis of FAME in food by GC-MS in the SIM mode. Fatty acids in sunflower oil and mozzarella cheese were quantified using five saturated FAEE as IS. Gravimetric studies showed that the transesterification procedure could be carried out without of loss of fatty acids. GC-EI/MS full scan analysis was suitable for the quantitative determination of all unsaturated fatty acids in both food samples, whereas GC-EI/MS in the SIM mode was particularly valuable for quantifying minor fatty acids. The novel GC-EI/MS/SIM method using fatty acid ethyl esters as internal standards can be used to quantify individual fatty acids only, that is, without determination of all fatty acids (the common 100% method), although this is present. This was demonstrated by the exclusive quantification of selected fatty acids including methyl-branched fatty acids, erucic acid (18:1n-9trans), and polyunsaturated fatty acids in cod liver oil and goat's milk fat.     

Steryl and stanyl esters of fatty acids by solvent-free esterification and transesterification in vacuo using lipases from Rhizomucor miehei, Candida antarctica, and Carica papaya.

Sitostanol has been converted in high to near-quantitative extent to the corresponding long-chain acyl esters via esterification with oleic acid or transesterification with methyl oleate or trioleoylglycerol using immobilized lipases from Rhizomucor miehei (Lipozyme IM) and Candida antarctica (lipase B, Novozym 435) as biocatalysts in vacuo (20-40 mbar) at 80 degrees C, whereas the conversion was markedly lower at 60 and 40 degrees C. Corresponding conversions observed with papaya (Carica papaya) latex lipase were generally lower. High conversion rates observed in transesterification of sitostanol with methyl oleate at 80 degrees C using Lipozyme IM were retained even after 10 repeated uses of the biocatalyst. Saturated sterols such as sitostanol and 5alpha-cholestan-3beta-ol were the preferred substrates as compared to Delta(5)-unsaturated cholesterol in transesterification reactions with methyl oleate using Lipozyme IM. Transesterification of cholesterol with dimethyl 1,8-octanedioate using Lipozyme IM in vacuo yielded methylcholesteryl 1,8-octanedioate (75%) and dicholesteryl 1,8-octanedioate (5%). However, transesterification of cholesterol with diethyl carbonate and that of oleyl alcohol with ethylcholesteryl carbonate, both catalyzed by Lipozyme IM, gave ethylcholesteryl carbonate and oleylcholesteryl carbonate, respectively, in low yield (20%). Moreover, cholesterol was transesterified with ethyl dihydrocinnamate using Lipozyme IM to give cholesteryl dihydrocinnamate in moderate yield (56%), whereas the corresponding reaction of lanosterol gave lanosteryl oleate in low yield (14%).     

Flavor release and rheology behavior of strawberry fatfree stirred yogurt during storage

The influence of storage on the aroma release in headspace and rheological properties in strawberry-flavored fatfree stirred yogurts was determined. Three periods of storage at 10 degrees C were chosen for analysis: 7, 14, and 28 days. The headspace composition was assessed in a flask in static mode. The SPME fiber was carefully chosen, and results are presented in detail (choice and degradation). The flow properties of the final product were measured in order to follow n (flow behavior index) and K (consistency index), and the apparent viscosity was determined (eta in Pa.s). The quantity of flavors in the headspace of products at the 28 days of aging was significantly weaker for methyl 2-methyl butanoate, ethyl hexanoate, and hexyl acetate. The decrease was half of that in comparison with the seventh day. It was supposed that modification in rheological parameters can partly explain these results. Indeed, the apparent viscosity of the products significantly increased during the three times of storage. The composition of the flavored yogurt, proteins, exopolysaccharides, and fruit preparation, seemed to have a great impact on the release of aroma compounds. The aroma compound amount in the headspace decreased when the matrix changed from water to yogurt. With the fruit preparation, the headspace amounts for esters were significantly lower than in water alone, respectively, 23, 27, 29, and 17% less for methyl 2-methylbutanoate, ethyl hexanoate, hexyl acetate, and benzyl acetate. In flavored yogurt, the amount of aroma compounds in the headspace decreased again in comparison with the result obtained with the fruit preparation. Ethyl hexanoate and hexyl acetate presented the higher decreases of 48 and 53%, respectively.     

Screening of the entire USDA castor germplasm collection for oil content and fatty acid composition for optimum biodiesel production

Castor has tremendous potential as a feedstock for biodiesel production. The oil content and fatty acid composition in castor seed are important factors determining the price for production and affecting the key fuel properties of biodiesel. There are 1033 available castor accessions collected or donated from 48 countries worldwide in the USDA germplasm collection. The entire castor collection was screened for oil content and fatty acid composition by nuclear magnetic resonance (NMR) and gas chromatography (GC), respectively. Castor seeds on the average contain 48.2% oil with significant variability ranging from 37.2 to 60.6%. Methyl esters were prepared from castor seed by alkaline transmethylation. GC analysis of methyl esters confirmed that castor oil was composed primarily of eight fatty acids: 1.48% palmitic (C16:0), 1.58% stearic (C18:0), 4.41% oleic (C18:1), 6.42% linoleic (C18:2), 0.68% linolenic (C18:3), 0.45% gadoleic (C20:1), 84.51% ricinoleic (C18:1-1OH), and 0.47% dihydroxystearic (C18:0-2OH) acids. Significant variability in fatty acid composition was detected among castor accessions. Ricinoleic acid (RA) was positively correlated with dihydroxystearic acid (DHSA) but highly negatively correlated with the five other fatty acids except linolenic acid. The results for oil content and fatty acid composition obtained from this study will be useful for end-users to explore castor germplasm for biodiesel production.