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1.
分子蒸馏浓缩菜籽油脱臭馏出物中维生素E的研究   总被引:1,自引:0,他引:1  
邵平  姜绍通  郑志  孙培龙 《核农学报》2007,21(6):597-601
菜籽油脱臭馏出物(RODD)中富含天然VE,是浓缩VE的重要原料。RODD直接结晶去除甾醇,并在蒸馏温度473K和压力2.66Pa时分子蒸馏脱除重组分。分子蒸馏馏出液经皂化、盐酸酸化、水洗干燥后作为分子蒸馏浓缩VE原料。当分子蒸馏刮膜转速为150rpm、真空度5.3Pa、蒸馏温度403K、进料速率2.068ml/min时,得到含26.32%VE的产品,VE回收率可达69.23%,轻组分FFA回收率达85%。甲酯化-蒸馏方法在蒸馏温度403K时获得30%纯度的VE。  相似文献   

2.
菜籽油脱臭馏出物中甾醇分离的甲酯化过程优化研究   总被引:2,自引:1,他引:1  
运用中心组合设计,以甾醇得率与纯度为考察指标,对菜籽油脱臭馏出物的甲酯化过程工艺进行了优化研究。通过甾醇回收率的响应曲面分析,考察了甲酯化时间、催化剂浓硫酸量与甲醇/物料比及其交互作用的影响,并建立了其数学回归模型,利用Matlab绘制出响应曲面图,揭示了内在关系。结果表明:甲酯化温度60℃,甲醇/物料比100 mL/(100 g),甲酯化时间1.65 h,催化剂浓硫酸加量4.4%,将甲酯化产物通过结晶与冷冻高速离心,甾醇得到较高纯度与得率,维生素E也得到较好保留。二次重结晶甾醇纯度可以达到95%以上,总得率达到45%以上。  相似文献   

3.
生物柴油的低温流动性主要取决于化学组成。为了量化表征生物柴油组成与其冷滤点的关系,采用气相色谱-质谱与冷滤点分析技术和多元线性回归分析方法,分析了生物柴油的脂肪酸甲酯组成和冷滤点,研究了脂肪酸甲酯组成对冷滤点的影响规律。研究表明:生物柴油主要由14~24个偶数碳原子组成的长链脂肪酸甲酯组成,其中饱和脂肪酸甲酯主要为C14:0~C24:0,不饱和脂肪酸甲酯主要为C16:1~C22:1、C18:2~C20:2和C18:3。120种生物柴油油样中,乌桕梓油生物柴油的冷滤点最低,为-14℃,花生油生物柴油的冷滤点最高,为13℃。生物柴油的脂肪酸甲酯的含量与分布不同,冷滤点差异较大。冷滤点随饱和脂肪酸甲酯含量的增加呈线性升高,且碳链长的较短的增加显著;随不饱和脂肪酸甲酯含量的增加而呈线性降低,且不饱和度高的较低的降低略明显。建立了线性相关性非常显著(R=0.971)的基于组成的冷滤点预测模型。研究结果为不同环境下生物柴油的推广应用提供参考。  相似文献   

4.
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%。  相似文献   

5.
应用短程蒸馏技术提纯胡椒基丁醚   总被引:5,自引:1,他引:4       下载免费PDF全文
应用刮膜式短程蒸馏装置对胡椒基丁醚(piperonyl butoxide, PB)的提纯进行了研究。考察了进料速率、进料温度和蒸发温度等因素对胡椒基丁醚分离效果的影响。通过试验,初步得到了工艺参数的范围:进料温度70~92℃,进料速率50~70 mL/h,脱除轻组分杂质阶段蒸发温度I为90~94℃,脱除重组分杂质阶段蒸发温度II为98~107℃,操作压力0.1 Pa,刮膜转子转速130~150 r/min,得到的胡椒基丁醚产品纯度96%以上,分离过程总得率大于70%,并为今后工艺参数优化奠定了基础。  相似文献   

6.
脂肪酸甲酯生物柴油改善低硫柴油的润滑性能   总被引:1,自引:1,他引:0  
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。  相似文献   

7.
皂脚制备生物柴油的试验研究   总被引:13,自引:4,他引:9  
在食用油生产过程中均会不同程度地产生皂脚(又称油泥),为解决皂脚排放造成的环境污染及资源浪费问题,该文以皂脚为原料进行制备生物柴油的试验分析。提出了皂脚经循环气相酯化—水蒸气蒸馏制备生物柴油的方法和工艺流程,探讨解决制备过程中酯化反应的连续带水和反应快速进行的问题,得到优化工艺参数。试验装置主要由气相酯化反应器、甲醇气化器、粗生物柴油精馏器和油水分离器等组成。研究结果表明,酯化反应温度为(100±5)℃,皂脚质量0.5%~0.8%的硫酸或3%~4%的对甲苯磺酸为催化剂,甲醇蒸气通入速度6 L/min,反应时间90~120 min,生物柴油精馏器的液相温度为160~220℃,气相温度为120~190℃,水蒸气温度为(100±5)℃,水蒸气通入量为5 L/min,能使皂脚制备生物柴油的转化率达99%以上,产品品质指标基本达到美国的ASTM生物柴油标准,并与中国的0#柴油接近。  相似文献   

8.
分子蒸馏工艺参数对高碳脂肪醇提取物精制效果的研究   总被引:8,自引:3,他引:5  
采用分子蒸馏技术进行高碳脂肪醇提取物的精制,试验结果表明,蒸馏压力66.7 Pa,蒸馏温度在160~230℃范围内,随着蒸馏温度升高,馏出物中的二十八烷醇和三十烷醇含量逐渐增加,并在190℃时出现峰值,之后下降;蒸馏温度190℃,蒸馏压力在26.7~266.7 Pa范围内,随着压力的下降,馏出物中的二十八烷醇和三十烷醇含量增加,到133.3 Pa处分别达到最大值。蒸馏温度和压力作为分子蒸馏的关键工艺参数对高碳脂肪醇的精制效果具有显著影响。  相似文献   

9.
为了优化巨尾桉叶精油精制工艺,采用短程分子蒸馏,对初级桉叶精油中1,8-桉叶素和α-蒎烯进行精制,研究不同温度和压力条件下2种物质分离特性。以巨尾桉叶为试验材料,依次采用超临界CO2萃取和分子蒸馏对其进行桉叶油树脂提取和纯化得到初级桉叶精油,采用二因素五水平的响应面优化试验,将馏出物得率、馏出物中1,8-桉叶油素质量分数及α-蒎烯质量分数、馏余物中1,8-桉叶油素质量分数及α-蒎烯质量分数作为试验指标,对分子蒸馏精制桉叶精油工艺进行优化研究。最优纯化工艺条件:以馏出物为目标产物,蒸馏温度38℃,蒸馏压力41 Pa,馏出物中1,8-桉叶油素和α-蒎烯的质量分数分别约为60.80%和31.58%,馏出物的得率为82.06%。分子蒸馏能够对桉叶精油进行有效的纯化精制,桉叶初级精油经过二级分子蒸馏精制后,1,8-桉叶油素和α-蒎烯的质量分数分别提高了77.62%和56.72%。蒸馏温度和蒸馏压力对1,8-桉叶油素质量分数的影响均较α-蒎烯明显,同时,对于1,8-桉叶油素,蒸馏压力的变化对其质量分数的影响较蒸馏温度明显,相反的,对于α-蒎烯,蒸馏温度对其质量分数影响更为显著(P0.05),该研究结果可为分离提纯2种物质提供技术参考。  相似文献   

10.
棉籽油基生物柴油铜片腐蚀特性   总被引:1,自引:0,他引:1  
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。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引:2,自引:2,他引:0  
【目的】以富士(Fuji)、 秦冠(Qinguan)嫁接在平邑甜茶(Malus hupehensis Rehd.)上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水(ZZ)、 低氮正常水(DZ)、 正常氮干旱(ZG)、 低氮干旱(DG)。氮素和水分均设置两个水平,分别为正常氮(6 mmol/L NO-3-N)、 低氮(0.3 mmol/LNO-3-N)、 正常供水(保持盆中砂子相对含水量为饱和含水量的80%~85%)、 干旱处理(保持盆中砂子相对含水量为饱和含水量的60%~65%)。【结果】富士和秦冠的生物量(茎和叶)、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水(ZZ)>低氮正常水(DZ)>正常氮干旱(ZG)>低氮干旱(DG),并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水(ZZ)>低氮正常水(DZ)>正常氮干旱(ZG)>低氮干旱(DG); 氮、 钾元素含量在植株各部位的分布顺序依次是叶>根>茎,磷元素则是根>叶>茎;光合氮素利用效率(PNUE)和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水(DZ)处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱(DG)处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。  相似文献   

12.
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.  相似文献   

13.
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,  相似文献   

14.
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.  相似文献   

15.
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.  相似文献   

16.
李聃枫  朱春梧 《土壤》2020,52(3):561-566
自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。  相似文献   

17.
Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.  相似文献   

18.
Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.  相似文献   

19.
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.  相似文献   

20.
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

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