Comparison of Constituents and Insecticidal Activities of Essential Oil from Artemisia lavandulaefolia by Steam Distillation and Supercritical-CO_2 Fluid Extraction

Essential oil was extracted from Artemisia lavandulaefolia DC.by steam distillation（SD） and supercritical-CO2 fluid extraction（SFE）,respectively.The constituents of the essentil oils extracted with those two methods were analyzed by gas chromatography-mass spectrometry（GC-MS） and insecticidal activities of the essential oils were evaluated,then the results were compared to assess their biological activity.Thirty-one compounds were identified in the essential oil extracted by SD,and its main components were eucalyptol,α,α,4-trimethyl-3-cyclohexene-1-methanol and so on.Twenty-two compounds were identified for the essential oil extracted by SFE,and its main components were cyclodecene,n-hexadecanoic acid and so on.Six chemical compositions were all contained in the essential oils extracted by the two methods,i.e.,eucalyptol,α,α,4-trimethyl-3-cyclohexene-1-methanol,caryophyllene,[3aS-（3aα,3bβ,4β,7α,7aS）]-octahydro-7-methyl-3-methylene-4-（1-methylethyl）-1H-cyclopenta[1,3]cyclopropa-[1,2]benzene,nerolidol and（-）-Spathulenol.The fumigation toxicity of the essential oil obtained by means of SD to the adults of Sitophilus zeamais is significantly higher than that of the essential oil by means of SFE.The contact toxicity of the essential oil obtained by means of SFE to the adults of S.zeamais is higher than that of the essential oil obtained by means of SD,but the difference is not significant.

Characterization of wet microalgal cells pretreated with steam for lipid extraction

Steam pretreatment was employed to disrupt Microalgal cells for lipids extraction.Effects of steam pretreatment on microstructure of microalgal cells were investigated through scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Effect of treatment on lipid extraction was also studied.Microalgal cell walls were distorted after steam pretreatment due to the hydrolysis of organic macromolecules contained in cell wall.Maximum curvature was increased from 1.88×10^(-6) m^(-1) to 1.43×10^(-7) m^(-1) after treatment with the steam at 130℃.The fractal dimension of microalgal cells increased from 1.25 to 1.30 after pretreatment for 15 min,and further increased to 1.47 when the pretreatment time was increased to 60 min.Increased steam pretreatment temperature and time enhanced the hydrolysis of organic macromolecules,and finally destroyed microalgal cell walls at pretreatment temperature of 130℃and pretreatment time of 60 min.Lipid extracted from wet microalgal was significantly increased(2.1-fold)after pretreatment.

Predicting Mass Transfer Extraction with Steam Flow, Applying Boundary-Layer Concepts

Theory and concepts of boundary layer mass transfer is applied to correlate experimental data on extraction of essential oils from vegetable leaves and stems, using steam. From these theory, concepts and experimental data with seven systems, two correlations are developed to predict the Sherwood number and mass transfer coefficient as function of Reynolds and Schmidt numbers. From these equations, the molar flux, the amount of solute extracted, and the yield of extraction is predicted. A steam of higher temperature normally improves the mass transfer and the yield. A method to estimate the enhancement for temperature increase is proposed. The correlations developed are applied to a case with industrial size that was no part of the data for correlation generation. Theory may be applied for industrial applications.

Effect of Three Extraction Methods on the Volatile Component of Illicium verum Hook.f.Analyzed by GC-MS

The physical properties and chemical components of three oil samples extracted from Illicium verum Hook. f. by steam distillation （SD）, solvent extraction （SE） and supercritical fluid extraction （SFE） were compared with one another and analyzed by Gas Chromatography-Mass Spectrometry （GC-MS）. The quality parameters of star anise essential oil from SFE were close to that of those came from SD and SE. Although the extraction yield of star anise by SFE （9.2 %） was close to the value from SE （9.3%）, it was yet higher than that came from SD （8.2%）. For sensory evaluation, however, three oils were significantly different. The odor and taste of the products from SFE and SE were generally more natural and vivid than that came from distilled oil. The volatile compound revealed that significant differences of the composition existed in the distilled oil and the oleoresins prepared by SFE and SE.

Optimization of Steam Explosion Process Condition for Extracting Polysaccharides from Pseudostellaria heterophylla by Response Surface Methodology

【Objective】To optimize the steam explosion process condition for extracting polysaccharides from Pseudostellaria heterophylla.【Method】The effects of steam pressure,pressure-maintaining time and material moisture content on the extraction of polysaccharides from Pseudostellaria heterophylla were studied by response surface methodology based on Box-Behnken design.【Result】The findings showed that each factor could significantly affect the test index,and the optimum condition was as follows:steam pressure 1.50 Mpa,pressuremaintaining time 46 s and material moisture content 46%.Under this condition,the verified experimental value of polysaccharides from Pseudostellaria heterophylla was 39.32%,indicating a relative standard deviation of 2.73%from the predictive value.Meanwhile,scanning electron microcopy(SEM)images showed that the surface physical structure of Pseudostellaria heterophylla was irregularly broken and cracked,which means the physical structure of Pseudostellaria heterophylla was changed and destroyed at the cellular level.【Conclusion】This experiment provides a new approach for the extraction of polysaccharides from Pseudostellaria heterophylla,as well as a reference for the resource utilization of Pseudostellaria heterophylla.

A Comparative Study on Hemp(Cannabis sativa)Essential Oil Extraction Using Traditional and Advanced Techniques

A comparative study of Cannabis sativa(Hemp)essential constituents obtained by using Supercritical Fluid Extraction(SCFE),Steam Distillation(SD)and Hydrodistillation(HD)is presented here.The optimized extraction temperatures were 130,110and 50℃for hydrodistillation,steam distillation and supercritical fluid extraction respectively.The essential oil of C.sativa was analyzed by using Gas chromatography mass spectrometry(GC-MS).A total of 33,30and 31components have been identified in HD,SD and SCFE respectively.Yield of essential oil using SCFE(0.039%)was more than HD(0.025%)and SD(0.035%)extraction respectively.The main component of sesquiterpenes obtained by hydrodistillation at 130℃with their percentages included caryophyllene(40.58%),trans-α-bergamotene(5.41%),humulene(10.97%),cis-β-farnesene(8.53%)and monoterpenes includedα-pinene(2.13%),d-limonene(6.46%),p-cymol(0.65%)and cineole(2.58%)respectively.The main component of sesquiterpenes obtained by SD steam distillation at110℃including caryophyllene(38.60%)trans-α-bergamotene(4.22%),humulene(10.26%),cis-β-farnesene(6.67%)and monoterpenes includedα-pinene(3.21%),d-limonene(7.07%),p-cymol(2.59%)and cineole(3.88%)whereas the more percentages of major components were obtained by SCFE at 50℃included caryophyllene(44.31%),trans-α-bergamotene(6.79%),humulene(11.97%)cis-β-farnesene(9.71%)and monoterpenes includedα-pinene(0.45%),d-limonene(2.13%)p-cymol(0.19%)and cineole(1.38%)respectively.We found yield/efficiency,chemical composition,quality of the essential oils by supercritical fluid extraction superior in terms of modern,green,saving energy and a rapid approach as compared to traditional techniques.

Regeneration of waste activated carbon after extracting gold with steam under microwave heating:Optimization using response surface methodology

The technology that waste activated carbon after extracting gold is regenerated with steam under microwave heating was studied. The influence of the activation temperature, activation duration and steam flow rate on iodine adsorption value and regeneration yield of activated carbon was investigated. The response surface methodology （RSM） technique was utilized to optimize the process conditions. The optimum conditions for the preparation of activated carbon are identified to be activation temperature of 831 ℃, activation duration of 40 min and steam flow rate of 2.67 mL/min. The optimum conditions result in an activated carbon with an iodine number of 1048 mg/g and a yield of 40%, and the BET surface area evaluated using nitrogen adsorption isotherm is 1493 m2/g, with total pore volume of 1.242 cm3/g. And the pore structure of activated carbon regenerated is mainly composed of micropores and a small amount of mesopores.

Extraction Optimization and Composition Analysis of Volatile Oil from Fruit of Alpinia zerumbet

[Objectives] The aim was to determine the optimum process for the extraction of volatile oil from Alpinia zerumbet fruit.[Methods]Steam distillation was used to extract volatile oil from A. zerumbet fruit. Based on the single factor tests,an orthogonal test was designed to explore the effects of solid-liquid ratio,soaking time,extraction time and grinding degree of material on the extraction rate. The composition of volatile oil from A. zerumbet fruit was analyzed using gas chromatography-mass spectrometry( GC-MS),and the relative mass fraction of each component was determined by peak area normalization. [Results] With volatile oil yield as the index,the optimum extraction process was determined: solid to liquid ratio of 1∶ 10,soaking time of 0. 5 h,grinding degree of passing through 24-mesh sieve and extraction time of 5 h. A total of 29 compounds were isolated. Among them,the contents of α-terpinene( 24. 894%),1,8-terpadiene( 15. 527%) andα-pinene( 6. 982%) were relatively high. [Conclusions]The optimized extraction process for volatile oil from A. zerumbet fruit is stable and reasonable. Under the optimum extraction process,the extraction effect of volatile oil from A. zerumbet fruit was the best. The chemical components of volatile oil from A. zerumbet fruit were determined by GC-MS as α-terpinene( 24. 894%),1,8-terpadiene( 15. 527%) and α-pinene( 6. 982%).

配置吸收式热泵的热电联产机组厂级智能运行优化

为提高配置吸收式热泵的热电联产机组的全厂运行经济性,基于案例电厂的运行历史数据,使用滑动窗口法进行数据预处理并提取稳态工况,建立配置吸收式热泵的热电联产机组煤耗预测数学模型。以全厂热电联产机组总煤耗最小为适应度函数,利用粒子群优化算法求解得出配置吸收式热泵的热电机组最佳背压和各台热电机组最佳抽汽量。基于以上研究设计了供热系统智能优化软件,实现供热系统在线监测与优化调节,对各供热单元分别提出优化指导,使机组运行经济性最佳,进而降低整体煤耗。计算结果表明:实行供热系统智能优化策略可为案例电厂供热系统平均每小时节省标准煤约1.81 t,节能效果显著。

不同萃取方法下绿萼梅花蕾挥发性成分的差异研究

2023年3月13日,从浙江省长兴县东方梅园有限公司梅花基地采集绿萼梅花蕾,采用顶空-固相微萃取、水蒸气蒸馏、超临界二氧化碳3种萃取方法,结合气相色谱-质谱联用仪(GC-MS)分析绿萼梅Prunus mume f.viridicalyx花蕾中的挥发性成分,以明确其花蕾中挥发性成分组成、含量及不同萃取方式对挥发性成分萃取效果的影响。结果表明,三种萃取方法获得的绿萼梅花提取物中共鉴定出醛、醇、酮、烯等9类57种化合物,主要挥发性成分是苯甲醛、壬醛、金合欢醇、苯甲酸、α-香树脂醇、D-柠檬烯,其中苯甲醛含量最高。绿萼梅花顶空-固相微萃取物中共鉴定出21种化合物,以醛、醇和酯类化合物为主;水蒸气蒸馏物中共鉴定出30种化合物,以酯、烯、酮等水难溶化合物为主;而超临界二氧化碳提取物中共鉴定出30种化合物,以长链烷、酯类化合物为主。三种提取方法中超临界二氧化碳萃取物中蜡质含量较高,顶空-固相微萃取和水蒸气蒸馏法结合更适合作为植物芳香类挥发物的检测手段。

页岩油藏提高采收率技术现状、瓶颈及对策

介绍了页岩油的储量分布、成因及赋存机理,详细概述了页岩油早期勘探、储层改造及后期提采等不同阶段的开发现状。在此基础上,着重综述了当前国内外页岩油藏提高采收率主体技术的应用现状及进展,深入分析了不同页岩油提采技术的优势与不足,同时给出了针对理论认识、技术及经济壁垒的相应策略,最后从不同角度入手,展望了今后页岩EOR的发展前景。

某600MW机组锅炉主汽出口抽汽方案安全性分析

供热抽汽是形势所趋,本文以某60万千瓦锅炉主汽出口管道最大抽汽量方案进行核算,分别就30%、40%和50%锅炉负荷、在保证发电量不变的基础上,通过壁温计算模型的建立,最终理论计算出三个负荷下最大的理论抽汽量,可为后续供热抽汽改造方案设计提供一些参考。

大蒜挥发油的提取工艺研究

主要对大蒜挥发油的提取工艺进行了研究。研究结果显示:当大蒜量、水量和蒸馏时间均为相同定值时,大蒜粉碎程度好,出油率会增加;当料液比、蒸馏时间和粉碎程度为定值时,大蒜浸泡后,挥发油出油率高;当料液比、蒸馏时间、浸泡时间和粉碎程度为定值时,大蒜去皮与带皮,大蒜挥发油出油率无明显差别,可以带皮提取,省时省力;浸泡时间达到25 h,蒸馏时间可大大缩短。这就为挥发油的大规模生产提供了依据。

BEST小汽轮机带小发电机运行控制策略研究与应用

为了满足火电机组启动运行的灵活性、高效性及经济性,将抽汽背压式汽轮机(BEST)小汽轮机带小发电机系统(简称BEST系统)应用于双机回热系统机组,根据BEST系统及机组启动方式,结合调试调整试验的启动运行历史过程及数据,进行BEST系统在多方式启动及运行的特性分析试验,优化现有控制逻辑,提出BEST小汽轮机带小发电机运行控制策略。避免了在BEST系统启动顺控、变流器启停顺控、BEST小汽轮机与变流器的无扰切换、燃煤机组辅机故障减负荷(RB)及甩负荷工况中BEST系统缺乏相应控制策略的问题,实现了BEST系统全过程无断点的运行控制。优化后BEST系统运行过程中重要参数保持安全稳定,该控制方法对具备BEST系统的同类型机组具有重要参考意义。

野菊花精油提取工艺优化研究

以野菊花为物料,采用水蒸气蒸馏技术提取野菊花精油;以野菊花精油得率为指标,通过响应面试验优化提取工艺。结果表明:最佳提取工艺条件为液料比值17(m L/g),粉碎程度0.250 mm(60目),提取时间5.4 h。经过实验验证,得出野菊花精油得率为0.2499±0.0131%。文章为野菊花精油的进一步研究及相关产品的开发提供了理论依据。

双酶辅助水蒸气蒸馏法提取肉豆蔻精油及其GC-MS成分分析

采用双酶辅助水蒸气蒸馏法提取广西产肉豆蔻的精油,并通过GC-MS对其进行成分分析。正交实验结果表明,最优提取工艺条件为加酶量2%、酶解pH 4.0、酶解温度40℃,在此条件下,肉豆蔻精油的得率为6.50 mL/100 g。利用GC-MS和保留指数法从精油中鉴定出56种化合物,占精油总量的99.71%,主要成分为肉豆蔻醚(16.60%)、甲基丁香酚(14.78%)、桧烯(13.47%)、(+)-柠檬烯(7.29%)、4-萜烯醇(6.75%)、榄香素(6.62%)、γ-松油烯(4.28%)、反式-甲基异丁香酚(3.73%)、β-蒎烯(3.59%)和黄樟素(3.22%)。

抽汽式汽轮机热电解耦控制研究

从汽轮机热电耦合关系入手,分析热电解耦控制原理,建立抽汽机组的数学模型,通过实际计算验证控制方法,并在控制平台搭建解耦控制逻辑组态,得出解耦控制的实现方法,为热电解耦实际工程应用提供参考和支持。

汽爆预处理对油莎豆组分、微观结构及油脂提取率的影响

旨在提高油莎豆油的提取率,对油莎豆进行不同时间的汽爆预处理,探究汽爆预处理对油莎豆的化学组分、微观结构以及油脂提取率的影响。结果显示:汽爆预处理使油莎豆的脂溶物和水溶物含量增加,纤维素、半纤维素和果胶含量减少,木质素含量增加;汽爆预处理使油莎豆细胞壁主要化学键发生断裂或修饰;汽爆(30min)后油莎豆形状发生明显变化,细胞间裂缝变大,细胞结构破损,排列杂乱;汽爆后油莎豆的油脂提取率增至18.41%,比汽爆前(14.58%)提高26.27%。综上,汽爆破壁促进油莎豆油提取的方法是可行的。

不同预处理对荷叶离褶伞水提残渣多糖理化性质及免疫活性的影响

以常规粉碎为对照,分别采用挤压膨化和蒸汽爆破对荷叶离褶伞(Lyophyllum decastes)子实体沸水提取剩余残渣进行预处理后提取多糖,并进行理化性质和免疫活性分析。结果表明:挤压膨化处理所得粗多糖(LCJ)得率和多糖含量分别为7.17%和60.73%,是常规粉碎组(LCW)的1.13和1.08倍;蒸汽爆破处理后提取的粗多糖(LCQ)得率和多糖含量可达15.42%和88.66%,分别是LCW的2.44倍和1.58倍。红外光谱分析3种方式提取所得残渣的粗多糖均具有多糖的特征吸收峰;LCW和LCJ中多糖组分的分子质量分布特征相似,均主要含有4个峰,LCQ多糖组分的分子质量分布变化较大,主要含有3个峰且低分子质量组分(P3)占比增加。三种粗多糖均由葡萄糖、岩藻糖、半乳糖和甘露糖组成,其中以葡萄糖为主,单糖的相对摩尔百分比有差异,LCQ中葡萄糖占比最高(76.22%)。三种处理所得残渣粗多糖均具有较好的增强免疫活性,10μg·mL^(-1)LCQ活性优于LCW和LCJ。

闽楠挥发性组分提取工艺优化及组学分析

为优化闽楠挥发性组分水蒸气蒸馏工艺,并探究闽楠各部位挥发性组分差异。以广东省乐昌市闽楠试验林的叶片、枝条、树干及根系4个部位为试验材料,采用水蒸气蒸馏法,开展单因素试验及正交试验,考察离子溶液浓度、料液比及提取时间3个影响因素对挥发性组分产率的影响,确定最佳工艺参数;用气相色谱-质谱联用(GC-MS)技术测定各部位挥发性组分含量。结果表明:(1)叶片挥发性组分最优提取工艺为NaCl浓度45 g·L^(-1)、料液比1∶6、提取时间5 h,产率为0.056%;检测出110种挥发性组分,含量最高的5种组分为β-瑟林烯、β-桉叶醇、双环大根香叶烯、香橙烯、α-衣兰油烯。(2)枝条挥发性组分最优提取工艺为NaCl浓度45 g·L^(-1)、料液比1∶8、提取时间5 h,产率为0.083%;检测出80种挥发性组分,含量最高的5种组分为愈创醇、乙酸愈创木酯、茅苍术醇、γ-桉叶醇和δ-杜松烯。(3)树干挥发性组分最优提取工艺为NaCl浓度30 g·L^(-1)、料液比1∶8、提取时间5 h,产率为0.323%;检测出64种挥发性组分,含量最高的5种组分为茅苍术醇、γ-杜松烯、愈创醇、γ-桉叶醇和马鞭草烯酮。(4)根系挥发性组分最优提取工艺为NaCl浓度30 g·L^(-1)、料液比1∶9、提取时间5 h,产率为1.025%;检测出69种挥发性组分,含量最高的5种组分为茅苍术醇、γ-杜松烯、愈创醇、γ-桉叶醇和马鞭草烯酮。(5)闽楠各部位挥发性组分以萜类和醇类物质居多,占总含量80%以上,4个部位的共有成分仅15种,叶片与其他3个部位的成分差异较大。