超临界CO2流体萃取的应用进展

超临界CO2流体萃取技术已成为一种新兴分离技术,具有操作简单、快速、效率高、无毒、无污染等优点使其广泛应用于各个领域。文章主要介绍了超临界CO2流体萃取技术的原理及优点,综述了近年来超临界流体萃取技术在食品工业、天然香料工业及中草药开发中的应用,并进行了展望,指出了存在的问题和今后发展的趋势。     

夹带剂对超临界CO2萃取过程的影响

超临界CO2 萃取技术是近年来兴起的一种高新物质分离精制技术 ,但其本身还存在着一些问题 ,如操作压力大、萃取时间长、对设备的要求较高、能耗相对也较大、提取能力小、萃取率有待进一步提高 ,从而限制了其应用领域的进一步拓展和大范围工业化生产的转化。采用夹带剂对超临界萃取过程进行强化 ,可有效提高萃取得率 ,降低操作压力等 ,因而成为人们研究的一个新方向 ,也将对超临界流体萃取技术产生重要的影响。本文就夹带剂对超临界CO2 萃取过程的影响及应用进行了论述 ,并提出了所存在的问题和研究方向。     

温度压力对超临界CO2萃取香兰素的影响

系统地研究超临界CO2 流体技术从香草兰中萃取芳香组分的工艺条件 ,探索工业条件下萃取压力与温度、分离压力与温度以及萃取时间等因素对芳香组分中香兰素含量的影响 ,确定出从香草兰提取香兰素的最佳工艺条件为 :萃取压力35MPa ,萃取温度 4 5℃ ,分离 (Ⅰ )压力 16MPa ,分离 (Ⅰ )温度 4 0℃ ,分离 (Ⅱ )压力 6MPa ,分离 (Ⅱ )温度 4 0℃ ,萃取时间15 0min。     

Continuous extraction of glycerol acetates from their mixture using supercritical carbon dioxide

Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixture of triacetin, diacetin, and monoacetin with a molar ratio of 1:2:1. The extraction was carried out in two stages. In the first stage, a central composite design was used to optimize the four variables of pressure, temperature, liquid CO₂ flow rate, and extraction time at three levels using a semi-continuous, supercritical carbon dioxide extraction setup. The composition of the extract under the predicted optimum conditions (i.e., 109 bar, 56 °C, 0.86 mL min⁻¹, and 61 min) was about 69% triacetin accompanied by only 30% diacetin and no detectable monoacetin. In the second stage, the effect of the two factors, pressure (100, 109, and 140 bar) and liquid CO₂ flow rates of 0.86 and 1.5 mL min⁻¹ measured at average laboratory temperature (27 °C) and pressure (0.89 bar), were studied using a continuous, supercritical carbon dioxide fractionation setup equipped with a glass-bead packed column kept under a thermal gradient of 56-70 °C. The experimental design was organized as a 3 × 2 general factorial design. Under the best conditions (i.e., 140 bar and 1.5 mL min⁻¹), the extraction yield of triacetin and diacetin were 41.8 and 3.0%, respectively, without any detectable monoacetin as verified by GC-FID.     

广西灵香草提取物的化学成分研究及香气评价

目的 :研究广西金秀灵香草提取物的化学成分及香气。方法 :采用超临界CO2 萃取法和溶剂法提取的广西灵香草提取物 ,用气相色谱 /质谱进行分离测定 ,结合计算机检索技术对分离的化合物进行结构鉴定 ,应用色谱峰归一化法确定各成分的相对含量。结果 :超临界CO2 萃取灵香草提取物得率 1.5 % ,鉴定出 2 7个化学成分 ,溶剂法得率 1.2 % ,鉴定出 2 0个化学成分 ;经评定 ,超临界CO2 萃取法得到的提取物气味更接近灵香草天然香气。结论 :用超临界CO2 萃取法可以生产出最接近自然香气的天然香料     

超临界CO2萃取菊花油的实验研究

用超临界CO2 萃取技术对菊花油进行了萃取试验 ,考察了二氧化碳用量 ( 1 0～ 35kg/h)、萃取压力 ( 1 0～ 5 0MPa)、温度 ( 2 0～ 5 0℃ )等对萃取得率的影响 ,同时考虑设备投资对萃取过程的影响 ,得出了超临界二氧化碳萃取菊花油的最佳工艺条件 :萃取压力 30～ 35MPa,操作温度 2 0～ 4 0℃ ,CO2 的流量选择为 2 0～ 2 5kg/h。     

超临界CO2流体萃取技术在食品工业中的新应用

综述了高新技术CO2超临界流体萃取技术及其在食品工业中的最新应用情况。     

超临界CO2萃取技术在天然香料工业中的应用与研究进展

分析了我国天然香料工业发展的形势及其应用新技术的必要性 ,论述了超临界CO2 萃取技术在天然香料开发中应用的现状及优越性 ,提出了应用超临界CO2 萃取技术进行天然香料开发的对策。     

Control of molecular weight distribution of petroleum pitches via multistage supercritical extraction

Packed-column supercritical extraction (SCE), followed by low-pressure gas stripping, was used to produce a dimer-rich pitch fraction from an oligomeric petroleum pitch, Marathon M-50, of broad molecular weight distribution (MWD). Both solvent-to-pitch ratios (S/P) >5 and a positive retrograde temperature gradient of 380-330 °C at 70 bar were found to reduce significantly the amount of trimer+ oligomers in the overhead product from the SCE column. This monomer- and dimer-rich overhead was subsequently stripped of monomer with gaseous toluene in a second packed column at 380 °C and 1.5 bar to obtain an 80+ mol% dimer product with an overall yield, based on the original feed, of 30%. To our knowledge, this is the first reported fractionation of a dimer-rich cut from a petroleum pitch with a demonstrably low level of both lower and higher mol wt impurities.     

超临界CO_2萃取结合柱色谱分离萝芙木生物碱

用超临界CO2萃取技术,设计了4因素3水平正交实验,研究从海南催吐萝芙木中提取利血平生物碱的最佳工艺。最佳提取条件为:萃取压力35 MPa,萃取温度60℃,夹带剂为100 g样品用25 mL乙醇,萃取时间2 h。用高效液相色谱法对萃取产物中的利血平含量进行了测定。将萃取所得产物用硅胶柱色谱进一步分离提纯,得到了质量分数为99.8%的利血平针状结晶。     

成型工艺对超临界CO_2发泡PP结构与性能的影响

采用自制超临界流体反应釜装置,以超临界CO_2作为物理发泡剂,进行聚丙烯(PP)材料的发泡试验研究。探讨了超临界CO_2发泡PP时的发泡温度、发泡压力和泄压速率对PP发泡材料的宏观性能及泡孔结构的影响。结果表明,发泡温度为135℃时,发泡材料的表观密度最小,为0.096 g/cm3;发泡压力为12 MPa时,发泡材料的表观密度最小,为0.075 g/cm~3,当发泡压力继续上升时,PP发泡材料的表观密度有所上升但泡孔直径开始下降;泄压速率为2 MPa/s时,发泡材料的表观密度最小,为0.196 g/cm~3,泡孔的平均直径最大。     

Axial mixing and mass transfer in a vibrating perforated plate extraction column

The axial mixing and countercurrent mass transfer characteristics of a 5 cm diameter extraction column agitated by vibrating perforated Teflon plates have been investigated. The dispersed phase was an organic liquid (usually kerosene) and the continuous phase was water. Axial mixing was measured in both phases using pulse tracer techniques; in the continuous phase the axial mixing was estimated to have a significant effect on mass transfer, but axial mixing in the dispersed phase had a negligible effect. Mass transfer was measured for several different solutes; n-butyric acid, benzoic acid and phenol. The overall heights of a transfer unit (cont. phase) were in the order of 10-20 cm for the organic-acids but higher for transfer of phenol from very dilute solutions. The characteristics of the vibrating plate column have been compared with those of other types of extractor and suggestions are made for further development.     

Steady state hydrodynamics and mass transfer characteristics of a karr extraction column

The steady state hydrodynamics of the holdup in a 15 cm column agree quite well with mechanistic predictions at conditions approaching flooding. In the presence of mass transfer (acetic acid from the dispersed kerosene phase to the continuous water phase), the holdup data below flooding are not well predicted by the model due to enhanced droplet coalescence. The prediction of holdup at flooding is a function of the ratio of the flow rates but is independent of the physicochemical properties of the extraction system, and therefore can be used to estimate the flooding holdup regardless of the occurrence of mass transfer. In the second part of the paper, steady state mass transfer characteristics of the column were also simulated using a mechanistic model. Despite the difficulty of estimating parameters such as the mass transfer coefficient, the model curves could be arbitrarily adjusted to fit observed exit concentrations. These steady state results provide useful insights on the non-linearity of the system from a control viewpoint.