Chromatographic Analysis of Limonene and Linalool on Silica Gel in Supercritical Carbon Dioxide

ABSTRACT

Adsorption behavior of limonene and linalool, which are respectively the principal constituents of terpene and oxygenated compounds in citrus oil, on silica gel in the presence of supercritical carbon dioxide was analyzed by the tracer response method. In this study a two-column system was used to eliminate the effect of nonideal behavior at the sample injection. Adsorption equilibria and mass transport properties were evaluated by means of the moment method at pressures of 8.8–23.5 MPa and temperatures of 313–333 K. The adsorption equilibrium constant was larger for higher temperature and lower pressure when linalool was selectively adsorbed on silica gel. The apparent heat of adsorption ranged from –20 to 230 kj/mol. The Peclet number and the ratio of intraparticle effective diffusivity to molecular diffusivity were 0.013–0.257 and 0.002–0.716, respectively.     

超临界二氧化碳化学

本文简要介绍了在超临界条件下，二氧化碳化学的新进展，开发研究动向及其发展趋势。     

超临界CO2萃取丁香花蕾的工艺研究及对萃取物的GC—MS分析

本文应用超临界二氧化碳技术 ,研究了丁香花蕾的最佳萃取工艺。结合温度、压力、堆积密度、CO2 流量等因素对丁香花蕾提取物的萃出率的影响 ,采用四因素三水平的正交设计 ,得出丁香花蕾油萃取的最佳工艺条件为 :压力30MPa ,温度 4 5℃ ,CO2 流量 10L/h ,低堆积密度。作者还对萃取出的丁香花蕾油进行了GC—MS成分分析     

超临界流体色谱法测定固体在二氧化碳中的溶解度

开发了一种测定超临界二氧化碳中大分子溶质的溶解度的方法。这一方法将微型超微界流体萃取直接与超临界色谱相耦合，超临界流体色谱采用ＦＩＤ作为检测器。实验中两者具有同一压力、温度及同样的ＣＯ２流速度。     

超临界二氧化碳分离乙醇水溶液的模拟计算

使用PR状态方程结合Hurou和Vidal提出的局部组成混合规则,较好地预测了CO_2-C_2H_5OH-H_2O三元体系的汽液平衡数据。在此基础上,模拟计算了超临界CO_2分离乙醇水溶液的过程。对萃取塔的特点和工艺条件作了详细的讨论。     

超临界二氧化碳萃取蛋黄油实验研究

介绍了超临界二氧化碳萃取技术提取蛋黄洫的工作原理及工艺流程。设计了正交实验.考察萃取压力、萃取温度、萃取时间等参数对萃取率的影响,确定了最佳工艺条件。     

肉豆蔻超临界二氧化碳萃取工艺及其精油的GC-MS分析研究

本文应用超临界CO2 萃取技术 ,研究了肉豆蔻精油及树脂的提取工艺及精油的GC -MS成分分析。结合温度、压力、堆积密度、CO2 流量等因素对肉豆蔻精油和树脂的萃出率的影响 ,采用四因素三水平的正交设计 ,得出肉豆蔻精油及树脂的最佳萃取工艺条件为 :温度 30℃、压力 2 5MPa、CO2 流量 15L/h、堆积密度 0 .5 1± 0 .0 2g/L。     

Supercritical fluid extraction of lipids from spent coffee grounds

Supercritical fluid extraction of lipids from spent coffee grounds was studied in this work. Extraction experiments were carried out with supercritical carbon dioxide at different pressure and temperature conditions to study the influence of those process parameters on the extraction rate and oil composition. Supercritical carbon dioxide extracted up to 85% of the total amount of oil of spent coffee grounds after 3 h of extraction (corresponding to a maximum yield of 15.4 g_oil/100 g_{dry spent coffee}). The fatty acid composition of the extracted oil showed the presence of fatty acids of C14, C16, C18, and C20 carbon chains. Palmitic (C16:0) and linoleic (C18:2) acids were the major fatty acids and comprise about 35% each of the total fatty acid content of the oil. A soxhlet extraction with n-hexane was done for comparison resulting in a maximum yield of oil of 18.3 g_oil/100 g_{dry spent coffee}. Finally, a diffusional model that takes into account the properties of the substrate, the solute partition between the solid and the supercritical phase, and the mass transfer coefficient and axial dispersion in the fluid phase was applied to this system and a good agreement with experimental results was obtained.     

超临界二氧化碳发泡聚苯硫醚研究

采用超临界二氧化碳间歇批处理成型方法成功制备了PPS泡沫材料,同时对所得发泡制品的形态、结晶性能和动态力学性能进行分析,发现在CO2浸泡过程中PPS发生了压力诱导结晶.在温度为80℃,压力为20 MPa情况下,在CO2中浸泡2h的PPS样本可以发泡,而浸泡时间4h和8h的PPS由于结晶度较高不能发泡,为进一步探究该工艺成型发泡PPS奠定了理论基础.     

活性炭纤维对水溶液中醋酸丁酯的吸附性能研究

研究了以活性炭纤维为吸附剂从水溶液中吸附醋酸丁酯的吸附静力学、动力学规律及动态吸附特性。实验表明，活性炭纤维对醋酸丁酯的吸附量较大，吸附速度快，动态吸附、脱附性能好。该方法可行，具有一定的实用价值。     

岩蔷薇超临界二氧化碳萃取研究

采用超临界二氧化碳萃取技术 ,研究了岩蔷薇的萃取工艺。探讨了温度、压力、时间及CO2 流量等因素对萃取物得率的影响 ,采用四因素四水平的正交设计 ,得出超临界二氧化碳萃取最佳工艺条件为 :压力 2 8MPa、温度 40℃、时间 3h、流量 3 0L/h ,萃取物得率为 6.6%。产品质量优于有机溶剂萃取法。     

Bioactive Components of Commercial and Supercritical Carbon Dioxide Processed Wheat Germ Oil

Wheat germ oil (WGO) is a specialty product with a very high nutritional value. The chemical composition of both commercial and pilot scale supercritical carbon dioxide (SC-CO₂) processed WGO was examined. This study showed that methods used for oil extraction and refining did not have a significant effect on the fatty acid composition of the oil. SC-CO₂ extracted oil had a higher tocopherol content than that of commercially hexane extracted oil. The phospholipid content of the SC-CO₂ extracted oil was very low indicating that the SC-CO₂ extraction method could eliminate the degumming step from edible oil refining processes. Although the conventional chemical oil refining technique reduced the tocopherol content of the WGO, it was possible to concentrate tocopherols in WGO by using physical refining methods such as molecular distillation. Published with approval of the Director, Oklahoma Agricultural Experiment Station.     

超临界CO2提取金银花浸膏

本文用超临界ＣＯ２技术从干燥保存的金银花中提取挥发性香料成分。结果表明,用超临界ＣＯ２提取的金银花浸膏具接近原料的特征清香,提取率高;提取挥发油后的金银花仍可作为提取氯原酸的药材。     

活性炭纤维在吸附领域的应用

活性炭纤维是一种新型高效吸附材料。本文阐述了活性炭纤维的结构与吸附性能间的关系，并介绍了它在吸附领域的应用。     

Adsorption of SO2 on Activated Carbon for Low Gas Concentrations

Adsorption experiments of SO₂ on activated carbon has been carried out for low concentrations (about 100 ppm) at room temperature (15 to 33 °C) with varying humidity in the air. The breakthrough curves show that at high relative humidity or relative higher SO₂ concentration, the load capacity increases with respect to temperature. The humidity of the air is also of benefit to the load capacity of SO₂. When an adsorption process is interrupted and the activated carbon is kept closed for a while, the SO₂ concentration at the exit of a fixed‐bed adsorber is similar to that of the fresh activated carbon and begins at a very low value. It appears that the sorption potential has been refreshed after the storage period. Analysis of desorption experiments by simultaneous thermal analysis combined with mass spectrometry (MS) after loading, shows that the physisorbed SO₂ and H₂O are desorbed at low temperatures. At higher temperatures, the MS peak of SO₂ and H₂O occur at the same time. Compared with desorption immediately after loading, after one day, the desorption peak due to the physisorbed SO₂ disappears. From this, it can be concluded that the refreshment of the loading capacity of the activated carbon after storage is mainly due to a change in the nature of the SO₂ from a physisorbed state to a chemisorbed form. The same mechanism leads to a continuous refreshment of the sorption potential by means of a chemical reaction during the adsorption process.     

超临界二氧化碳流体及其主要应用

综述了超临界流体特性、超临界流体的应用及超临界萃取技术。介绍国内外研究的现状，简述超临界技术的发展方向。     

乙醛缩合法制乙酸乙酯的研究

乙醛缩合制乙酸乙酯,转化率达99．5％,选择性达99．5％以上;缩合反应采用两个串联反应器,反应停留时间2小时,反应温度-2—6．5℃;催化剂具有较好的稳定性,存放22天后再使用对实验结果没有明显影响;反应液中催化剂加水分解,蒸发得到的有机组分没有明显变化。     

Evaluation of Degradation and Adsorption of Activated Carbon Fiber Cloth Loaded with Titanium Dioxide

This study combines active carbon fiber cloth (ACFC) with the photocatalyst of titanium dioxide (TiO₂). The proposed method mainly depends on the adsorption effect to effectively catch the adsorbent and then further decompose the surface of the photocatalyst so that the original adsorption site of the active carbon can be emptied. In this way, the absorption site can regain the capability of catching the adsorbent and prevent saturation of the ACFC, hence, extending the service life. The findings of this study show that TiO₂/ACFC possesses good photocatalytic adsorption capability. The same results are observed after several rounds of testing.     

超临界二氧化碳萃取低挥发性液体混合物的相平衡

在半连续式实验设备中分别测定了苯甲醇－２－苯乙醇和苯甲酸酯－苯甲醇的等摩尔混合物与超临界ＣＯ２三元系相平衡数据。实验温度分别为３０８．２Ｋ和３１８．２Ｋ，压力范围为８～２０ＭＰａ。实验结果表明：对第一个三元系，两种液体在超临界ＣＯ２中的溶解度与ＣＯ２在液相中溶解行为密切相关；对第二个三元系，较高压力下，超临界流体相中苯甲酸甲酯浓度突然增大，而苯甲醇浓度变化不明显。通过引入考虑分子体积差别的二元作用参数，用Ｐｅｎｇ－Ｒｏｂｉｎｓｏｎ方程对气液平衡数据进行了关联。