Impulse Response Analysis for Adsorption of Ethyl Acetate on Activated Carbon in Supercritical Carbon Dioxide

Abstract

Adsorption equilibria and mass transport properties for ethyl acetate on activated carbon have been evaluated in the presence of supercritical carbon dioxide by means of the impulse response technique. A two-column system, one for dissolving solute and one for adsorption, was used to evaluate the phenomena purely in the adsorption column. The adsorption equilibrium constant was larger for higher temperature and lower pressure. The apparent heat of adsorption calculated from the temperature dependence of the adsorption equilibrium constant was 30–40 kJ/mol. The intraparticle effective diffusivity was larger for higher temperature and lower pressure. The Peclet number that relates to the axial dispersion coefficient was 0.08–0.39. These estimated parameters are in good agreement with those obtained from desorption measurements reported in the literature.     

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。     

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。     

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。     

超临界CO2萃取小麦胚芽油研究

用超临界ＣＯ２萃取技术对小麦胚芽和成品麦胚进行了萃取研究。结果表明,最佳工艺条件为萃取压力２５．０ＭＰａ,萃取温度３２℃,用气楷７．６１ＮＭ＾３ｋｇ．ｈ．所得的麦胚油品质优越,且其中的维生素Ｅ含量比溶剂法,压榨法所得麦油高。本研究为麦胚油的超临界萃取实现工业化生产提供设计参数。     

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。     

超临界二氧化碳萃取亚麻籽油的研究

采用半连续流程 ,以亚麻籽为原料、超临界CO2 为溶剂萃取亚麻籽油。通过对不同操作压力、温度、时间、CO2 流量条件下萃取曲线平衡段的直线拟和得到亚麻籽油在超临界CO2 中的溶解度 ,并回归了Chrastil方程的参数 ,得到计算亚麻籽油在超临界CO2 中的溶解度的方程。将萃取过程考虑为CO2 通过亚麻籽固定床的模型 ,由Stastova提出的传质方程对不同压力、温度、CO2 流量下的萃取过程进行模拟 ,并分析了传质系数在不同操作条件下的变化     

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。     

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。     

Reaction Calorimetry in Supercritical Carbon Dioxide

Summary: Reaction calorimetry is an efficient tool used to obtain kinetic, thermodynamic and safety data. A reaction calorimeter, RC1e‐HP350, developed in collaboration with Mettler‐Toledo GmbH, allows investigating chemical reactions under supercritical conditions. The main technical difference, compared with a classical liquid system, is that the whole reactor volume is occupied by the media. Heat transfer analysis in supercritical carbon dioxide (scCO₂) by the Wilson plot method shows that the behavior of the internal heat transfer coefficient in scCO₂ is the opposite of the one observed for classical liquid. In scCO₂ the lower the temperature (above the critical point) the better the internal heat transfer coefficient. The evolution of scCO₂ thermodynamical and transport properties near the critical point are responsible for this behavior. The dispersion polymerization of methyl methacrylate in scCO₂, with the polydimethylsiloxane monomethacrylate as stabilizer, is used as a model reaction. A polymerization reaction enthalpy of ?56.9 ± 2.2 kJ · mol^?1 is determined, being in good agreement with previously reported data. The results presented illustrate the accuracy of the heat balance model used and emphasize the potential of reaction calorimetry for the promotion of supercritical fluids technologies.

Technical comparison between liquid and supercritical reaction calorimetry.     

Regeneration of Activated Carbon Loaded with Cyclohexane Using Supercritical Carbon Dioxide: Experimental Results and Modeling

Regeneration of granular activated carbon loaded with cyclohexane by supercritical carbon dioxide was investigated at varying temperatures and pressures. Cyclohexane concentration‐time profiles were measured by means of a supercritical extraction apparatus coupled with an online GC analyzer. The maximum yield of regeneration was 68 % at 55 °C and 140 bar. A mathematical model was proposed which agreed well with the experimental data. Both the Toth and the Langmuir‐Freundlich isotherms were used as adsorption isotherms under equilibrium condition. The mathematical model for activated carbon regeneration was able to adjust the experimental data with relative absolute average deviations of about 4 % and 3.25 %, respectively, for the Toth and the Langmuir‐Freundlich isotherms.     

超临界二氧化碳萃取器萃取分离香茅油

本文介绍了利用现有１５０Ｌ高压釜（压力２０ＭＰａ）改造的超临界二氧化碳萃取器萃取分离香茅油,探讨了压力、温度、时间对萃取分离效果的影响。结果表明,采用超临界二氧化碳萃取器萃取分离香茅油时应选择一个适宜的压力、温度和萃取时间,产品的色、香味、纯度均优于常规的减压蒸馏法。     

超临界CO2-GAS重结晶HMX过程温度对晶体形貌的影响

研究了以丙酮为溶剂的超临界 CO2 - GAS重结晶制细过程温度对 HMX晶型的影响 ,结果表明 :超临界 CO2 - GAS重结晶 HMX过程与常规的重结晶过程相似 ,温度对 HMX晶型起控制作用 ,而对颗粒尺寸影响不大 ;当局部操作温度大于 5 0℃时 ,结晶颗粒中会有α型 HMX生成 ;当整体温度大于 6 0℃时 ,产品中α型 HMX占主要部分。本文就 GAS重结晶过程温度对 HMX晶型影响的机理进行了探讨 ,认为流体压缩和结晶放热引起的局部过热是产生α型 HMX的主要原因     

超临界二氧化碳萃取在石油工业中的应用探究

随着化工工程的发展,超临界技术得以发展并被广泛的应用到了各个领域之中,尤其是石油化工行业。二氧化碳、乙醇、丙烯等气体都可作为流体萃取的溶剂,而在石油工业中,二氧化碳萃取具有独特的优势。对以二氧化碳为溶剂的超临界流体萃取技术在石油工业中的应用情况进行分析与探究。     

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。     

超临界二氧化碳萃取在石油工业中的应用

近年来,超临界二氧化碳萃取技术作为分析化学中一种新兴技术,迅速显示了其特有的效果和广泛的运用前景。文章介绍了超临界二氧化碳萃取的原理和特性,重点阐述其在油气开采和石油炼制研究领域的进展状况,并指出了该技术的发展方向。     

超临界二氧化碳中的不饱和聚酯树脂固化反应

本文研究了超临界二氧化碳对不饱和聚酯树脂固化反应的影响。结果表明超临界二氧化碳能够使不饱和聚酯树脂体系的固体时间有明显的缩短,达到原来固体时间的53.8%。随着超临界二氧化碳的加入,双键反应率有明显降低,但是双键反应率并没有随着压力的升高继续减小。