夹带剂及其对超临界CO_2萃取效能的影响

Modifier Effect on the Efficacy of Supercritical CO_2 Extraction

作为高新技术的超临界CO2萃取技术近年来受到极大关注,并广泛推广应用。但也发现超临界CO2萃取技术还存在着:操作压力大、萃取时间长、对设备的要求较高、能耗相对较大、提取容量小、萃取率不够理想等有待提高或改善的问题,而采用夹带剂对超临界萃取过程进行强化,能有效提高萃取得率、降低操作压力等。因此,本文从夹带剂在超临界CO2萃取中的作用原理出发,讨论夹带剂分子特性对超临界CO2萃取效能的影响,也对在夹带剂下超临界CO2萃取存在的问题也作了简要阐述。并总结出夹带剂性质对萃取率的变化规律是:夹带剂的分子极性越大,溶质在超临界CO2中的溶解度越大;夹带剂的相对分子质量或分子体积的增大,其在超临界CO2中的溶解度降低,萃取率减小;易形成氢键的夹带剂分子,能明显提高萃取率;多(混合)组分的夹带剂,对萃取效能的提高更显著。

Supercritical CO2 extraction is a new subject of separation techniques and develops rapidly in recent years becauseof its advantages over conventional extraction methods. However, there are still some problems unsolved with it,such as highoperation pressure,long extraction time,relatively low extraction yield etc., so that it could not be used widely on industrial scale.Since modifier can enhance supercritical CO2 extraction process and be used to solve the problems mentioned above, it becomesa new orientation of research on supercritical CO2 extraction. The effect and principle of the modifiers on the supercriticalCO2extraction were introduced and the impact of the property of modifiers(molecular polarity、molecular weight、molecularphysical volume) on the supercritical CO2 extraction were analyzed in this paper. The profile of extraction yield against property ofthe modified can be summarized:The higher the polarity of the modifier,the higher solubility of solute in supercritical CO2.Increase of molecular and/or molecular physical volume will result-in decrease of solubility of solute in supercritical CO2 andconsequently the decrease of the extraction yield. In case the modifier contains special molecular structure that facilitates theformation of hydrogen bond,the extraction yield will increase.