溶质在超临界流体中扩散系数及其构效关系研究

Diffusion coefficient is useful in design, scale-up and optimization of reactors and separators for supercritical fluid extraction or chromatography. Therefore, it is very important to investigate the diffusion coefficient in supercritical fluids. Current studies are mainly limited to binary systems and deal with the determination of diffusion coefficient data. The effects of intermolecular interaction and steric configuration on the diffusion coefficients have not been illustrated yet.Therefore ,in this work ,a series of aromatic compounds and flavonoids compounds are chosen according to their molecular structure, and the diffusion coefficients of the solutes in supercritical CO2 and ethane with different modifiers are measured by capillary peak broadening method,respectively.The relationship between the molecular structure of solutes and diffusion coefficients as well as the relationship between intermolecular interaction and diffusion coefficients will be investigated in depth by means of a combination of infrared spectroscopy and molecular dynamics simulation,in order to obtain better microscopic understanding the mechanism of mass transfer.The model which not only have good predictive results but also can correlate the the diffusion coefficient with the mocular structure will be expected established.This work will to lay a solid theoretical and practical basis for the application of supercritical fluid technology in industry.

溶质在超临界流体中的扩散系数是超临界萃取及分离装置的工程放大、流程设计以及工艺优化所必需的基础数据。因此，对扩散系数的研究十分重要。现有研究多集中于二元体系，且仅限于数据测定，对于分子间作用力及溶质构型对扩散系数的影响规律尚未得到系统阐明。为此，本课题根据溶质的分子构型选择一系列芳香化合物及黄酮类化合物作为研究对象，测定其在超临界CO2、超临界乙烷、以及夹带不同改性剂的超临界流体中无限稀释扩散系数；采用红外光谱和分子模拟相结合的研究手段深入探讨溶质在超临界流体中扩散系数的构效关系及扩散系数与分子间相互作用力相关性，从微观分子水平探究传递作用机制；在此基础上，构建关联溶质扩散系数与溶质分子结构特性的定量构效关系模型，为超临界流体技术在相关工业领域中的应用奠定坚实的理论和实践基础。

溶质在超临界流体中的扩散系数是超临界萃取及分离装置的工程放大、流程设计以及工艺优化所必需的基础数据。 因此，本项目以Taylor 毛细管峰扩展法以及调整的色谱脉冲响应(CIR)法测定一系列小分子芳香化合物、香豆素类化合物、黄酮类化合物以及脂肪酸甲酯化合物在超临界溶剂及夹带不同改性剂的超临界流体中无限稀释扩散系数，首次将改进的CIR法应用于于极性和大分子量、高粘度液体及固体溶质的二元及三元体系的扩散系数测定；采用实验测定与量子化学相结合的研究手段从分子层面系统研究超临界流体的物化性质、不同类型溶质的构型和性质、改性剂的类型、以及体系中分子间作用力对溶质扩散系数的影响规律，从微观分子水平探究传递作用机制；并在此基础上，构建了关联溶质扩散系数和溶质分子结构特性的定量构效关系模型，首次提出关联溶质-溶剂相互作用能的修正流体力学和粗糙硬球模型，以及线性溶剂化能模型，这些模型对于超临界流体中溶质的二元体系及三元体系扩散系数均获得良好的预测效果；以上研究为超临界流体技术在相关工业领域中的应用奠定坚实的理论和实践基础。