疏水性低共熔溶剂的设计、性质及其对环境污染物的萃取分离

Deep-eutectic solvents (DESs) are a new generation of green solvents, and they have the advantages of simple preparation, low toxicity and low cost as well as the excellent properties of ionic liquids. However, due to the hydrogen bonding with water, most deep eutectic solvents cannot be used in aqueous systems. In this project, we are going to design and synthesize a series of new hydrophobic DESs, which are applicable for aqueous systems, by selecting different frameworks of hydrogen bonding donors (HBD) and hydrogen bonding acceptors (HBA). The effects of water solubility, acid-base property, structural type, functional groups characteristics and hydrogen bonding ability of HBD and HBA on the physico-chemical properties of the synthesized DESs, such as melting point, thermal stability, hydrophobicity, and viscosity, will be investigated to understand the structure – property relationship of the hydrophobic DESs. Then, we will determine experimentally the distribution coefficients of some typical environmental pollutants between DES and water phases, percentage extraction, extraction equilibrium time and other extraction parameters, study temperature, ionic strength and solution pH effects, evaluate the extraction and separation performance of DESs for the environmental pollutants in water, and reveal the related mechanism by combination with spectroscopy measurements. On this basis, attempt will be made to use hydrophobic DESs for several sample micro-treatment technologies such as solid phase / liquid phase micro-extraction, which may then be combined with chromatography and molecular spectroscopy to establish new green separation and analysis methods for environmental pollutants in water. The results of this work would provide foundational and technical supports for the development of new, cheap, environmentally friendly solvents in the field of environmental interests.

低共熔溶剂是一类制备简单、低毒价廉、具有离子液体优良特性的新一代绿色溶剂。但是，由于与水的氢键作用，绝大多数低共熔溶剂不能用于含水体系。本项目拟选择具有不同骨架的氢键供/受体，设计合成一系列适用于含水体系的新型疏水性低共熔溶剂。考察氢键供/受体的水溶性、酸碱性、结构类型、官能团特性和形成氢键的能力对低共熔溶剂的熔点、热稳定性、疏水性、粘度等物理化学性质的影响，认识疏水性低共熔溶剂的结构-性质之间的内在联系。测定代表性环境污染物在低共熔溶剂-水两相中的分配系数、萃取率、萃取平衡时间，研究温度、离子强度、溶液pH值的影响，评价低共熔溶剂对水相环境污染物的萃取性能，并结合谱学研究, 阐明相关机制。在此基础上，将疏水性低共熔溶剂用于固相/液相微萃取等样品预处理，并与色谱、分子光谱技术联用，建立水相环境污染物的绿色分离分析新方法，为廉价、环境友好的新一代绿色溶剂在环境领域的应用提供理论和技术支持。

低共熔溶剂（DESs）是一类制备简单、低毒价廉、且具有离子液体优良特性的新一代绿色溶剂。但是，由于与水的氢键作用，绝大多数DESs不能用于含水体系的萃取/分离。本项目筛选出12个氢键受体和42个氢键供体，设计合成了60种适用于含水体系的新型疏水性DESs。测定了它们的熔点、密度、粘度和接触角等相关物理化学性质，考察了氢键供/受体的水溶性、酸碱性、分子结构、官能团的类型和形成氢键的能力对DESs性质的影响。研究了所制备的疏水DESs对环境内分泌干扰物、小分子挥发性有机物、食品添加剂、药物残留以及铬等34种有机污染物和重金属的萃取性能，考察了萃取平衡时间，萃取温度、溶液pH等因素的影响，确定了疏水DESs用于萃取的各项技术参数和使用条件，并结合谱学研究，提出了DESs对目标污染物的氢键作用、离子交换和静电作用的协同萃取机理。在此基础上，将疏水DESs用于环境水、室内空气、个人护理品、食品、生物制品、食品接触塑料、体液等多种实际样品的固相/液相微萃取处理，并与色谱、分子光谱技术联用，建立了20余种痕量水相污染物的快速绿色分离分析新方法以及不同浓度污染物的绿色样品前处理新技术。研究结果表明，与传统的挥发性有机萃取溶剂相比，制备的疏水性DESs的萃取性能表现出明显的优势，例如，较低的检出限，较高的富集因子，优异的选择性能，良好的抗干扰能力。即使在0.05 μg/L的超痕量浓度时，一些DESs对目标污染物的萃取率仍高达90％以上，富集因子最高达到700，萃取容量可达504 mg/g，在高含量盐（1.0 mol/L）存在时，不影响目标物的萃取。而且由于其独特的结构可设计性、氢键作用和低挥发性，可以针对目标物的结构性能灵活设计对应的DESs，也可以方便的回收、再生和循环利用。本研究为廉价、环境友好的新一代绿色溶剂在环境领域的应用提供了理论和技术支持。