超临界二氧化碳络合萃取技术在医药食品、材料科学、原子能工业、湿法冶金等领域有广泛的应用前景。实现该技术的必要条件是金属螯合物在超临界二氧化碳中有足够高的溶解度，但现有的萃取剂与金属离子配合形成的螯合物要么在超临界二氧化碳中溶解度太低，要么含氟价格昂贵，限制了该技术的应用范围。为了解决这一难题，本申请提出以金属螯合物在超临界二氧化碳中的溶解度作为选择萃取体系的重要指标之一，通过测定具有不同结构的金属螯合物在超临界二氧化碳中的溶解特性，探索金属螯合物的结构与溶解度之间的定量结构－性质关系，筛选出适合于超临界二氧化碳络合萃取的无氟萃取剂及与之匹配的金属离子，并为有效的选取萃取体系，进而合理设计和开发新型萃取剂提供必要的依据。本申请的研究成果不仅能推动超临界二氧化碳络合萃取技术的进一步发展和大规模应用，而且对我国的国防工业、冶金工业和化学工业的发展都有很好的促进作用。

Supercritical CO2 technology is environment-friendly chemical technology. Extraction of metal ions by supercritical CO2 has been a hot research topic, but the traditional chelating agents are not favourable because of the limited solubility along with low selectivity. An unique type of neutral organic phosphate chelating agents, (CH2CH2O)mCH2CH2[OP(O)(OR1)(OR2)]2, with the structure of open-chain crown ethers have benn designed and prepared in this project. Solubilities of a series of new chelating agents in supercritical CO2 have been determined using static method. It was indicated that new chelating agents had a strong affinity to CO2, short linkages and branching-lateral chains without oxygen incorporated in provided high solubility. The solubility in supercritical CO2 is as high as 10-2 mole fraction under experimental conditions. Supercritical CO2 extraction of metal ions from the solid matrix has been studied using thes chelating agents. They showed sufficiently stronger affinity to the trivalent lanthanides ions than the other divalent metal ions. It was significantly intriguing that the chelating agents with the bridge linkage of (CH2CH2O)4CH2CH2 exhibited favorable selectivity to the middle lighter lanthanide metal ions. In addition, the mass transfer and adsorption equilibrium which are important to supercritical CO2 extraction have been studied. The different between chelating extraction and microemulsion extraction of metal ions in supercritical CO2 were also investigated. These results are very valuable to select and design new chelating agents.

超临界CO2技术是环境友好的化工技术。超临界CO2螯合萃取金属离子一直是研究的热点，但传统螯合剂在超临界CO2中溶解度有限，萃取效率低且选择性差。本课题设计并制备了新型的具有开链冠醚结构的中性有机磷酸酯类螯合剂 (CH2CH2O)mCH2CH2 [OP(O)(OR1)(OR2)]2。测定了系列结构螯合剂在超临界CO2中的相行为和溶解度。新型螯合剂对CO2具有很强的亲和性，在研究范围内其在超临界CO2中的溶解度高达10-2 mol/mol。短桥链的螯合剂比长桥链的螯合剂溶解性好，在中间桥链相同的情况下，侧链含有分支拓扑结构且不含氧原子时，溶解性最好。应用新型螯合剂进行了超临界CO2从固体基质上萃取金属离子的研究，发现新型螯合剂对镧系金属离子可以实现高效萃取，并且在镧系范围内，萃取率随着离子半径的减小呈现“具有最高点的上凸曲线”趋势，即对镧系中部轻离子的具有良好的选择性。此外，本课题还对影响超临界CO2螯合萃取的传质和吸附平衡规律进行了系统研究，并将超临界CO2螯合萃取与微乳液萃取金属离子的效果进行了比较。研究成果对超临界CO2中螯合萃取体系的选择及新型螯合剂的合理设计具有重要的指导作用。