温控型功能化离子液体协同聚合膜选择性分离稀土金属的机理研究

It is quite difficult to separate the mixing rare earths elements from each other in the leaching solution of Ion-adsorption type rare earth mineral in southern China and mixing-rare earth mineral in Baotou, because there are many kinds of rare earths and other metal ions. In addition, there are also many mixing rare earths with low concentration in waste water for mining rare earth minerals. The direct discharge of mining waste water will lead to serious environmental issues, and cause the resource loss. Therefore, some methods will be mentioned to solve such problems in this proposal. In order to elevate the selective reorganization of specified rare earth, the polymer inclusion membranes associated with ionic liquids will be prepared and used in rare earth separation research; the novel synergetic separation system will be established through combining with membrane adsorption method and ionic liquid extraction method. The competition coordination between membrane adsorption, ionic liquid extraction and rare earth will be importantly discussed and solved. The separation mechanism and the ion mass transfer behaviors will also be revealed. More importantly, through tuning the parameters, including pore structure and surface modification of membrane materials, the number and type of functionalized groups, the volume of ionic liquids, to optimize the surface morphology of caves, asymmetrical structures of materials and other physicochemical properties. Hence, the selectively adsorption and the stability of the membrane materials will be highly enhanced, and then their separation ability will be obviously strengthened. The relationship between the microstructures of membrane and adsorption will be established, and the coordination mechanism between the rare earths and each kind of binding sites will also be investigated. Through synthesizing the temperature-dominated functionalized ionic liquids, the relationship between structural features and homogeneous liquid-liquid extraction will be optimized.

离子吸附型稀土矿和白云鄂博共伴生稀土矿浸出液中均含有多种稀土金属，难以分离。稀土矿采选废水中也含有大量低浓度、难分离的复杂混合稀土金属，直接排放不仅污染环境，而且造成资源的严重浪费。本项目将利用离子印迹表面修饰技术制备离子液体包埋型聚合膜材料，提高对稀土金属离子的专一性识别能力；通过将膜分离技术与离子液体萃取相结合，建立“膜吸附-萃取”新协同体系，揭示“膜-稀土离子-离子液体”之间的竞争作用、分离机理，阐明并强化协同体系的“吸附-扩散”传质行为。通过调控膜材料孔道结构、表面修饰、官能团种类和数量、离子液体载量等参数，优化膜材料的表面空穴形貌、结构的非对称性及理化性质，增强吸附的选择性和材料稳定性，提升对稀土金属的分离性能。建立微观结构与膜吸附之间的关系，探究膜材料各活性位点的络合机理。通过制备温控型功能化离子液体，优化结构特性与均相液-液萃取之间的关系。

本项目聚焦了我国重要战略资源稀土金属的分离研究，针对传统有机溶剂萃取中效率较低和环境污染等问题，提出了利用功能化离子液体在均相中实现对稀土金属的液液萃取，并采用离子印迹技术制备吸附材料及膜材料从而提高对某种稀土金属的去除选择性。按照项目计划书，首先开发了温控型羧酸功能化离子液体、季膦型羧酸功能化离子液体、季铵型羧基功能化双齿离子液体，分别研究了酸度、浓度、时间、温度等条件对萃取结果影响，重点研究了对稀土金属萃取机理、反萃取性能、对混合金属的分离能力。其次，开发了离子印迹聚合材料、PBA氧化衍生物、富N型COFs、氨基功能化UiO-66及其对应的4种膜材料，分别研究了粉体和膜材料对稀土金属的分离性能，重点讨论了酸度、时间、温度等条件对吸附结果影响。最后，利用离子液体与膜分离材料共同分离稀土金属溶液，构筑并优化了“吸附-萃取”协同体系。