镍电解液深度除铜用高选择性新型硅胶负载螯合树脂的设计、制备及螯合机制研究

The elements of copper and nickel have similar atomic radii and similar chemical properties, which makes the deep removal of copper from nickel electrolyte anode solutions becoming the hard problem that has troubled metallurgical industries at home and abroad over a long period of time. Compared with other current methods of copper removal from nickel electrolytes, the method of copper removal using the existed aminomethyl pyridine silica-supported chelating resin has following advantages, such as no slag production, no electrolyte pollution, high absorption rate, resin recycling, and so on. However, the selectivity of copper over nickel using this silica-supported chelating resin is not high. An extractant called 2-aminomethyl pyridine containing tertiary amine group was invented by our research group in our primary study, the maximum selectivity coefficient of copper over nickel for this extractant is 2027 with excellent properties of copper removal from nickel electrolytes. On the basis of the feature structure of this invented extractant, a series of novel silica-supported 2-aminomethyl pyridine resins containing tertiary amine groups will be designed and synthesized. The chelating mechanism between the synthesized resins and the copper/nickel species of nickel electrolytes will be investigated at atom or molecule level by the combination of traditional methods of typical thermodynamics and kinetics, modern characterizations and quantum chemical calculation, and then the relationship among the structure of the synthesized chelating resins, the properties of nickel electrolytes and the separation selectivity of copper over nickel will be illuminated by the combination of the above-obtained chelating mechanism and the absorption properties of the synthesized chelating resins. And then the principle and the method of regulation and control of the structures of the resins, which can be potentially used as adsorbents for highly selective separation of copper over nickel, will be formed. By corrective feedback operations, novel silica-supported 2-aminomethyl pyridine resins containing tertiary amine groups will be ultimately obtained and these resins will have highly selective removal of copper from nickel electrolytes. The research results from this project can be provided as a theoretical support for the formation of new methods and technologies of deep removal of copper from nickel electrolytes.

铜镍原子半径相近，化学性质相似，导致镍电解阳极液深度除铜成为长期困扰国内外冶金界的难题。与其他方法相比，现有氨甲基吡啶硅胶负载螯合树脂除铜法具有不产生除铜渣、不污染电解液、吸附速率快、树脂可循环利用等优点，但铜镍分离选择性不高；前期研究发明含叔胺基团的2-氨甲基吡啶萃取剂，铜镍分离系数最高达2027，深度除铜效果优良。本项目拟以此萃取剂结构为基础，设计并制备一系列含叔胺基团的2-氨甲基吡啶新型硅胶负载螯合树脂，借助经典热力学与动力学、现代表征技术与量子化学理论计算相结合方法，从原子分子水平研究树脂与镍电解液中铜镍物种的螯合机制，结合树脂的吸附性能研究结果，阐明螯合树脂结构-镍电解液性质-铜镍分离选择性间对应关系，形成铜镍高选择性分离用螯合树脂结构调控原理与调控方法，经反馈修正，最终获得深度除铜用高选择性新型硅胶负载螯合树脂。该研究成果将为镍电解液深度除铜新方法与新技术的形成提供理论支撑。

铜镍原子半径相近，化学性质相似，导致镍电解阳极液深度除铜成为长期困扰国内外冶金界的难题。本项目针对现有氨甲基吡啶硅胶负载螯合树脂除铜法的铜镍分离选择性不高的主要问题，合成了二齿配体、三齿配体和四齿配体的三种2-氨甲基吡啶类衍生物萃取剂（简记为AMPO、AMPY和AMPA），分别研究了其对铜镍和铜钴的分离选择性，采用等摩尔比法、单晶培养和单晶衍射法、X-射线光电子能谱(XPS)、电喷雾质谱（ESI-MS）和量子化学理论计算等方法，研究了铜镍钴离子与2-氨甲基吡啶类衍生物的相互作用机制，我们发现，既含酯基又含叔胺基团的2-氨甲基吡啶为铜镍和铜钴分离选择性最好的配体。在此基础上，制备了既含酯基又含叔胺基团的2-氨甲基吡啶硅胶负载螯合树脂并对其吸附性能进行了表征，结果表明，该硅胶负载螯合树脂的吸附容量不高，对铜离子的最大饱和吸附容量仅为0.67mmol/g干树脂，存在吸附容量过低的问题。为此，我们合成了三种聚苯乙烯基2-氨甲基吡啶类螯合树脂（简记为PS-AMP、PS-AMPO和PS-AMPA），采用XPS表征技术和基于DFT的量子化学理论计算方法相结合，从原子分子层次进一步揭示了三种树脂与铜镍的相互作用机制，并对其吸附性能进行了表征。结果表明，三种聚苯乙烯基2-氨甲基吡啶类螯合树脂, PS-AMP, PS-AMPO和PS-AMPA，对铜离子的最大饱和吸附容量分别为1.33mmol/g干树脂、0.88mmol/g干树脂和1.23 mmol/g干树脂，三种树脂的铜镍和铜钴选择性由大到小顺序为PS-AMPAPS-AMPOPS-AMP。在所研究的双金属溶液浓度范围内，PS-AMP、PS-AMPO和PS-AMPA的铜镍分离选择性系数分别最高达643、1979和2241，而铜钴分离系数分别最高达1104、2342和2414；对模拟镍电解液进行动态吸附实验中，前20BV、8BV和18BV净化流出液中铜含量低于3 mg/L，PS-AMP、PS-AMPO和PS-AMPA铜负载树脂的解吸液中铜镍质量比分别为5:1、15:1和15:1；在模拟钴电解液中，前22BV、10BV、20BV时净化流出液中铜含量低于3 mg/L, 铜负载树脂的解吸液中铜钴质量比分别为7:1、20:1和20:1。因此，PS-AMPA螯合树脂有望用于镍或钴电解液的深度净化除铜。