Investigation of Aqueous Biphasic Polyethylene Glycol Systems for the Selective Liquid/Liquid Extraction of Dissolved Metal Ions

该建议涉及使用水性双相盐 由聚乙二醇（PEG）和无机盐组成， 分离溶解的金属离子。当将PEG和盐加入到 水，溶液分离成两个不同的层;一个 一相富含PEG，另一相富含盐。金属离子 溶解在该系统中的化合物优先溶解在PEG中 富相，因此离子分离可以通过简单地 将聚合物和盐溶解在含金属的水溶液中， 流，然后分离各相。的变量 影响金属分配的因素有pH值、盐的选择、PEG 浓度、温度和距离临界点的距离 点（即，两相 第一次出现）。 提出了几个关键的研究领域： (i)在以前的研究中，PI已经证明了一系列 在批量实验中，TcO 4-形式的锝可以 使用碳酸盐（K2 CO 3）将其萃取到富PEG相中 和硫酸盐（（NH 4）2SO 4，而不需要络合 剂PI打算进一步研究这一新结果， 在这个发现的基础上， 金属离子从富PEG相中分离并完成分离 过程将测试几种方法，包括离子 交换，和油-水间歇萃取与PEG作为 水相 (ii)优化特定的两相系统（SO 42-、CO 32-、PO 43-或 用于选择性去除Tc或Cr（在碱性介质中）， CrO41-）。 (iii)碱金属和碱土金属的碱侧提取 高碱度合成废液中的离子， 硝酸盐浓度高。 (iv)用于去除有毒金属阳离子的两相系统 使用无机阴离子形成可萃取的络合阴离子， 金属. (v)两相体系中的有机分离 (vi)使用水溶液和水溶液的组合的F-元素提取 两相和水溶性萃取剂。

This proposal is concerned with using aqueous biphasic salts composed of polyethylene glycol (PEG) and an inorganic salt to separate dissolved metal ions. When PEG and salt are added to water, the solution separates into two distinct layers; one phase is rich in PEG and the other in salt. Metal ions dissolved in this system preferentially dissolve in the PEG rich phase, and hence ion separation can be effected by simply dissolving polymer and salt in a metal-containing aqueous stream, and then separating the phases. The variables which affect the metal partitioning are the pH, salt selection, PEG concentration, temperature and distance from the critical point (i.e. the polymer/salt composition at which two phases first appear). Several critical areas are proposed for study: (i) In previous research, the PI has demonstrated in a series of batch experiments, that technetium in the form of TcO4- can be extracted into the PEG rich phase using carbonate (K2CO3) and sulphate ((NH4)2SO4 without the need of a complexing agent. The PI intends to study this novel result further, and to build on this discovery by finding a method to strip the metal ions from the PEG-rich phase and complete the separation process. Several methods will be tested including ion exchange, and oil-water batch extraction with the PEG as the aqueous phase. (ii) Optimize particular biphasic systems (SO42-,CO32-, PO43- or alkmaline media) for the selective removal of Tc or Cr (in the form of CrO41-). (iii) Base-Side extraction of alkali and alkaline earth metal ions from synthetic waste solutions of high alkalinity and high nitrate concentration. (iv) Biphasic systems for the removal of toxic metal cations using inorganic anions to form extractable complex anions of metals. (v) Organic separations in biphasic systems (vi) f-element extraction using a combination of aqueous biphase and water soluble extractant.