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

用于选择性液/液萃取溶解金属离子的水性双相聚乙二醇体系的研究

• 批准号: 9207264
• 负责人: Robin Rogers
• 金额: $ 24.11万
• 依托单位: Northern Illinois University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-15 至 1996-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9207264&HistoricalAwards=false
• 关键词: Investigation; Aqueous; Biphasic; Polyethylene; Glycol

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.

这一建议涉及使用由聚乙二醇（PEG）和无机盐组成的水相盐来分离溶解的金属离子。当PEG和盐加入水中时，溶液分成两层；一相富含聚乙二醇，另一相富含盐。溶解在该体系中的金属离子优先溶解在富含PEG的相中，因此只需将聚合物和盐溶解在含金属的水流中，然后分离相即可实现离子分离。影响金属分配的变量包括pH值、盐的选择、PEG浓度、温度和与临界点的距离（即两相首次出现时的聚合物/盐组成）。提出了几个关键的研究领域：(i)在之前的研究中，PI已经在一系列的批量实验中证明，可以使用碳酸盐（K2CO3）和硫酸盐((NH4)2SO4将TcO4-形式的锝萃取到富含PEG的相中，而不需要络合剂。PI打算进一步研究这一新结果，并在此基础上找到一种方法，从富含peg的相中剥离金属离子并完成分离过程。将测试几种方法，包括离子交换和油水间歇萃取，以聚乙二醇为水相。（ii）优化特定的双相体系（SO42-、CO32-、PO43-或碱性介质），以选择性去除Tc或Cr（以CrO41-的形式）。（三）从高碱度、高硝酸盐浓度的合成废液中碱和碱土金属离子的碱侧萃取。（四）用无机阴离子形成可萃取的金属复合阴离子去除有毒金属阳离子的双相系统。(v)双相系统中的有机分离（vi）使用双水相萃取剂和水溶性萃取剂的组合萃取f元素。