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Development of high-performance separation methods of inorganic compounds based on aqueous biphasic extraction systems

基于水相双相萃取系统的无机化合物高性能分离方法的开发

基本信息

批准号：
14540563
负责人：
SHIBUKAWA Masami
金额：
$ 2.18万
依托单位：
Nihon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Aqueous biphasic systems(ABS) are formed by mixing water, certain inorganic salts and water-soluble polymers and can be efficient for the separation of inorganic compounds as well as of organic compounds. Polyethylene glycols(PEG) are nontoxic, nonflammable and nonvolatile so that the PEG-based ABS can be regarded as environmentally friendly, in contrast to conventional solvent extraction systems utilizing water immiscible organic solvents. A number of investigators have considered that water molecules in ABS should play an important role in separation processes and therefore an understanding of the states of water in the polymer systems is of great importance in the elucidation of the mechanism of separation in ABS. We have thus studied, at first, the states of water in PEG gel as well as poly(vinyl alcohol)(PVA) gels by means of liquid chromatography and differential scanning calorimetry. It was found that the estimated amount of the stationary phase water is in good agreement with the sum of the amount of non-freezing water and that of freezable bound water for most of the PVA gels, while it agrees with the amount of only non-freezing water for the PEG gel. This result can be attributed to the difference in the structure of the gels ; the PVA gels containing PVA at relatively high concentrations have a homogeneous gel phase, whereas the PEG gel have a heterogeneous gel phase consisting hydrated polymer domains and relatively hydrophobic domains.Separation of inorganic anions and metal ions was investigated using high-speed countercurrent chromatography with aqueous biphasic systems consisting of PEG and sodium sulfate. The PEG-rich upper phase was used as the stationary phase and the salt-rich lower phase was used as the mobile phase. Separation of some inorganic anions and that of chromium(III) ion and chromate(VI) ion were easily accomplished by HSCCC with PEG#1000-Na_2SO_4 ABS.

双水相体系(ABS)是由水、某些无机盐和水溶性聚合物混合而成的体系，可以有效地分离无机化合物和有机化合物。聚乙二醇组分具有无毒、不燃、不挥发等特点，与传统的不溶于水的有机溶剂萃取体系相比，聚乙二醇基ABS具有环保的特点。许多研究人员认为ABS中的水分子应该在分离过程中发挥重要作用，因此了解聚合物体系中水的状态对于阐明ABS中的分离机理具有重要意义。因此，我们首先用液相色谱和差示扫描量热法研究了水在聚乙二醇凝胶和聚乙烯醇(PVA)凝胶中的状态。结果表明，大多数PVA凝胶的固定相水量与非冻结水和可冻结结合水的量之和吻合较好，而聚乙二醇凝胶只有非冻结水的量符合得较好。这一结果可以归因于凝胶结构的不同：含有较高浓度PVA的PVA凝胶具有均匀的凝胶相，而聚乙二醇凝胶具有由水化的聚合物结构域和相对疏水的结构域组成的非均相凝胶相。以富聚乙二醇上相为固定相，富盐下相为流动相。在聚乙二醇1000-Na2SO4 ABS存在下，HSCCC很容易实现部分无机阴离子的分离和铬(III)、铬(VI)离子的分离。