Simple Devices for the Measurements of Absorption Spectra at Liquid-Liquid Interfaces
Simple Devices for the Measurements of Absorption Spectra at Liquid-Liquid Interfaces
复制标题
用于测量液-液界面吸收光谱的简单装置
DOI：
10.2116/analsci.10.105
复制
发表时间：
1994
影响因子：
1.6
通讯作者：
Yoshito Chida
中科院分区：
文献类型：
--
作者：
H. Watarai;Yoshito Chida
液-液界面化学反应是分析科学中的一个重要研究课题，特别是在溶剂萃取、液膜分离、逆流色谱和离子选择性液膜电极等方面。界面在溶剂萃取金属离子中的作用在我们最近的工作中得到了证实，我们采用了高速搅拌方法，以获得搅拌体系，高比界面面积和促进传质的优点。当比界面面积大时，溶质的界面吸附可导致有机相浓度的显著降低。这种浓度的降低可以通过使用聚四氟乙烯相分离器连续相分离后的荧光光度法测量。2这种方法适用于测量提取率以及各种提取系统中的界面吸附。然而，这是一种间接方法，用于检测界面吸附。因此，需要一种直接的光谱方法来识别界面吸附的物种。在用于测量液-液界面吸收光谱的方法中，全内反射法被认为是最有用的方法，除非有机相含有强吸光物质。3不幸的是，溶剂萃取中遇到的有机相通常含有有色物质，因此该方法的应用受到限制。本文提出了两种测量界面吸收光谱的方法，即光搅拌池法和聚四氟乙烯毛细管板法。这两种装置都是基于与高速搅拌方法相同的原理发明的;比界面面积的增加扩大了界面浓度的比例。这些方法成功地应用于四苯基卟啉（TPP）在甲苯/硫酸体系中的界面光谱的测量。
Chemical reactions at liquid-liquid interfaces are an attractive subject in analytical sciences, especially in studies of solvent extraction, liquid membrane separation, counter current chromatography and ionselective liquid membrane electrodes. The role of an interface in the solvent extraction of metal ions was demonstrated in our recent work where we employed a high-speed stirring method to gain advantages of an agitated system, a high specific interfacial area and promotion of mass transfer.l The principle of this method is as follows; when the specific interfacial area is large, interfacial adsorption of a solute can result in a significant decrease of the orgaic phase concentration. This concentration decrease can be measured spectrophotometrically after continuous phase separation by use of a Teflon phase separator.2 This method was applied to measurements of extraction rates as well as to interfacial adsorption in various extraction systems. This is, however, an indirect method with respect to detection of interfacial adsorption. Consequently, a direct spectroscopic approach is desired to identify interfacially adsorbed species. Among the methods proposed for measurements of absorption spectra at liquid-liquid interfaces, the total internal reflection method is thought most informative unless the organic phase contains strongly lightabsorbing species.3 Unfortunately, an organic phase encountered in solvent extraction usually contains colored species, and hence the application of this method is limited. Two methods, an optical stir cell method and a Teflon capillary plate method, are proposed in this work for measurements of interfacial absorption spectra. Both devices were invented based on the same principle as the high-speed stirring method's; an increase in the specific interfacial area enlarges the proportion of the interfacial concentration. These methods were successfully applied to measurements of interfacial spectra of tetraphenylporphyrin (TPP) in a toluene/sulfuric acid system.