Dilute aqueous systems, kinetic studies

The radiation chemistry of aqueous solutions may be considered from two points of view. The first, called the Target Theory, considers the direct effect of ionizing radiations on the solute molecules. The second approach regards transformations in the solute molecules to be attributed to interactions with the reactive intermediates formed by the radiolysis of water. Because most aqueous systems are relatively dilute, the latter approach seems statistically more reasonable. Kinetic studies of dilute aqueous systems have indeed borne out this supposition. The radiation chemistry of aqueous solutions then becomes the free radical and redox chemistry of H-, OH-, and e q. 

In order to develop the liquid membrane techniques, i.e., emulsion Hquid membrane (ELM), supported liquid membrane (SLM), non-dispersive extraction in hollow fiber membrane (HFM), etc., for practical processes, it is necessary to generate data on equilibrium and kinetics of reactive extraction. Furthermore, a prior demonstration of the phenomena of facilitated transport in a simple liquid membrane system, the so-called bulk liquid membrane (BLM), is thought to be effective. Since discovery by Li [28], the liquid membrane technique has been extensively studied for the separation of metal ion, amino acid, and carboxyHc acid, etc., from dilute aqueous solutions [29]. 

In this article we shall focus on recent work involving dilute aqueous surfactant solutions. As a background the thermodynamics and statistics of these solutions will be discussed first (Section II). The distribution of substrate molecules in microheterogeneous solution is considered in Section m. It is decisive for the kinetics of elementary photochemical reactions (Section IV), which depend on the peculiar colloidal solution structure. Effects of the microscopic environments on photochemical reactions are treated in Section V. Finally, the use of known photochemical systems as probes for studying details of the structure of surfactant solutions will be considered in Section VI. 

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