Characterization of tetraaza-AC8, a surfactant with cation complexing potential

Being a surfactant with cation complexing potential, the Tetraaza-AC8 can, in the long term, possibly be applied for the selection and extraction of specific cations. This can be of interest for the handling of radioactive waste or in the chemical industries for extraction of rare earth molecules as for example Rhodium. A thorough characterization of the behavior and abilities of Tetraaza-AC8 is necessary before one can even think of taking it into a larger production with sight of a specific application. This project deals with the characterization of the behavior and abilities of Tetraaza- AC8. In order to make use of the surface active properties of Tetraaza-AC8 it is necessary to dissolve it in some kind of solvent. As water is an important solvent which is, in addition, both inexpensive and non-polluting it is the natural choice. The aim of the project can then precised as follows: To study the micelle formation of dilute aqueous solutions of Tetraaza- AC8 and to determine how the micelle formation is influenced by the addition of respectively CsF, CuF₂ and RhCl₃ to the solutions The primary method of analysis is small-angle scattering. As small-angle x-ray scattering (SAXS) and small-angle neutron scattering (SANS) emphasizes different parts of the micellar structure, the combination of the methods allows a good determination of the micellar shape. In order to support the interpretation of scattering data, density measurements, surface tension measurements and UV/visible light spectroscopy are also performed. The scattering data have been analyzed according to two fundamentally different methods of analysis namely the method of indirect Fourier transform and the method of fitting molecular based models of the micelles to the scattering spectra. The first chapter contains a short introduction to the field of surfactants and complexing macrocycles. The chemical structure of Tetraaza-AC8 will be explained and motivated. A short description of the synthesis will thereby be given. The second chapter contains descriptions of the fundamental physical chemical measurements made in order to characterize the molecule in aqueous solutions. In order to decide whether respectively CsF, CuF₂ and RhCl₃ is complexed by the Tetraaza-AC8 molecule, pH and UV/visible light spectroscopy measurements are performed. Density measurements of the molecule are made and will show to be applicable later, for the interpretation of the small-angle scattering spectra. Finally surface tension measurements are performed in order to prove that a micellization takes place and to determine the areas per head-group of the micelles, which will also show to be applicable later, for the interpretation of the small-angle scattering data. The third and fourth chapter deal with what we regard as the core of the project, namely the small-angle scattering analysis of dilute solutions of Tetraaza-AC8 with respectively CsF, CuF₂ and RhCI₃. Chapter 3 gives a short survey of the fundamental theory of small-angle scattering, thereby descriptions of the applied SAXS and SANS facilities are given. At the end of the chapter the raw-data obtained are presented and discussed. Chapter 4 deals with the analysis of the obtained scattering data. The principles of the two applied methods of analysis are explained. At the end of the chapter the obtained results are presented and discussed. During the project several different experimental methods and techniques have been applied. It should, however, be emphasized that since the project is of experimental nature, only brief surveys of the theory, methods and models applied will be given. More detailed descriptions can in most cases be found in the fundamental literature