Specific Extraction of Multivalent Inorganic Cations Using Supramolecular Systems

• Applicant: Dr. Oliver Zech
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: Funded in 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 190310880

In the following research proposal a separation strategy by means of ion specific flotation experiments will be developed and realized.In systems consisting of mixtures of fluorinated and hydrogenated surfactants two different coexisting types of micelles will be created. On the one hand, micelles that mainly consist of fluorinated surfactants, on the other hand, micelles that are preferentially formed by conventional surfactants. This can be achieved by a targeted choice of surfactant type, surfactant head group and surfactant chain length. Since a separation strategy for multivalent cations will be developed, for the mixed micellar systems anionic surfactants, with a carboxylate head group for the fluorinated surfactants and a sulphonate head group for the hydrogenated surfactants, are adapted.By the addition of water soluble salts of trivalent cations, these ions will be bound with different strength in the adsorption layer of the micelles due to the different size and polarizability. This ion affinity towards the surfactant head groups forms the basis of the separation strategy. Subsequent to the investigation of these mixed micellar systems in presence of the salts via small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS) and NMR methods an ion separation by means of flotation experiments will be performed.In the foam phase the surfactants should have different affinity towards the air-water interface due to the significant differing properties of fluorinated and hydrogenated surfactants with respect to polarity and solubility. An enrichment of one surfactant type will afford a separation of metal cations, since they are associated with different strength to the surfactant head groups. This enrichment of one surfactant type in the foam phase can be verified by NMR-methods, the concentration of the cations can be determined via inductively coupled optical emission spectrometry (ICP-OES).

• DFG Programme: Research Fellowships
• International Connection: France
• Host: Professor Dr. Thomas Zemb