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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 7: Interfaces and Thin Films II

CPP 7.6: Vortrag

Montag, 14. März 2011, 15:15–15:30, ZEU 114

The structure of the liquid-liquid water-CO₂ interface during hydrate formation — •Julia Nase¹, Felix Lehmkühler², Michael Paulus¹, Lars Böwer¹, Sebastian Tiemeyer¹, Sebastian Holz¹, and Metin Tolan¹ — ¹Fakultät Physik/DELTA, TU Dortmund, 44221 Dortmund — ²DESY, Hasylab, 22607 Hamburg

Hydrates are ice-like inclusion compounds with gaseous guest molecules in water cages. In recent years, they have incited the interest of researchers due to both their importance in oil industry (pipeline blockage) and as a promising possibility for CO₂ sequestration. Despite the increased interest, the formation process on a molecular level is still poorly understood. MD simulations predict the existence of different pre-structures, but an experimental proof is still pendant. Hydrate formation is generally thought to be initiated at interfaces. We report on a x-ray reflectivity study of the liquid-liquid water-CO₂ interface. This technique was shown to be a reliable tool to determine the thickness and roughness of interfaces and thin layers.

Previous studies on the liquid-gas interface in the theoretical hydrate stability region could not confirm the existence of precursor structures, however, a macroscopic hydrate phase did not occur. In our present study, the high offer in CO₂ molecules at the liquid-liquid interface resulted in a macroscopic hydrate formation. Results on the roughness of this interface beyond the stability region, an information that has been lacking so far, and on structural changes just before the appearance of a macroscopic hydrate phase are presented in this talk.