Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Poster: Interfaces and Thin Films
CPP 13.22: Poster
Dienstag, 27. März 2012, 18:15–20:45, Poster A
Adsorption of supercritical fluids on solids — Sebastian Holz, •Julia Nase, Michael Paulus, Christian Sternemann, Thorsten Brenner, and Metin Tolan — Fakultät Physik/DELTA, TU Dortmund, 44221 Dortmund
Adsorption at interfaces is critical for many processes in nature, as formation of gas hydrates, catalysis, or industrial applications like water purification. The formation of an adsorption layer enhances the gas offer significantly and is thus of importance for transport and exchange processes at membranes and interfaces in nature. More than 100 models have been established to describe the various types of adsorption isotherms. Supercritical adsorption, however, is far less understood, though this phenomenon has been known for some time now. It has tremendous importance in industrial applications like high pressure gas storage systems, Supercritical Fluid Chromatography (SFC), and polymer processing. So far, supercritical adsorption was investigated indirectly by volumetric and gravimetric methods in highly porous systems. However, the solid-gas interface with a possible restructuration of the molecules has never been directly measured. The exact density profile along the surface normal can be determined by x-ray reflectometry, a reliable and well adapted technique to determine interfacial structures. We report on results concerning the adsorption of supercritical carbon dioxide on a silicium wafer. Adsorption isotherms below the critical point are compared to the near critical (T<TC+10K) and the over critical regime (T>TC+10K ).