Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 19: POSTER: Micro and Nano Fluidics
CPP 19.5: Poster
Mittwoch, 28. März 2007, 16:00–18:30, Poster B
A Study on the Permeability of Nanoporous Vycor — •Simon Grüner1, Stefanie Greulich1, Dirk Wallacher2, and Patrick Huber1 — 1Saarland University, Saarbrücken, Germany — 2Hahn-Meitner Institute, Berlin, Germany
We have designed and built a membrane flow apparatus (MFA) to measure the liquid permeability K of porous monoliths such as nanoporous Vycor as a function of applied pressure difference Δ P (0 < Δ P < 70bar), temperature T and pore wall chemistry (silanization). The pore structure of the matrix (mean pore diameter d≈ 8nm, porosity φ≈ 30%) is characterized by nitrogen sorption isotherms at T = 77K.
First measurements of the volume flow rate V of n-hexane through Vycor at T=18∘C nicely confirm Darcy’s law, that is V ∝ Δ P. Nonetheless the derived permeability K is somewhat smaller than expected from calculations assuming the above mentioned values for φ and d. We rather obtain a best agreement between experiment and theory with a pore radius 0.4nm smaller than that derived from the sorption isotherm. This reduction corresponds to about one immobile monolayer (boundary layer) of lying hexane molecules at the wall.
This work has been supported by the DFG within the priority program 1164 (HU850/2-1).