Incompatible Liquids in Confined Conditions

Liquides incompatibles en milieux confinés

Krisztina László (1) , Bruno Demé (2) , Orsolya Czakkel (2) , Erik Geissler (3)

1 Department of Physical Chemistry and Materials Science
2 ILL - Institut Laue-Langevin
3 BIOP-LIPhy - BIOP - Fluctuations, Régulation et Evolution des Systèmes Vivants

In applications involving organic vapour, the performance of high surface area carbons is often challenged by water vapour in the atmosphere. Small angle neutron scattering (SANS), through its ability to distinguish between different components by means of contrast variation, is ideally suited to investigating the behaviour of adsorbed layers in simultaneous contact with a mixed vapour phase. Even at high relative humidity (RH), water alone forms a discontinuous film composed of clusters on the surface of the oxidized microporous carbon used for these studies. When toluene is also present, all the available carbon surface is wetted. Toluene and water adsorb as a single phase already at RH 11.5%, and the concentration of water present in the adsorbed phase is as high as 2.9 wt.%, far above its solubility in bulk toluene (0.033 wt.% at 25 ºC). At RH 87% the concentration of water in the adsorbed phase is four times higher, approximately 12 wt.%. The recently proposed mechanism of anchoring of the water by the aromatic molecules may provide an explanation for this phenomenon.

Mots clés: high surface area carbon; water vapour; toluene; small angle neutron scattering; hydrophobicity; contrast variation

Domaines: Chimie-Physique [physics.chem-ph]

Krisztina László, Bruno Demé, Orsolya Czakkel, Erik Geissler. Incompatible Liquids in Confined Conditions. Journal of Physical Chemistry C, 2014, Journal of Physical Chemistry C, 118 (41), pp.5. ⟨10.1021/jp506100e⟩. ⟨hal-01132473⟩