Simultaneous adsorption of toluene and water vapor on a high surface area carbon

Small angle neutron scattering is used to study the simultaneous adsorption of toluene and water vapor by a commercial high surface area carbon, oxidized to enhance its affinity for polar molecules. Owing to the smaller size of the molecule, water on its own penetrates the smallest defects in the carbon matrix more efficiently than does toluene, as revealed by the density of the carbon determined by contrast variation. Pore filling by water, however, is less complete. When water and toluene vapor are simultaneously present, they coexist in the pores, toluene being the dominant component and water accounting for about 12% of the total adsorbate. Phase separation is not observed. The carbon acts as a compatibilizer for the two different molecules.