Vapour adsorption on rutile pretreated with water, ethanol, hexan-1-ol and hexan-1 : 6-diol

Sorption data of nitrogen at 77 K, water and ethanol at 298 K and n-pentane at 273 K have been obtained for pure rutile outgassed at 673 K and modified by presorption of water, ethanol, hexan-1-ol and hexan-1 : 6-diol. All adsorbates interact strongly with the unmodified surface. With presorbed water and organics the extent and energy of nitrogen sorption is reduced. Organic-pretreated surfaces are largely hydrophobic, but also show reduced n-pentane adsorption. Hexan-1 : 6-diol is oriented parallel to the rutile surface by strong interactions through the hydrocarbon chain and both hydroxyl groups. Although not initially adsorbed in perpendicular orientation, hexanol has this configuration at high relative pressures of n-pentane which then penetrates the presorbed layer. Ethanol exchanges with both presorbed water and hexan-1-ol but not with hexan-1 : 6-diol.