Adsorption of hydrocarbons on silica-supported water surfaces

Adsorption of a Diverse Set of Organic Vapors on the Bulk Water Surface

“…[10] Figure 5 shows adsorption constants for seven surfaces calculated with Eq. [10] plotted against experimental values (31,(51)(52)(53)(54)(55)(56). Apparently, Eq.…”

“…The good agreement of the BET measurements of the Chromosorb P surface area with its calculated surface area at low loading is encouraging because, until now, the assumptions in Refs. (1,(6)(7)(8)(9)(10) for the surface area of the water were uncertain. The surface area of the water film cannot be measured itself.…”

“…Hoff et al (1) then based their calculations of the water surface area on the adsorption coefficient for heptane from Karger and co-workers (6-9), identically as in our procedure. Dorris and Gray assumed that K i surf/air for alkanes is the same for a support equilibrated at 88% relative humidity and covered with 20% (w/w) water (10), which also is a questionable assumption (15). Therefore, the data available in the literature until now were all dependent on the correctness of Karger's or of Dorris and Gray's assumption regarding the specific water surface area.…”

“…Apparently, Eq. [10] describes the van der Waals interactions of various surfaces well over a very wide range.…”

“…To date, air-water surface adsorption coefficients, K i watersurf/air , have been measured only for a very restricted set of primarily nonpolar or weakly polar organic compounds (1,(6)(7)(8)(9)(10). These data do not allow a thorough quantification of the electron-donor and -acceptor properties of the bulk water surface.…”