Study of the Interfacial Properties of Water by Gas Chromatography

A review of our work on the study of the interfacial properties of water by gas chromatography is presented. The theory and practice of this method is outlined, along with a critical analysis of sources of error. In this method, the retention of nonelectrolytes is measured as a function of temperature and sample size. For some solutes, adsorption at the gas-liquid interface is the only mechanism of retention, and thus one can determine thermodynamic quantities of adsorption and equations of state directly. For other solutes (e.g. aromatics) both partition and adsorption simultaneously occur, resulting in a slightly more sophisticated analysis to extract both solution and adsorption phenomena. The results indicate that water is a low energy surface to hydrocarbons. Anti-Langmuir adsorption isotherms reveal that the hydrocarbon is more attracted to itself in the liquid surface than to the water molecules. Also shown for the first time is the formation of hydrogen bond interactions between water surface molecules and Bronsted bases. (Author Modified Abstract) Prepared in cooperation with Wayne State Univ., Detroit, Mich. Dept. of Chemistry.