Physical model for gas-solid chromatography with volatile and nonvolatile modifiers

Abstract

The two-dimensional (adsorption) version of the scaled particle solution theory has been used to interpret the single-component isotherms of propane, butane, and acetone on a graphitized carbon black adsorbent over a range of temperatures. In addition, the multicomponent adsorption model has been used to develop an equation to describe the retention volume of an infinite dilution solute as a function of surface coverage by a volatile modifier as well as to interpret the experimental results from previous investigations of such quasi-binary chromatographic systems. Several sets of binary chromatographic data in the form of the retention volume of one solute as a function of the surface coverage by a different solute were regressed to the proposed retention volume equation. The adsorption coefficients of each solute obtained from the binary isotherm data (propane + butane and acetone + butane) agreed with those determined from the single-component isotherms as well as those calculated from specific retention volumes of the infinite dilution solutes with no modifier present. The retention volume equation provides the first quantitative description for the retention of one solute as a function of the surface coverage by a second component.