Heterogeneity of the glass fiber surface from inverse gas chromatography

The chromatographic peak profiles of hexane and butanol on a column packed with E-glass fibers show that the surface of the fiber is homogeneous for hexane and heterogeneous for butanol. The distributions of adsorption sites in energy and entropy are obtained separately by a new method. This method is a generalization to heterogeneous surfaces of the widely used method of determination of the entropy and the energy of adsorption from the temperature dependence of the Henry constant. It is shown that the assumption that the entropy of adsorption can be taken as constant for all the adsorption sites (such an assumption is usually made in the literature) is not true for butanol. Another new result is the plot of entropy vs energy for different sites. This plot allows one to exclude the unreliable portion of the energy distribution.