Comparative adsorption study of dodecanol and cholesterol from ethylene glycol on the mercury electrode and air/solution interface

Abstract

The results of an adsorption study of dodecanol and cholesterol at the Hg/ethylene glycol solution interface and at the free surface of ethylene glycol are presented. The significant differences in the adsorption behaviour of these two compounds are discussed comparing the values of the adsorption parameters (standard Gibbs energy, interaction parameter and maximum surface concentration) obtained by fitting the experimental points to the Frumkin isotherm. In the case of cholesterol the standard Gibbs energy, ΔG°, is markedly greater for adsorption on the mercury than at the free surface. In the case of dodecanol, the difference in ΔG° values at both interfaces is insignificant. The plausible surface orientations of these two substances at both interfaces are discussed.