Kinetic processes of adsorption of 1-octyn-3-ol on iron in HCl solutions

Abstract

The interfacial kinetic processes of adsorption of 1-octyn-3-ol on Fe in HCl solutions were studied as a function of concentration, potential and temperature by in situ time-resolved automatic ellipsometry. Effects of chloride on the adsorption process were further examined by XPS and 36Cl-radiotracer measurements. It was shown that as the octynol concentration in solution increases or the adsorption time increases, the orientation of the adsorbed octynol on the electrode surface changes from flat orientation, to partly-upright, and to the upright orientation, followed by continuous growth of a multilayer polymer film. These processes proceed faster with increasing temperature. The growth of the polymer film proceeds through a distinct “layer by layer” fashion, with the molecule assuming the upright position inside the film. The presence of Cl − reduces octynol adsorption substantially due to competitive adsorption, but it speeds up the reorientation process.