Equilibrium and kinetic properties of cetyl-dimethyl-benzyl-ammonium chloride at the mercury/electrolytic solution interface by means of phase sensitive three-dimensional AC voltammetry

Abstract

The adsorption of cetyl-dimethyl-benzyl ammonium chloride (CDBACI) from aqueous electrolytic solutions on the polarized mercury electrode is studied by means of a recently developed methodology which allows the reconstruction of differential capacitance ( C) vs electrode potential ( E) curves at various time periods ( t). This methodology, which results in C-E-t surfaces and is therefore named Three-Dimensional AC Voltammetry, allows the simultaneous inspection of the time and potential dependence of adsorption processes on mercury. The micelle-forming character of CDBACl in bulk solutions is coupled with the interesting behavior of tetraalkylammonium cations on mercury, leading to extremely rich adsorption behavior with both potential and time variation. This behavior involves compact-layer formation, surface-aggregate formation, and polylayer formation. Some qualitative interpretations for the changes which take place in the adsorption layer in the presence of CDBACl are proposed and discussed.