Effect of the deaeration on the adsorption of some cationic surfactants at the mercury/electrolyte solution interface

The effect of the deaeration on the adsorption of three cationic surfactants cetyldimethylbenzylammonium chloride (CDBACl), cetyltrimethylammonium bromide (CTAB) and octadecyltrimethylammonium bromide (OTAB) at the mercury/electrolyte solution interface is studied. The deaeration is studied using either nitrogen or helium and the effect of deaeration process and time is also studied. In all cases an effect of the deaeration time is found which is mainly observed at potentials where a condensed film is formed. Capacity–time curves at the potentials where the film is formed show a nucleation and growth mechanism with induction time that depends on the deaeration time. The deaeration slows down the kinetics of the film formation but does not change the equilibrium capacitance value of the film. The decrease of the dissolved gas from the water that perturbs its structure is perhaps the main reason for the behaviour observed during the adsorption of these surfactants.