Influence of the multilayer adsorption ofn-octanol andn-decanol on electrooxidation of the radical anion of 3-nitrophthalic acid

The electrooxidation of in situ produced electrolytically radical anion of 3-nitrophthalic acid in various water—ethanol solutions containing 0.5 M NaCIO4, 0.05 M NaOH and inhibitor has been studied. The inhibition of the electrode kinetics in the presence of n-octanol and n-decanol, used as inhibitors, at relative concentrations not exceeding c/cs ≤ 0.5 could be interpreted in terms of the competitive monolayer adsorption of reactant, inhibitor and solvent on the electrode surface. At c/cs > 0.8, on the capacitance-potential curves, a subtle minima caused by formation of two layers adsorbed on the mercury electrode were observed. The kinetics of the electrooxidation of the 3-nitrophthalic acid anion radical was additionaly influenced by this multilayer. An equation which describes the inhibition of the electrode process by two adsorbed layers of inhibitor is presented and used in the estimation of the surface coverage in the second layer.