| Abstract: | The adsorption of TBP on Hg electrode from aqueous NaClO4 media has been studied using differential capacity and chronocoulometric measurements. TBP adsorbs in two steps, the first corresponding to a flat and second to a perpendicular orientation. Both orientations were observed in the entire investigated potential range. The maximal measured surface concentration (Γmax) of TBP reaches a value of 1.55×10?10 mol cm?2, which corresponds to the theoretical value for densely packed molecules in perpendicular orientation. Γ value of the first isotherm step plateau is about 7 to 15% smaller than Γmax and decreases strongly at potentials more negative than ?0.9 V due to the repelling of negative charges between the electrode and the phosphate group. The standard Gibbs energy of adsorption was found to reach the value of ?34 kJ mol?1. |
