2017 Volume 66 Issue 8 Pages 268-272
In the previous studies, adsorption and corrosion inhibition of various anions and an organic cation inhibitor, tetrabutylammonium ion （C4H9）4N＋（ TBA＋） on the Fe surface in deaerated 1 M HClO4 have been discussed based on the hard and soft acids and bases principle. The present investigation deals with adsorption behaviors of adsorptive anions, Cl-, I- and SH- and also the anions plus TBA＋ on the Fe surface in 1 M HClO4. The values of the surface coverage, θ for the anions and/or TBA＋ were obtained from the electric double layer capacitances determined by impedance measurements. TBA＋, which has no unshared electron pair, was adsorbed on the surface by electrostatic interaction. The anions which hold unshared electrons rather chemisorbed than electrostatically adsorbed on the surface by the formation of a stable soft acid and soft base interaction. The highest values of θ for I- and SH-, classified into soft bases, were observed at the potentials near the zero-charge potential, Epzc because the Fe surface at Epzc behaves the softest acid. TBA＋ was adsorbed on the anion-chemisorbed Fe surface by electrostatic interaction, resulting in the high θ values.
