S-置換メルカプトカルボン酸誘導体による中性水溶液中の鉄の腐食抑制

抄録

S-substituted derivatives of mercaptocarboxylic acid, one of the chelating agents, were examined as inhibitors of iron corrosion in a simulated cooling water. Polarization measurement of 99.99% Fe electrode rotating at 2, 000rpm was carried out in the cooling water with and without the inhibitor by a potentiostat and a dynamic IR compensator. The most effective inhibitor used in the experiment was 3-(S-n-octylmercapto) propionic acid, I, which inhibited the anodic reaction to a great extent without a change in the cathodic reaction of corrosion process. The inhibitor I was found to form a stable protective film on the surface in a thickness corresponding to trimolecular layer. The polarized reflection infrared spectra of the surface film agreed with those for the reaction product of I and Fe³⁺, identified with Fe(III)(n-C₈H₁₇SCH₂CH₂COO)₃. It was concluded that the inhibition by this inhibitor was attributed to the formation of stable and insoluble film consisting of the product, probably the chelate compound of I on the iron surface.