Inhibition of the corrosion of iron heritage objects after treatment with long-chain monocarboxylic acids in ethanolic solutions

Ethanolic solutions of long-chain carboxylic acids with the general formula CH3(CH2)n−2COOH (12 ≤ n ≤ 16; HC12, HC14, and HC16) are used to coat iron heritage objects. Prior to treatment, the iron surface is passivated electrochemically in a borate buffer solution to obtain a ferrihydrite film that simulates the natural oxide layer on real artefacts. The coatings are characterized by Fourier transform infrared spectroscopy. The corrosion inhibition properties are examined by using linear sweep voltammetry and electrochemical impedance spectroscopy in a corrosive solution to simulate the corrosive environment in museums with uncontrolled conditions. The results showed that these carboxylic acids form a protective barrier and inhibit iron metal corrosion and that HC14 has the highest inhibition efficiency.