The inhibition effects of anion and cation inhibitors on corrosion of iron in an anhydrous acetonitrile solution of FeCl3

Abstract Corrosion of iron in an electrolytic anhydrous acetonitrile CH3CN (ACN) containing FeCl3 was investigated by polarization measurement and X-ray photoelectron and Fourier transform infrared reflection spectroscopies. The corrosion rate was markedly increased with the concentration of FeCl3. Cathodic and anodic processes of iron corrosion in the ACN solution of FeCl3 were reduction of Fe3+ to Fe2+ and Cl−-catalyzed iron dissolution, respectively. Bromide ion (Br−) mainly suppressed the anodic process of iron corrosion in the 0.01 M FeCl3 ACN solution by chemical adsorption on the surface. Hexadecyl-trimethylammonium ion C 16 H 33 N CH 3 + 3 (C16TMA+) was adsorbed on the negatively charged surface via an electrostatic interaction, resulting in inhibition of the cathodic process. An equimolar mixture of Br− and C16TMA+ suppressed both processes of iron corrosion in the 0.01 M FeCl3 ACN solution by joint adsorption on the surface, indicating the synergism of inhibition.