Interaction of 12-aminododecanoic acid with a carbon steel surface: Towards the development of ‘green’ corrosion inhibitors

The inhibiting effect of 12-aminododecanoic acid (AA) on corrosion of carbon steel (CS) in CO2-saturated hydrochloric acid was investigated. It was found that AA acts as a mixed-type inhibitor, yielding a maximum inhibition efficiency of 98.1 ± 0.1%. The mechanism of its corrosion inhibition is by formation of a self-assembled monolayer (SAM), which presents a tight hydrophobic barrier imposed by the (–CH2)11 chain. In-situ PM-IRRAS measurements revealed that the SAM is amorphous. The SAM formation process was found to be spontaneous and reversible. The corresponding standard Gibbs energy of AA adsorption on CS was calculated to be −28 kJ mol−1.