Synergistic corrosion inhibition of A3 steel in hydrochloric acid by Sodium dodecyl sulfate and 2‐mercaptopyridine: Experimental and theoretical calculations

The inhibition performance of sodium dodecyl sulfate (SDS) and 2-mercaptopyridine (2MP) corrosion inhibitors on A(3) steel in 0.5 M HCl increase with increasing of the inhibitor concentration (50-200 mg L-1). SDS and 2MP inhibitor follow Freundlich adsorption isotherm and Langmuir adsorption isotherm, respectively. These two inhibitors exhibit good synergistic inhibition effect on the corrosion of A(3) steel in 0.5 M HCl solution when the mass ratio of SDS:2MP is 1:4. Gibbs free energy of the mixture is lower and the mixture exhibit good adsorption stability. 2MP molecule are adsorbed on metal surface through N atom and sulfhydryl group. SDS molecule interacts with metal through O atoms while the alkyl chain pointing to the test solution. This adsorption configuration is beneficial to the formation of the inhibitor film, the migration of the corrosive particles to the metal surface was hindered and thus the metal surface was protected.