Corrosion inhibition of carboxylate substituted amidrazone on mild steel in 3% NaCl medium: Electrochemical, DFT and molecular dynamics simulation studies

Abstract

The inhibitive effect of three synthesized amidrazone inhibitorsC6H4(2-COOH)NHN = C(COCH3)-NHC6H4(2-COOH) (1), C6H4(2-COOH)NHN = C(COCH3)-NHC6H5(2) and C6H5NHN = C(COCH3)-NHC6H4(2-COOH) (3)on mild steel in 3% NaCl solution at 25 ºC were evaluated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The X-ray show that two molecules of (1) isdimerize based on hydrogen bonding interactions. All experimental results demonstrate that these compounds are efficient inhibitors. The inhibition efficiencies(ηP%) increase with inhibitors concentration. At 1 × 10−4 M, the (ηP%) was 94.80%, 92.80% and 90.40% for 1, 2 and 3, respectively. The efficiency of inhibition is directly proportional to the concentration and the number of COOH on the amidrazone and inversely proportional to the temperature. Analysis of polarization curves showed that these compounds behaved as mixed-type inhibitors and their adsorption obeyed Langmuir model. Molecular dynamics and Quantum mechanical simulation approaches were utilized to rationalize the inhibition-efficiency of the investigated compounds.