Electrochemical measurements and semi-empirical calculations for understanding adsorption of novel cationic Gemini surfactant on carbon steel in H 2 SO 4 solution

A novel imidazolium-based cationic Gemini surfactant (GS) was synthesized, characterized and evaluated as a corrosion inhibitor for carbon steel in 0.5 M H 2 SO 4 using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results revealed that this Gemini surfactant can act as an effective mixed-type inhibitor ( η p  ∼ 90%) for carbon steel via adsorption of its molecules on the metal surface according to Langmuir adsorption isotherm. The synthesized GS showed a good synergistic inhibitory action with Ce 3+ cations and Iˉ anions in 0.5 M H 2 SO 4 medium ( η p  ∼ 93% and 95%, respectively). Thermodynamic activation parameters for the dissolution process of carbon steel in blank and inhibited sulfuric acid solution were calculated and discussed. A suitable equivalent circuit was used to analyze the experimental EIS data and modeling the inhibition process. Quantum chemical calculations have revealed that the tested Gemini surfactant can interact with Fe surface through electron transfer from the metal atom to surfactant molecule.