N‐(4‐Chloromethylbenzyl)‐N, N‐dimethyldodecan‐1‐aminium Chloride: A Quaternary Ammonium Surfactant as Corrosion Inhibitor

Abstract This study used a quaternary surfactant, N‐(4‐Chloromethylbenzyl)‐N, N‐dimethyldodecan‐1‐aminium chloride (CMBDAC), as an excellent corrosion inhibitor of C1018 carbon steel (C1018 CS) in harsh 15 % HCl acidizing condition. CMBDAC was synthesized with an excellent yield and characterized by NMR, FTIR, and TGA. Gravimetric weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) studies were employed to measure the efficacy of CMBDAC. At a relatively low concentration of 15 ppm, CMBDAC surpassed 90 % inhibition efficiency, with a maximum inhibition efficiency of 99.25 % being reached just for 50 ppm of CMBDAC. The inhibitor showed an efficacy of 96.16 % even at a temperature of 60 °C via the WL technique, showing potential to be used as a high‐temperature corrosion inhibitor. The adsorption isotherm study revealed that CMBDAC followed Langmuir adsorption isotherm. The Gibbs free energy of adsorption ( was calculated to be −40.43 kJ mol −1 , indicating that CMBDAC was adsorbed via chemisorption. A very high value (1.68×10 5 L mol −1 ) of equilibrium constant ( ) suggested very strong adsorption of the inhibitor. PDP study disclosed that CMBDAC acted as a mixed‐type inhibitor. SEM‐EDX study demonstrated the adsorption of CMBDAC on the C1018 surface. Different DFT‐optimized parameters have been discussed in detail to support the superb inhibitory action indicated by CMBDAC.