Natural nutmeg oil as a green corrosion inhibitor for carbon steel in 1.0 M HCl solution: Chemical, electrochemical, and computational methods

Nutmeg oil was verified as a safe and green inhibitor for the corrosion of carbon steel type L-52 (CS L-52) in 1.0 M HCl solution through chemical, electrochemical, and computational studies. The outcome of these measurements confirmed that nutmeg oil was an effective inhibitor. The percentage inhibition efficacy (%IE) increased with increasing nutmeg oil concentration and decreasing temperature, reaching 94.73% at 500 ppm nutmeg oil. Polarisation curves revealed that the nutmeg oil acted as a mixed inhibitor, which was explained by the adsorption of nutmeg oil onto the surface of the CS. The adsorption process follows the Langmuir isotherm. Electrochemical impedance spectroscopy studies showed a single capacitive loop, indicating that the corrosion reaction was controlled by a charge transfer process. In addition, the thermodynamic parameters of the kinetic activation and adsorption process were calculated and interpreted, with results showing that the nutmeg oil acted as a pitting corrosion inhibitor through noticeable variation in pitting potential in the noble directions. This study also aimed to predict the inhibitory potency of the four molecular constituents of nutmeg oil through computational work, for which effort DFT and MC simulations were performed for the four inhibitor molecules. [Display omitted] •Nutmeg oil acts as a green excellent inhibitor for corrosion of carbon steel•Nutmeg oil considered as mixed type inhibitors•Adsorption of Nutmeg oil on the CS surface obeyed Langmuir isotherm.•Nutmeg oil acts as pitting corrosion inhibitor.•Theoretical study predicts that sabinene and α-pinene give better inhibition efficiency.