Electrochemical and Computational Evaluation of Fluconazole as a corrosion inhibition agent for carbon steel in acid chloride environments

Carbon steel corrosion inhibition in acidic environments was probed with fluconazole using a combined electrochemical (opencirciut potential-OCP, potentiodynamic polarization-PDP and electrochemical impedance spectroscopy-EIS) and theoretical approach (DFT calculations). Results reveal that fluconazole inhibits the corrosion of carbon steel, and the inhibition efficiency increases with extract concentration and exposure time. The maximum inhibition efficiency of 97.6% was recorded at 1.6 g/L at ambient temperatures. Electrochemical results indicated a drop in corrosion current density and a rise in charge transfer resistance on the addition of fluconazole to the system, which supports a mixed-type corrosion inhibitor. The adsorption of fluconazole was noted to be concordant with the Langmuir isotherm. The values of Gibbs free energy ranged from -11.85 to -17.75 kJ/mol, suggesting that the adsorption mechanism is predominantly via physisorption. Furthermore, theoretical calculations supported the electrochemical results, revealing that nitrogen and oxygen donor atoms in the fluconazole molecule act as key active centers for adsorption onto the carbon steel. The combined electrochemical and theoretical results establish fluconazole as a potent and eco-compatible carbon steel corrosion inhibitor in acidic environments.