Mild steel green inhibition by Ficus carica leaves extract under practical field conditions

Various electrochemical techniques were employed to study the effectiveness of aqueous Ficus carica (Fig. tree) leaves extract as green corrosion inhibitor for mild steel under field conditions containing 3.5% sodium chloride solution saturated with carbon dioxide. Optimum inhibition efficiency of 90% was obtained using 50 mg/L of inhibitor in the temperature range of 25–40 °C. The mode of action of Ficus carica leave extract as revealed by Polarization studies was shown to act as a mixed inhibitor. The adsorption isotherm of the adsorption of Ficus carica leaves extract on the steel surface was found to follow Langmuir adsorption isotherm. In order to assess the individual contribution of the different constituents of the extract theoretically, the adsorption of the four major organic constituents of Ficus carica leave extract on mild steel were modelled using density functional theory and quench molecular dynamic simulations. Among the four major Ficus carica leaves extract constituent investigated, Caffeoylmalic acid was found to make the most contribution to the overall inhibition action of Ficus carica leaves extract.