Inhibition of mild steel corrosion in 1N sulphuric acid through indole

Abstract

AbstractThe corrosion inhibition of mild steel in 1N sulphuric acid containing various concentrations of indole was studied in the temperature range of 25–70°C through the use of potentiodynamic polarization curves. The indole was found to shift the corrosion potentials to positive values and to decrease the dissolution of mild steel and hydrogen evolution reaction. The effect, however, was more pronounced on the anodic rather then the cathodic process. Indole did not generally affect the corrosion reaction mechanism (blocking effect). The reported activation energy (Ea) values indicate that the inhibiting effect increased with the indole concentration. At temperatures of 25, 40, 55 and 70°C the adsorption behaviour of the indole follows Temkin's isotherm with a standard free energy of adsorption of −54.49, −39.41, −43.49 and −55.25 kJ/mol, respectively.