INHIBITION OF MILD-STEEL CORROSION IN 1N SULFURIC-ACID THROUGH INDOLE

The corrosion inhibition of mild steel in 1N sulphuric acid containing various concentrations of indole was studied in the temperature range of 25-70 degrees C through the use of potentiodynamic polarization cu rves. The indole was found to shift the corrosion potentials to positi ve values and to decrease the dissolution of mild steel and hydrogen e volution reaction. The effect, however, was more pronounced on the ano dic rather than the cathodic process. Indole did not generally affect the corrosion reaction mechanism (blocking effect). The reported activ ation energy (E(a)) values indicate that the inhibiting effect increas ed with the indole concentration. At temperatures of 25, 40, 55 and 70 degrees C the adsorption behaviour of the indole follows Temkin's iso therm with a standard free energy of adsorption of -54.49, -39.41, -43 .49 and -55.25 kJ/mol, respectively.