The effect of two papaya seed extracts (infusion and acid extracts) on the corrosion of carbon steel in 1 mol L-1 HCl was examined. The efficiency for inhibiting the corrosion of C-steel in 1 mol L-1 HCl increased with the extract concentration and decreased slightly with the temperature. The inhibitory property of the extract is discussed in terms of the mechanism by which its components adsorb onto the C-steel surface decreasing the active surface area. This adsorption process obeyed a Langmuir adsorption isotherm. The infusion extract which presented more phenolic compounds than the acid extract showed higher inhibition efficiency. The apparent activation energy (Ea) for the dissolution of C-steel slightly increased when the infusion extract was used.
Keywords:
carbon steel; EIS; polarization; weight loss measurements; acid inhibition
