Corrosion Inhibition of Carbon Steel in HCl Solution by Aqueous Brown Onion Peel Extract

The effect of aqueous brown onion peel extract on the corrosion process of carbon steel in 1 mol L-1 HCl was examined. The electrochemical results, including the displacement of the corrosion potential and the inhibitory action in both anodic and cathodic polarization curves showed that the examined extract acted as mixed-type inhibitor. The results of the electrochemical impedance measurements showed that the Rct values increased in the presence of inhibitor reaching 94% of inhibition efficiency in the presence of 300 mg L-1 of the extract. The inhibition efficiency of C-steel in 1 mol L-1 HCl increased as the temperature increased and the apparent activation energy (Ea) of C-steel dissolution decreased in the presence of the extract, which suggest a strong chemisorptive bond between the components present in the onion extract and the metal surface. The extract analysis showed few volatile compounds with 3(2H)-Furanone, 2-hexyl-5-methyl- as the major volatile compound and a nitrogenous base (5-octadecyl-pyrimidine-2,4,6-trione) which may play an important role in the inhibition process.