Red Algae Halopitys Incurvus Extract as a Green Corrosion Inhibitor of Carbon Steel in Hydrochloric Acid

The inhibitor of corrosion effect of isopropanol extract of a red algae Halopitys incurvus ( HIE ) on carbon steel in HCl 1 M was studied by weight loss method, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results revealed that this extract acted as an inhibitor in the acid medium. The inhibition efficiency increases with the increasing concentration. The maximal value of inhibition efficiency is 81.86% at 600 mg/l at 298 K. The polarization curves indicate that the HIE acts as a mixed-type inhibitor. The charge transfer resistance increases on the other hand the double-layer capacity decreases with the increasing concentration of HIE . The temperature influence was studied in the range of 298–328 K, and the results obtained reveal the decrease of the inhibition efficiency with temperature. Both kinetic and thermodynamic parameter of adsorption allows us to suggest physical adsorption of this inhibitor on the metal. The adsorption of HIE extract on the carbon steel follows Langmuir isotherm adsorption.