Eco-Friendly Plant Extract of Medicago sativa (Alfalfa) as Corrosion Inhibitor for Carbon Steel in Marine Environment

Abstract

The inhibiting effect of an Alfalfa extract in a corrosive medium (3.5% NaCl + 16 ppm Na₂S) on the corrosion of carbon steel was studied by the mass loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results showed that the inhibition efficiency, increases with an increase in the extract dose but decreases at higher temperatures. The obtained results indicated that the investigated extract is physically adsorbed on the carbon steel surface and follows the Temkin adsorption isotherm. The polarization data revealed that this extract acts as mixed type inhibitor. The surface morphology was tested using atomic force microscope. The results obtained from different techniques are in good agreement.