Corrosion Inhibition of API5LX60 Carbon Steel in CO2 Saturated 3.5% NaCl Solution by a Few Plant Extracts

Abstract

Plant extracts have been demonstrated to be effective, sustainable carbon steel corrosion inhibitors. In this paper, inhibitive characteristics of the plant extracts of Eclipta alba, Moringa oleifera, and Murraya koenigii were tested for API5LX60 steel in CO2 saturated 3.5% NaCl solution utilizing Gravimetric Weight Loss, Electrochemical Impedance Spectroscopy (EIS) and Polarization Studies (LPR and PDP). Eclipta alba showed a 90% inhibitory efficiency. The results implied that increased inhibitor concentration increases inhibition efficiency, and plant extracts act as mixed-type inhibitors. Further, Langmuir Adsorption isotherm asserts inhibitor adsorption by physisorption, and SEM and SEM-EDX verified film formation on the API5LX60 steel. Adsorption studies affirm physisorption with R2 value ~ 0.9. The results affirmed plant extracts as carbon steel corrosion inhibitors in CO2-saturated NaCl solution.