Cynodon dactylon extract as eco-friendly corrosion inhibitor epoxy coating addition for mild steel

Ships frequently endure harsh sea conditions, subjecting their hulls to corrosion due to the extreme maritime environment. In the present work, an extract of Cynodon dactylon (CD) plant was studied as an eco-friendly anti-corrosion additive in epoxy coating. The epoxy coating performance was investigated after immersion in artificial seawater (ASW) through Open Circuit Potential (OCP), Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP), surface analysis and density functional theory (DFT). The corrosion studies were carried out in different time intervals (9, 30, and 40 days), and significant anti-corrosion performance was observed after longer immersion (30 and 40 days). The EIS results show that 1 wt.% additive of CD enhances the corrosion protection of epoxy coating. Tafel polarization results reveal that CD additive acted as a mixed type inhibitor and did not change the mechanism of corrosion reaction on the metal surface. The surface analysis reveals the addition of CD extract reducing coating pores and retarding the transfer of corrosive ions and water molecules through the coating. DFT calculations reveal the anti-corrosion mechanism might be due to the highest binding capability of carbohydrate derivative (EDM) with the metal surface.