A highly-effective/durable metal-organic anti-corrosion film deposition on mild steel utilizing Malva sylvestris (M.S) phytoextract-divalent zinc cations

Abstract

For the first time, a metal-organic film with high anti-corrosion potency was constructed over the mild steel surface using Malva sylvestris (M.S) and zinc cations (Zn2+). The mild steel panels were immersed in the simulated seawater solution (3.5%wt. NaCl solution) containing different loadings of Zn:M.S inhibitors. The electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) measurements were performed at a different time step up to 240h. The potentiodynamic polarization test was carried out to determine the inhibitor's inhibition mechanisms. The synergistic inhibition impact of the Zn:M.S before and after immersion was analyzed by Ultraviolet-Visible (UV–vis) spectroscopy. The protective film formed on the surface was studied by the Fourier transform infrared (FT-IR), Raman, grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM), and contact angle (CA) techniques. The EIS results evidenced that applying various ratios of Zn:M.S resulted in more than 98% corrosion inhibition efficiency (IE), which was stable up to 240h. Meanwhile, the outstanding corrosion resistance of 170kΩ.cm2 in 300:700ppm Zn:M.S was recorded.