Corrosion inhibition of Schiff base and their metal complexes with [Mn (II), Co (II) and Zn (II)]: Experimental and quantum chemical studies

Abstract

The synthesis, characterization, and examination of anti-corrosion performance of 2-furaldehyde semicarbazone Schiff base (FSC) complexes of cobalt (II), zinc (II), and manganese (II) on XC38 carbon steel immersed in 1 M HCl solution are performed using experimental investigations and quantum chemical simulation approaches. The theoretical approach used were DFT calculations and MC simulation. The inhibition effect was also studied by electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). Electrochemical testing results show that these chemical compounds are particularly powerful inhibitors, which FSC-Mn provides a considerable inhibition of 91.48%at 500 ppm. The results also demonstrate that the inhibition effect of the four inhibitors increased with increasing inhibitor concentration, revealing that these compounds adsorb significantly to the steel surface. The scanning electron microscopy (SEM) analyses indicated that FSC and its complexes adsorbed onto the surface of XC38 carbon steel by forming a barrier between the inhibitors and the vacant d-orbital of iron. Quantum investigations were consistent with experimental findings on the four inhibitors’ capacity to prevent XC38 carbon steel from corroding in 1 M HCl, which were also proven effective as cathodic and anodic type inhibitors, displacing water molecules from mild steel, and producing heterogeneous coatings on the XC38 carbon steel surface to defend against corrosion.