Characterization and Experimental and Computational Assessment of Kola nitida Extract for Corrosion Inhibiting Efficacy

Kola nitida (KN) extract was assessed for its ability to hinder corrosion of mild steel in 0.1 M HCl solution by means of gravimetric and electrochemical tests. KN extract was found to efficiently retard mild steel corrosion in this system, with the effect becoming more pronounced as KN extract concentration increased and slightly subdued as immersion time lengthened. From the polarization and impedance results, KN extract was seen to affect both the cathodic and the anodic reactions following adsorption of organic species from the extract on the metal/solution interface. The presence of such organics was confirmed by UV–visible spectrophotometry and gas chromatography–mass spectroscopy analyses. Selected constituents of the extract were modeled in order to assess their adsorbability using the density functional theory (DFT) and revealed remarkably high interaction energies, which corroborate the experimental findings