Steel-alloy surface protection against saline attacks via the development of Zn(II)-metal-organic networks using Lemon verbena leaves extract (LVLE); Integrated surface/electrochemical explorations

Abstract One way to reduce the steel dissolution/corrosion rate in saline (NaCl) media and increase its anti-corrosion durability is by introducing green inhibitors (plant sources). Also, the anti-corrosion performance of the green inhibitors in saline media is not good lonely. Adding metal cations such as Ce and Zinc would be helpful for reaching high anti-corrosion efficiency. In this study, the synergistic effect of Lemon verbena leaves extract (LVLE):Zn cations on the mild steel (MS) corrosion in NaCl electrolyte was explored by electrochemical and morphological methods (i.e. EIS and DC-polarization). The samples' surface microstructure was surveyed by FE-SEM, AFM, GIXRD, and EDS techniques. The results of FE-SEM and AFM displayed that the intact protective layer was formed over the MS surface in the case of applying 200–600 ppm LVLE: Zn over MS surface. The outcomes of electrochemical methods illustrated that the anti-corrosion performance of MS in 3.5% saline solution was improved where the total resistance raised to 37,600 Ω.cm2 after 24 h of immersion (the inhibition efficiency and synergistic index were about 95% and 50%, respectively) via controlling both anodic and cathodic reactions. The FT-IR spectra and UV-Vis results showed the prosperous interaction between the LVLE and Zn after combination. In addition, the Raman test results displayed the presence of both D and G bands after adsorption of LVLE:Zn complexes on the metal surface.