Synergistic effect of Black cumin extract and zinc cations on the mild steel corrosion resistance improvement in NaCl solution; Surface and electrochemical explorations

Corrosion inhibitors are used to enhance the anti-corrosion properties of mild steel in corrosive environments. In this study, for the first time, a hybrid corrosion inhibitor based on Black cumin extract (BCE) and zinc cations was employed to mitigate the mild steel dissolution rate in NaCl media. The inhibitive film fabricated on the metal surface in the presence of BCE was characterized by scanning electron microscopy equipped with energy dispersive spectroscopy (SEM/EDS), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, Grazing Incidence X-ray Diffraction (GIXRD), and UV-vis tests. Also, the electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization tests were engaged in 3.5 wt%. NaCl solution to study the pro-tection performance of the metal in the presence of inhibitors. Due to the fabrication of inhibitive film, the anti-corrosion properties of the mild steel are significantly enhanced in the presence of organic/inorganic corrosion inhibitors. The creation of the inhibitive film in the presence of hybrid corrosion inhibitors was proved through SEM analysis and electrochemical testing. Electrochemical tests proved a synergistic effect between the selected inhibitors. The inhibitor efficiency for hybrid corrosion inhibitor was calculated at about 95 %, and 90 % in EIS and polarization tests, respectively. FT-IR, Raman, and XRD tests' outcomes proved the complex inhibitors' film formation over the metal substrate.

Automated summary

This study employed a hybrid corrosion inhibitor based on Black cumin extract and zinc cations for the first time to mitigate the dissolution rate of mild steel in NaCl media. The inhibitive film formed in the presence of the inhibitors significantly enhanced the anti-corrosion properties of the mild steel.