Azole derivatives embedded in montmorillonite clay nanocarriers as corrosion inhibitors of mild steel

Azole derivatives such as 2-mercaptobenzothiazole (MBT) and 2-mercaptobenzimidazole (MBI) were introduced as corrosion inhibitors into the interlayer space of sodium montmorillonite clay (Na+-MMT). The corrosion protection behavior of mild steel in solutions containing MBT, MBI, MMT + MBT, MMT + MBI, Na+-MMT, and NaCl (3.5wt%) was evaluated using polarization and electrochemical impedance spectroscopy (EIS). Also, the release of penetrated species into the medium from the clay nanocarriers was evaluated using ultraviolet-visible (UV-Vis) spectroscopy. Small-angle X-ray scattering (SAXS) confirmed the insertion of MBT and MBI into the inner space of the clay layers and the interaction between two organic and inorganic phases. Scanning electron microscopy (SEM) was used to assess the morphology of the surface of the steel samples after the samples had been immersed for 24 h in the extraction solution. The corrosion protection in the solutions with clay nanocarriers containing MBT and MBI was better than that in solutions without MMT. The UV-Vis results showed that the release of MBI species from Na+-MMT nanocarriers in neutral pH was far lower than that of MBT species.