High-Efficiency Corrosion Inhibition of Benzene Ring-Containing Imidazoline Derivatives in Acidic Environments: Role of Benzene Ring Number and π-Electron Effects.

One of the reasons that corrosion inhibitors can work is due to the interaction between the benzene ring and the metal surface. Thus, investigating the impact of varying numbers of benzene rings on the corrosion inhibition efficiency is crucial. This study systematically examines the corrosion inhibition mechanisms of imidazole derivatives with different numbers of benzene rings on Q235 steel in 1.0 M HCl (OB represents one benzene ring, BB represents two benzene rings, and TB represents three). Electrochemical results indicate that the three inhibitors are mixed-type inhibitors, hindering both anodic dissolution and cathodic hydrogen evolution. Among them, the corrosion inhibition efficiency of TB at a concentration of 2.0 mM is 97.18%, which is superior to those of BB (94.45%) and OB (90.49%). Scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurement results demonstrate that the carbon steel surface after TB adsorption has the least corrosion products, the lowest roughness (Sa = 31.6 nm), and the highest hydrophobicity (contact angle = 84.62°). X-ray photoelectron spectroscopy (XPS) analysis confirmed that TB can more effectively inhibit the oxidation of iron. Theoretical calculations indicate that TB has a flatter adsorption configuration (MPP = 0.233 Å, SDP = 1.248 Å), stronger adsorption ability (Eads = 1585.46 kJ/mol), and a lower energy gap (ΔE = 1.809 eV), which favor larger and more stable adsorption. The ELF-π reveals that TB has a wider π electron delocalization range, facilitating the formation of more interfacial bonding and effectively blocking the corrosive medium. The results of RDG further confirm that TB has better adsorption capacity, alleviating concerns about increased steric hindrance due to the higher number of benzene rings. This paper explores the relationship between the number of benzene rings and corrosion inhibition performance, proposing that π electrons enhance corrosion inhibition efficiency, thereby providing theoretical support for the design of polycyclic corrosion inhibitors.