The Corrosion Inhibition Performance of Novel and Efficient Imidazoline Derivative Corrosion Inhibitors on N80 Steel in 1 mol/L HCl

ABSTRACT Two novel imidazoline derivatives—benzoic acid imidazoline (BJS) and thiopheneimidazole (SZ)—were designed and synthesized as corrosion inhibitors for acid washing by introducing functional groups onto the imidazoline skeleton. Using raw materials like benzoic acid, 2‐thienoic acid, cinnamaldehyde, and diethylenetriamine, synthesis involved amide formation and cyclization. Their corrosion inhibition for N80 steel in 1.00 mol/L HCl was evaluated via weight loss, electrochemical tests, surface analysis, and theoretical simulations. At 800 mg/L, the inhibition efficiencies of BJS were 89.7% (EIS), 91.4% (Tafel), and 91.41% (weight loss), while those of SZ reached 91.8%, 92.5%, and 92.02%, respectively. Both are mixed‐type inhibitors, mainly suppressing the cathodic reaction, and follow Langmuir adsorption, indicating spontaneous adsorption on N80 steel. XPS and SEM/EDS confirmed that the addition of corrosion inhibitors led to the formation of a protective film on the N80 steel surface, preventing further corrosion by corrosive media. DFT calculations identified active sites: for BJS, the phenyl group and N atoms in the imidazole ring; for SZ, N atoms in the imidazole/benzene rings and the S atom in the thiazole ring. MD simulations supported the adsorption behavior. The excellent inhibition of BJS and SZ in HCl is attributed to a stable protective film on the steel surface, reducing charge transfer in the corrosion system.