Electrochemical, thermodynamic and quantum chemical studies of synthesized benzimidazole derivatives as corrosion inhibitors for N80 steel in hydrochloric acid

The inhibitive action of synthesized benzimidazole derivatives, namely: 2-(1-(morpholinomethyl)-1H-benzo[d]imidazol-2-yl)phenol (MBP), 2-(1-((piperazine-1-yl)methyl)-1H-benzo[d]imidazol-2-yl)phenol (PzMBP) and 2-(1-((piperidine-1-yl)methyl)-1H-benzo[d]imidazol-2-yl)phenol (PMBP) on corrosion of N80 steel in 15% HCl solution has been studied using weight loss measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. It was found that the inhibition efficiency of all the three inhibitors increases with increase in concentration of inhibitors and decreases with increase in temperature. The inhibitors, PzMBP, MBP, and PMBP show corrosion inhibition efficiency of 96.3, 94.4 and 92.9% respectively, at 200 ppm and 303 K. Polarization studies showed that the studied inhibitors are mixed type in nature. The results of the Fourier transform infrared (FTIR) and UV-visible spectroscopy provided evidence of iron/inhibitors interactions. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were performed for surface analysis of N80 steel samples in acid solution without and with inhibitors. The Density Functional Theory (DFT) was employed for quantum chemical calculations to correlate the experimental findings.