Comprehensive Analysis of a Thiazole-Substituted Corrosion Inhibitor's Impact on N80 Carbon Steel in Acidic Conditions: Integrating Computational Predictions with Experimental Verifications

The present investigation elucidates the effectiveness of a newly developed organic inhibitor, namely 6,6-diphenyl-2,3-dihydroimidazo[2,1-b]thiazol-5(6H)-one (PHIT) in inhibiting the corrosion of N80 carbon steel (N80-CS) in 15 wt.% HCl at 303 K. An integrative approach combining theoretical insights through Density Functional Theory (DFT) and molecular dynamics (MD) simulations with empirical data derived from a suite of analytical techniques (namely, weight loss measurements, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and scanning electron microscopy (SEM)), was employed to assess the corrosion inhibition performance. The research identified the thiazolone fragment as the predominant site of activity within the PHIT molecule. According to EIS results, a significant reduction in the effective double-layer capacitance from 174 (blank) to 36.17 μF/cm2 was registered following the addition of 5×10-3 mol/L PHIT to the HCl medium. Moreover, at a low concentration of 10-4 mol/L, the inhibition efficiency reached a maximum of 95%. The immersion time had a significant effect on the inhibitor’s polarization resistance, peaking at 48 h (596 Ω cm2), then experiencing a minor reduction at 72 h (457 Ω cm2), in comparison to the blank measurement at 0.5 h (231 Ω cm2). Besides, the inhibitor demonstrated a high degree of effectiveness across various temperatures with a slight decrement in efficiency from 96.5% at 303K to 94% at 363K. PDP results confirmed the tested compound as an anodic-type inhibitor. These results affirmed the potential of PHIT as a highly efficacious organic inhibitor for N80-CS in acidic conditions, encouraging further development of its derivatives.