The anticorrosive efficacy of newly synthesized pyrido-bis(benzo[b]azoninone) analogs on carbon steel under sweet corrosive environments: A combined empirical and theoretical approaches

This study presents a novel and eco-friendly approach to address the critical challenge of carbon steel corrosion in CO₂-rich saline environments, a significant concern in the oil and gas industry. We report the efficient synthesis of a new class of corrosion inhibitors: pyrido-bis(benzo[b]azoninone) (PSA) analogs. These PSA derivatives were conveniently prepared using a one-pot, three-component reaction under microwave irradiation, with their chemical structures confirmed by ¹H and ¹³C NMR spectroscopy. The effectiveness of the synthesized PSA derivatives was then evaluated for their ability to protect N80 steel in a CO₂-saturated 3.5 % NaCl solution. The results were impressive, with the PSA demonstrating outstanding corrosion inhibition efficiencies ranging from 94.6 % to 96.2 %. Electrochemical measurements (potentiodynamic polarization and electrochemical impedance spectroscopy) revealed that the PSAs act as mixed-type inhibitors, adhering to the Langmuir adsorption isotherm on the steel surface. X-ray photoelectron spectroscopy (XPS) analysis provided further evidence, confirming the formation of a protective barrier on the steel by the adsorbed PSA. Theoretical support for these findings comes from density functional theory (DFT) calculations, which establish a connection between the theoretical predictions and experimental observations. Additionally, MC simulations further corroborated the effectiveness of PSA adsorption on the iron (110) surface. In conclusion, this research offers groundbreaking insights into developing exceptionally efficient and eco-friendly corrosion inhibitors using novel PSA analogs. This approach holds significant promise for mitigating the challenges the oil and gas industry faces in protecting steel infrastructure in harsh CO₂-rich environments.