Synthesis and Characterization of New Macromolecular Epoxy Resin as an Effective Corrosion Inhibitor for C38 Steel in 1 M HCl Medium: Electrochemical Insights, Surface Morphological and Computational Approaches

Many efforts have been made recently to develop solutions to corrosion problems. The current study was focused on synthesizing a new epoxy compound called Tetraglycidyl orthophenyl diamine (TGOPDA) and using it as a powerful inhibitor of carbon steel C38 in 1 M HCl for the first time. Furthermore, the title molecule’s structure was discovered utilizing Fourier transform infrared spectroscopy. The corrosion inhibition and adsorption behavior of TGOPDA onto C38 surface was then evaluated in 1 M HCl utilizing the weight loss measurements, thermodynamic/kinetic parameters and electrochemical techniques (Open circuit potential), Potentiodynamic polarization (PDP) and Electrochemical impedance spectroscopy (EIS)). Additionally, surface morphology (SEM/EDX) with computational tools such as: DFT (Density functional theory) calculations, RDF (Radial distribution function) analysis, MC (Monte Carlo) and MD (Molecular dynamic) simulations were combined to get insights into our inhibitor adsorption on C38 steel surface. The EIS tests demonstrated that the addition of TGOPDA improved the effectiveness of C38 steel inhibition, reaching about 95.27% at 5 mM. Furthermore, the PDP investigation demonstrated that the TGOPDA worked via a mixed-type mechanism. According to the thermodynamic kinetic characteristics, TGOPDA adsorption on C38 steel surface sites follows the Langmuir adsorption isotherm. SEM and EDX studies revealed the production of an adsorbed inhibitor protective layer on the C38 steel surface. The computational investigations based on DFT, MD, MC, and RDF proved that TGOPDA adsorbed on the metal surface formed a corrosion-protective barrier film.