Exploring p-dimethylaminocinnamaldehyde thiosemicarbazone for the surface protection of mild steel in acidic media

Abstract

In recent years, the pursuit of efficient organic corrosion inhibitors (C-Inhs) for mild steel (MS) has focused on Schiff bases due to their strong adsorption ability and structural versatility. For the first time, we investigate the corrosion inhibition performance of 1-(-3-(4-(dimethylamino)phenyl)allylidene)thiosemicarbazide (DMAPAT) for C1010 MS in 1 M HCl. An in-depth investigation by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight degradation analysis was employed to evaluate DMAPAT's anticorrosion performance. Electrochemical analysis revealed DMAPAT as a mixed, pickling-type inhibitor, improving corrosion resistance by increasing charge transfer resistance (R_ct). The gravimetric analysis confirmed the remarkable inhibition efficiency (IE) of DMAPAT reaching 97.54% at 303.15 K and 97.01% at 333.15 K at a low concentration of 0.5 mM. The enhanced corrosion inhibition performance is attributed to strong adsorption through both physisorption and chemisorption, following the Langmuir adsorption isotherm, where the presence of π-electrons and electron-rich heteroatoms promotes the formation of a stable protective film. Surface analyses using scanning electron microscopy (SEM), 3D profilometry, X-ray diffraction (XRD), and contact angle measurements confirmed structural changes and enhanced hydrophobicity. Additionally, density functional theory (DFT), molecular dynamics (MD), and Monte Carlo (MC) simulations provided insights into the electronic structure and adsorption behavior of DMAPAT, supporting its excellent corrosion resistance properties.