Corrosion mitigation of carbon steel using pyrazole derivative: Correlation of gravimetric, electrochemical, surface studies with quantum chemical calculations

The current paper revolves around the conduct of newly synthesized eco-friendly pyrazole derivative, N-((3,5 dimethyl-1H-pyrazol-1-yl)methyl)-4-nitroaniline (L5), as corrosion inhibitor for carbon steel (CS) in molar hydrochloric acid (1M HCl) solution. Both chemical and electrochemical techniques, namely weight loss measurements (WL), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were used to evaluate the efficiency of L5 molecule, as well as quantum-chemical methods. The organic compound was confirmed to be a good anti-corrosion compound with a maximum inhibition efficiency (IE%) of 95.1% at 10-3 M. In accordance to PDP outcomes, the inhibitor L5 acts as a mixed-type inhibitor. Assessment of the temperature influence evinces that L5 is chemisorbed on CS. The adsorption of L5 on CS surface appears to follow the Langmuir model. Scanning Electron Microscopy (SEM-EDX) and UV–visible disclose the constitution of a barrier film limiting the accessibility of corrosive ions into CS surface. Theoretical studies were executed to support the results deriving from experimental techniques (WL, PDP and EIS). Furthermore, theoretical studies were carried out utilizing density functional theory (DFT) and molecular dynamics simulation (MDS) to investigate the most reactive locations of the L5 molecule and its adsorption process.