Corrosion inhibition performance of 2-ethyl phenyl-2, 5-dithiohydrazodicarbonamide on Fe (110)/Cu (111) in acidic/alkaline solutions: Synthesis, experimental, theoretical, and molecular dynamic studies

Abstract

Herein, 2-ethyl phenyl-2,5-dithiohydrazodicarbonamide (2EPDCA) was synthesised and tested as a corrosion inhibitor for mild steel (MS) and copper (Cu) in 1 M HCl and 3.5% NaCl, respectively. Fourier transform infrared spectroscopy (FT-IR) and (NMR) nuclear magnetic resonance (1H, 13C) were used to identify the chemical structure. Both experimental and computational approaches have been conducted to evaluate inhibitor efficiency on both metal systems. The electrochemical results showed that the 2EPDCA inhibition efficiency for MS systems was 95% at 1 × 10−2 M, while in copper systems it was 97.5% at 1 × 10−2 M. The Langmuir adsorption isotherm was fitted using adsorption surface coverage data, and for inhibitor in both systems, the kind of adsorption was mixed (physisorption and chemisorption). Through scanning electron microscopy (SEM), EDX, and atomic force microscopy (AFM) tests, we have confirmed the presence of the inhibitor molecules on the metal surface in both systems. Quantum chemistry simulations indicate that the superior corrosion inhibition efficacy of 2EPDCA on copper compared to mild steel surfaces is attributable to the former's greater electron donating propensity on copper. The adsorption of 2EPDCA molecules on Fe (110) and Cu (111) surfaces was further verified by molecular dynamic simulations, with the former having a greater adsorption energy. The results indicate that the corrosion inhibitor was effective even in harsh conditions, and it can be thought of as a novel corrosion inhibitor for mild steel and copper that provides good protection.