Imidazole derivatives based on glycourils as efficient anti-corrosion inhibitors for copper in HNO3 solution: Synthesis, electrochemical, surface, and theoretical approaches

Abstract

Even though there are many synthesized structures that can be used to combat corrosion during the acid pickling process, the problem's persistence prompts modern corrosion scientists to seek deeper insights into the field by synthesizing more and more interesting moieties for practical applications and their applied capabilities against corrosion. The inhibition impacts of two imidazole derivatives fused ring based on glycourils, namely, Glycouril (tetrahydroimidazo[4,5- d ]imidazole-2,5(1 H,3 H)- dione) (3) and Dithioglycouril (tetrahydroimidazo[4,5- d ]imidazole-2,5(1 H,3 H)-dithione) (7)] on copper corrosion were investigated in stagnant aerated 1 M HNO 3 solutions at 25 °C. Surprisingly, there is no report on using glycouril (IMD-O) and/or dithioglycuril (IMD-S) as corrosion inhibitors for copper in acidic environment. The action of corrosion inhibiting of copper in 1 M HNO 3 for both compounds was explored by various electrochemical measurements, and the findings reveal that they all work as mixed-type corrosion inhibitors under the conditions that were studied. The results revealed the inhibitory effect of imidazole derivatives depends on their concentration. The examined imidazole derivatives displayed significant inhibitory efficiency (ex. 92.5 %) and played an important role in preventing copper corrosion in 1 M HNO 3 . The adsorption of the examined imidazole derivatives on copper surface in 1 M HNO 3 is followed Langmuir isotherm model. AFM investigation revealed a considerable improvement in the copper surface in the presence of imidazole derivatives, which protected the surface by forming an inhibitive coating over the copper surface. Furthermore, DFT calculations and Monte Carlo simulations on the active form of the synthesized imidazole derivatives were performed. The findings of the theoretical studies and electrochemical corrosion measurements are consistent with the microscopic results of the investigated imidazole derivatives based glycourils. The compounds in consideration could be a potential copper corrosion inhibitor in HNO 3 solutions, as they displayed superior corrosion inhibition properties to similar compounds and the inhibition efficiency increases in the following order IMD-O<IMD-S. • Imidazole derivatives based glycouril are investigated for the corrosion inhibition of copper in 1 M HNO 3 for the first time. • IMD-S is a good inhibitor for copper in 1 M HNO 3 at low concentration. • AFM results confirm those obtained by electrochemical measurements. • Theoretical studies confirm the performance of IMD-S.