Anti-corrosive properties of two new green heterocyclic azole derivatives on C38 steel in 1 M (HCl) medium, experimental and theoretical study

Abstract

In 1.0 M HCl media, two newly component namely (1-Allyl-6-nitro-1H-indazole (1a) & 1-Ethyl-5-nitro-1H-benzimidazole-2-thiol (2b)) were used to inhibit corrosion of C38-steel. The activity inhibitor (IE%) of 1a & 2b was investigated using electrochemical, i.e., potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) & weight loss.The experimental results revealed that 1a & 2b successfully inhibited the C38- steel corrosion in C = 1.0 M// HCl solution. The IE(%) values produced by the three approaches were nearly identical, with the maximum value (97.5 %) obtained at T = 298 k of 2b.The high temperatures showed a negative effect on the corrosion inhibition efficiency of the tested inhibitor. Polarization methods revealed that the inhibitor behavior is of a mixed nature. The adsorption isotherm was also studied, and it was observed that 1a & 2b adsorbs on the C38- steel surface in agreement with the Langmuir isotherm, which indicated that both molecules adsorb on the metal’s surface, producing a protective layer that inhibits corrosion. The computational results demonstrate that the inhibitor formed a protective barrier against acid attack, preventing carbon steel from corrosion; these findings backed with the experimental findings. In addition, the regioselectivities experimentally observed were interpreted by Parr functions.

Keywords

• C38 steel
• Polarization
• Electrochemical impedance spectroscopy
• Chemical calculations (DFT and MDs)
• Parr functions