Insight into the corrosion inhibition of novel macromolecular epoxy resin as highly efficient inhibitor for carbon steel in acidic mediums: Synthesis, characterization, electrochemical techniques, AFM/UV-Visible and computational investigations

The present work aimed to investigate the corrosion behaviour of carbon steel (CS) in hydrochloric acid and sulfuric acid solutions (1 MHCl and 0.5 M H2SO4) in the presence of new macromolecular epoxy resin synthesized namely N2.N4.N6-tris(2-(oxiran-2-yl methoxy) ethyl)-N2.N4.N6-tris(oxiran-2-yl methyl)-2. 4.6-triamine-1.3.5-triazine (ERT). This corrosion protection activity was detected by utilizing various methods including electrochemical impedance spectroscopy (EIS), polarisation curve (PC) measurements, atomic force microscope (AFM) analysis, global quantum chemical descriptors computations (GQCDs) and molecular dynamics (MDs) simulation. The corrosive solutions after corrosion tests have been identified by UV-visible. The obtained results, indicating that the compound as mixed type inhibitor significantly reduced the corrosion rate of CS due to the formation of a stable protective film on the metal surface. As confirmed by EIS, AFM and theoretical studies, chemically adsorbed ERT molecule is a better corrosion inhibitor with higher corrosion efficacy of about 95.5% in HCl and 98% in H2SO4 at room temperature. Langmuir isotherm model is the most acceptable one to describe the ERT molecules adsorption on the surface of CS. Protection mechanisms were supported by GQCDs, Fukui functions, dual local descriptors, radial distribution function and MDs simulation. These theoretical calculations support the results obtained experimentally to qualify ERT as a very effective inhibitor against the corrosion of CS in both acidic media. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the corrosion behavior of carbon steel in hydrochloric acid and sulfuric acid solutions in the presence of a newly synthesized macromolecular epoxy resin. The results showed that the compound significantly reduced the corrosion rate of carbon steel by forming a stable protective film on the metal surface, with corrosion efficiencies of about 95.5% in HCl and 98% in H2SO4. Langmuir isotherm model was the most suitable to describe the adsorption of the epoxy resin on the surface of carbon steel. Theoretical calculations supported the experimental results, confirming the epoxy resin as a highly effective inhibitor against carbon steel corrosion in acidic media.