Green-synthetized -amino--carbethoxy ethyl acrylates as corrosion inhibitors for mild steel in acid media: Experimental performance evaluation and atomic/molecular-level modeling

Two beta-amino acrylate derivatives were synthesized through a solvent- and heating-free mechanochemical procedure. Those substances were tested as corrosion inhibitors for mild steel in acidic environment (1 mol/L HCl). Weight Loss Study demonstrated that both molecules mitigate corrosion with 85 and 90 % efficiencies. Electrochemical experiments proved that the corrosion mechanism is charge transfer and that the presence of EOAB and DBMM at any tested concentration in the electrolyte significantly increases the polarization resistance and lowers the corrosion density current. This phenomenon is due to the adsorption of the molecules on the mild steel surface, leading to the formation of a protection film that prevents the corrosion reaction, as suggested by Atomic Force Microscopy topographic images. The self-consistent-charge density-functional tight-binding method (SCCDFTB) revealed that their adsorption strength on the iron surface followed well the corrosion inhibition performance. Both inhibitor molecules formed covalent bonds with iron atoms as evidenced from stable adsorption geometries and projected density of states. Quantum chemical parameters seem to fail in predicting the experimental performance. Outcomes from the present study confirmed the fact that an additional functional group would lead to an increased inhibition performance is not a granted correlation.