Adsorption and corrosion inhibition potentials of salicylaldehyde-based Schiff bases of semicarbazide and p-toluidine on mild steel in acidic medium : experimental and computational studies

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Authors

Olasunkanmi, Lukman O.
Idris, Aishat O.
Adewole, Adetola Henry
Wahab, Olaide O.
Ebenso, Eno E.

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Elsevier

Abstract

Experimental studies, supported by comprehensive density functional theory (DFT) and Monte Carlo simulation studies have been carried out on 2-(2-hydroxybenzylidene)hydrazinecarboxamide (SEMISCAD) and 2-((p-tolylimino)methyl)phenol (p-TOLUSCAD), to describe their corrosion inhibition potentials for mild steel in hydrochloric acid (HCl). The newly synthesized Schiff bases inhibit corrosion of mild steel in 1 M HCl, and their corrosion inhibition efficiencies increase with increase in concentration. Inhibition efficiencies of 79 % and 86 % were obtained for SEMISCAD and p-TOLUSCAD, respectively at 303 K and minute concentration (5 × 10-4 M). The results further revealed that p-TOLUSCAD could be an averagely efficient formulation to exhibit 50% inhibition efficiency, even at elevated temperature (343 K). Both compounds were found to inhibit corrosion at the anodic and cathodic sites on the steel, and they are therefore mixed-type inhibitors. Electrochemical impedance spectroscopy (EIS) data revealed the adsorptive nature of the molecules on the steel surface. SEMISCAD and p-TOLUSCAD inhibit steel corrosion by adsorbing at steel/HCl interface via physisorption and chemisorption mechanisms. Reactivity parameters predicted from DFT calculations suggested the involvement of protonated forms of the molecules in the inhibitive process, and p-TOLUSCAD as a potentially better corrosion inhibitor than SEMISCAD, which is also supported by the adsorption characteristics derived from Monte Carlo simulations.

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Keywords

Schiff base, Mild steel, HCl, Tafel polarization, Electrochemical impedance spectroscopy (EIS), Density functional theory (DFT), Monte Carlo simulation

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Citation

Olasunkanmi, L.O., Idris, A.O., Adewole, A.H. et al. 2020, 'Adsorption and corrosion inhibition potentials of salicylaldehyde-based Schiff bases of semicarbazide and p-toluidine on mild steel in acidic medium : experimental and computational studies', Surfaces and Interfaces, vol. 21, art. 100782, pp. 1-12.