Novel naphthybithiophene derivatives as corrosion inhibitors for carbon steel in 1 M HCl: Electrochemical, surface characterization and computational approaches

Abstract

Corrosion suppression performance and adsorption attitude of 5′-(naphthalen-2-yl)-[2,2′-bithiophene]-5-carboxamidine hydrochloride salt (MA-1341), 5′-(isoquinolin-4-yl)-[2,2′-bithiophene]-5-carboxamidine hydrochloride salt (MA-1348) and 5′-(4-chlorophenyl)-2,2′-bithiophene-5-carboxamidine hydrochloride salt (MA-1340) for the inhibition of the carbon steel (C-steel) surface dissolution in 1.0 M hydrochloric acid solution were investigated using different techniques. A chemical technique (weight loss method), electrochemical techniques (including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopic (EIS) analysis) and theoretical studies (Density Functions Theory (DFT)) were performed. Moreover, the adsorption of these inhibitors on the surface of C-steel was affirmed using Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). The surface morphology of the C-steel was examined using Scanning Electron Microscopy (SEM). The obtained results revealed high inhibition performance resulting from the adsorption of these compounds on the C-steel surface, developing a shielding layer that prevents the dissolution of the metal in the acidic solution. The inhibition efficiency (%η) found to be increased with growing the inhibitor dose and solution temperature giving the higher efficiency 95.14 %, 93.55 % and 91.05 % for MA-1348, MA-1341 and MA-1340, respectively at the optimum concentration 30 × 10−6 mol/L and temperature 328 K. The studied inhibitors were chemically adsorbed on the steel surface and obeyed the Langmuir adsorption isotherm. The quantum computations and Monte Carlo simulation methods were used to prove the inhibition mechanism of naphthybithiophene derivatives at the molecular level.