Novel Silicon-based schiff-base as corrosion inhibitor for anti-corrosion behavior of API 5L Grade B in 1M HCl

Abstract

The efficiency inhibition of the novel Schiff-base compound named o-(2-(12-(2-((((E)-(5- (hydroxymethyl)furan-2-yl)methylene)carbamothioyl)oxy)ethyl)-1,7,9,15-tetraoxa-4,12-diaza-8- silaspipiro[7.7]pentadecan-4-yl)ethyl)(5-(hydroxymethyl)furan-2-yl)methylene)carbamothioate, for corrosion of API 5L B in aqueous media of 1 M HCl was assessed. The synthesized compound was characterized by 1H NMR, 13C NMR and FT-IR spectroscopy. Using electrochemical impedance espectroscopy, potentiodynamic polarization, atomic force microscopy, scanning electron microscopy and quantum chemical measurements, the behavior and corrosion protection mechanism of carbon steel was studied under the mentioned conditions. The optimizations of the geometry, was conducted utilizing the density functional theory methods. Measurements of potentiodynamic polarization showed the action of the intended inhibitor as a mixed inhibitor in the acid solution. As shown by the electrochemical impedance results, the charge transfer resistance was elevated and the double layer capacity showed a reduction by adding the inhibitor. According to the study of adsorption isotherms, the inhibitor adsorption in the solution on the steel surface matching with the Langmuir adsorption isotherm. The adsorption was a spontaneous process and the amount of the adsorption free energy reflected the chemical and physical occurrence of adsorption. Using atomic force microscopy and scanning electron microscopy investigations, the result of electrochemical methods was confirmed. The Monte Carlo and Molecular Dynamics simulation proved the flat adsorption of the inhibitor just on one side of the molecule, leading to exposing its adsorption centers to the steel surface. They were rather high, and it was in agreement with the experimental data acquired to date.