Electrochemical, surface and theoretical investigations of a new tri-tolyl imidazole designed for corrosion inhibition of carbon steel in normal hydrochloric acid medium
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Original research


Throughout this work, it is intended to evaluate the effect of a new ((4RS,5SR)-2,4,5-tri-p-tolyl-4,5-dihydro-1H-imidazole (4T-C) on Carbon Steel (C-steel) corrosion inhibition in 1 M HCl medium. For this purpose, potentiodynamic polarization measurements and Electrochemical Impedance Spectroscopy (EIS) were realized. It could be perceived that the inhibitor concentration increase led to substantial corrosion level drop of C-steel in the harsh medium, with inhibitive efficiency value reaching 96 % at 10−3 M inhibitor concentration. The polarization curves showed that the inhibitor 4T-C operated as a mixed cathodic and anodic type inhibitor. The Nyquist diagrams illustrated that increasing 4T-C’s amount in solution occasioned an increase in polarization resistance values, implying an increase of the inhibitory efficiency and a decrease of the double layer capacity. SEM and UV–Vis. spectroscopy have been utilised to specify the impact of the inhibitor’s existence on the superficial condition of the C-steel in the harsh solution. Temperature impact of the 4T-C molecule on the corrosion conducts of C-steel in 1 M HCl at the inhibitor’s optimal amount of 10−3 M has been explored in the T range of 303–333 K. It could be stated that inhibitive efficiency was not significantly affected by the temperature rise. The Langmuir isotherm model was found to govern 4T-C adsorption on C-steel surface. Energy, enthalpy and entropy of activation were calculated and discussed. The Arrhenius law was used to calculate the adsorption free energy. The chemisorption of 4T-C on the C-steel surface was confirmed by a free adsorption energy of −44.04 kJ/mol. To support the experimental results, the investigated inhibitor molecule was optimized using B3LYP/6–31+ G(d,p) level of theory and Molecular Dynamic Simulation (MDS). The calculation was apprehended in aqueous medium. The global and local chemical reactivity describing parameters were determined and analysed.

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