Experimental and theoretical insights into two fluorine-containing imidazoline Schiff base inhibitors for carbon steels in hydrochloric acid solution

Abstract

In this article, two fluorine-containing imidazoline Schiff base derivatives have been synthesized for corrosion inhibition of carbon steels, namely, (E)-N-(3-(1H-imidazol-1-yl)propyl)-1-(4-fluorophenyl)methanimine (FIM1) and (E)-N-(3-(1H-imidazol-1-yl)propyl)-1-(4-(trifluoromethyl)phenyl)methanimine (FIM2). The structures of the two synthesized compounds are confirmed by 1H and 13C NMR. The corrosion inhibition performance of the two corrosion inhibitors is tested by weight loss, electrochemical experiment, surface analysis and theoretical calculation. The weight loss and electrochemical experiments show that both imidazole derivatives inhibitors reduce the metal corrosion rate, while the inhibition efficiency values of FIM1 and FIM2 reach 91.17 % and 93.99% with the concentration of 2 mM. Surface analysis experiments are carried out to analyze the morphology and composition of carbon steel surface immersed in HCl solution without and with corrosion inhibitors. Finally, the results of quantum chemical calculation and molecular dynamics simulation confirm the experimental results theoretically. The fluorine-containing imidazoline Schiff bases corrosion inhibitors exhibit more adsorption sites, which provides a unique insight for designing new kinds of corrosion inhibitors with robust protection efficiency even at high temperatures.