Experimental, DFT studies and molecular dynamic simulation on the corrosion inhibition of carbon steel in 1 M HCl by two newly synthesized 8-hydroxyquinoline derivatives

Abstract

In the present work, two new 8-hydroxyquinoline derivatives namely, 5-(((2-hydroxybenzylidene)amino)methyl) 8-hydroxyquinoline [HBMQ] and 5-(((4-chlorobenzylidene)amino)methyl) 8-hydroxyquinoline [CBMQ] were synthesized and investigated as corrosion inhibitors against the dissolution of carbon steel (C38 steel) in 1 M HCl. These compounds were obtained with high yield, and their structures were characterized by nuclear magnetic resonance spectroscopy (NMR) and elemental analysis. Gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and surface morphology analyses utilizing scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) were used to quantify inhibitory performance. The adsorption process of inhibitory compounds was then demonstrated using quantum mechanics approaches such as Density Functional Theory (DFT) and Molecular Dynamic Simulation (MD). Based on EIS results, the investigated derivatives effectively inhibit the degradation of C38 steel over the entire concentration range with a maximum efficiency of 91.9% and 88.0% for [CBMQ] and [HBMQ], respectively, at 10−3 M. In addition, the PDP studies revealed that [HBMQ] and [CBMQ] compounds acted according to a mixed-type mechanism. Moreover, the adsorption mechanism follows the Langmuir isotherm model. The quantum theoretical study by DFT and MD simulation confirmed the experimental results.