Performance of two epoxy compounds against corrosion of C38 steel in 1 M HCl: Electrochemical, thermodynamic and theoretical assessment

Abstract

In this work, two epoxy compounds, namely: diglycidyl ether ethylene (DGEE) and diglycidyl ether benzene (DGEB) were evaluated as corrosion inhibitors for C38 steel in 1 M HCl medium. This assessment was performed using electrochemical stationary and transiency, density functional theory (DFT) methods, Monte Carlo, and molecular dynamic simulations. Moreover, the surface of the C38 steel before and after the corrosion test was examined using scanning electron microscopy (SEM). The inhibitory performance of both compounds is enhanced by increasing the concentration of the inhibitors tested, we obtained the most efficiency with an optimal concentration of 5 mM of the inhibitors used. This study permitted to survey the evolution of the inhibitory effect of the two epoxy compounds and show that these inhibitors act as mixed-type inhibitors delaying the rate of anodic and cathodic reactions. Their adsorption isotherms are Langmuir type and primary mechanisms involve physical adsorption. Also, the SEM study confirmed that corrosion inhibition of C38 steel occurs by adsorption of inhibiting molecules on the metal surface, which makes a barrier against corrosion of the latter. The Quantum chemical calculations confirmed the obtained experimental results.