Electrochemical, thermodynamic and molecular dynamics studies of some benzoic acid derivatives on the corrosion inhibition of 316 stainless steel in HCl solutions

Abstract Some benzoic acid derivatives such as benzoic acid (C1), para-hydroxybenzoicacid (C2), and 3,4-dihydroxybenzoic acid (C3) were investigated as corrosion inhibitors for AISI 316 austenitic stainless steel (SS) in aggressive 0.5 M HCl solution using weight loss (WL) measurements, electrochemical measurements, and scanning electron microscopy (SEM) analysis, radial distribution function (RDF), molecular dynamics (MD). The aim of this work is to determine the inhibition efficiency based on the concentration of studied inhibitors and the temperature effect of medium. The maximum inhibition efficiency (≈ 88%) was obtained in the presence of the optimum inhibitor concentration of 1.0 × 10−2 M for C3 at 291 K. The experimental data showed that the inhibition efficiency of these inhibitors increases with the increase of their concentrations. The temperature effect on the corrosion inhibition of (SS) in 0.5 M HCl with and without inhibitors at different concentrations was investigated from 291 K to 318 K temperature range. It should be noted that each test has been carried out at least three times. Besides, the result was calculated by averaging the obtained values of each test. The activation energy and thermodynamic parameters evaluated from the weight loss measurements, suggested that the adsorption is spontaneous, exothermic, and obeyed the Villamil adsorption isotherm. SEM analyses confirmed that C3 is a good inhibitor compared with C1 and C2. Molecular dynamics simulations diagnosis for molecule/metal interaction showed that the studied organic compounds have strong interactions with Fe (110) and therefore good inhibition power for AISI 316 austenitic stainless steel (SS) against corrosion.