Experimental and molecular modeling approach on the corrosion behavior of mild steel in HCl solution with quinoxaline inhibitors

Abstract

Two new quinoxaline derivatives namely (E)-3-(2-chlorostyryl)quinoxalin-2(1H)-one (CSQO) & (E)-3-(2-(thiophen-2-yl)vinyl)quinoxaline-2(1H)one (TVQO) were synthesized and identified through the following methods like infrared (IR) analysis, mass spectrometry,¹H NMR and ¹³C NMR. Weight loss, electrochemical techniques [PDP&SIE], surface analytical techniques [SEM&UV-Visible], quantum chemical calculations [DFT], and MD simulations have all been used to examine the effectiveness of CSQO and TVQO in preventing the corrosion of mild steel. According to the findings of the experiments, the inhibitors CSQO and TVQO effectively suppress the corrosion of mild steel in 1 M HCl solution, with maximum corrosion inhibition of 97.0 and 95.5% at 10⁻³ M for CSQO and TVQO, respectively. Based on PDP investigations, CSQO and TVQO function as mixed-type inhibitors, and their adsorption on the MS surface follows the Langmuir adsorption isotherm and the mode of adsorption is chemisorption. Both surface investigations (SEM and UV-Visible) have validated the protective layer that developed on the metal surface. DFT calculations and MD simulations were used to study the association between inhibitor molecular structure [CSQO and TVQO] and inhibitory efficacy, and they closely match the experimental findings.