Corrosion inhibition studies of new synthesized 1,4-dioctyl-6-methyl-1,4-dihydroquinoxaline-2,3-dione on mild steel in 1.0 M HCl solution using gravimetric and electrochemical techniques supported by theoretical DFT calculations

Abstract

The inhibition performance of 1,4-dioctyl-6-methyl-1,4-dihydroquinoxaline-2,3-dione (AY15) was studied as an inhibitor of mild steel in 1.0 M HCl solution at 308 K using experimental methods and theoretical calculations. 1,4-dioctyl-6-methyl-1,4-dihydroquinoxaline-2,3-dione (AY15) was synthesized and identified by elemental analysis, IR,1H NMR and13C NMR spectroscopy. The corrosion inhibition of (AY15) in 1.0 M HCl solution for mild steel was evaluated using weight loss and electrochemical techniques. The weight loss results show that inhibition efficiency increasing with increasing AY15 concentration and maximum value was obtained at 10–3 M concentration. Polarization analysis suggests that compound act as a mixed type of inhibitor. EIS data showed that in the presence of inhibitor, transfer resistance increased and Cdl decreased due adsorption of inhibitor at the metal surface. It was found also that the adsorption of the inhibitor on the mild steel surface obeys the Langmuir isotherm model. The weight loss, electrochemical and Density Functional Theory (DFT) calculations are in good agreement.