Optimization of the corrosion inhibition performance of novel oxadiazole thione-based Schiff base for mild steel in HCl media using Doehlert experimental design

This study aimed to evaluate the effectiveness of 3-((dicyclohexylamino) methyl)-5-(4-((3, 4-dimethoxybenzylidene) amino) phenyl)-1, 3, 4-oxadiazole-2(3H)-thione (DMOT) in inhibiting the deterioration of mild steel in a 1 M HCl solution. Weight loss and electrochemical measurements were used to assess the inhibition performance and synthesis of DMOT. The characterization of DMOT was conducted through NMR and FTIR measurements, while SEM and AFM were used in the surface analysis. DFT calculations were used to investigate the chemical and theoretical properties of DMOT. The results of electrochemical measurements showed that the inhibition efficiency increased as the concentration of the inhibitor increased, with an optimal concentration reaching an inhibition efficiency of 99.17%. Polarization curves revealed that DMOT molecules behaved as a mixed-type inhibitor, with adsorption following the isotherm of Langmuir. The adsorption of DMOT on the corroded metal's surface was verified by SEM and AFM investigations. Using quantum chemical calculations, the quantum chemical properties of the DMOT were evaluated.