Experimental studies and computational exploration on the 2-amino-5-(2-methoxyphenyl)-1,3,4-thiadiazole as novel corrosion inhibitor for mild steel in acidic environment

Abstract

In the present research, a new 1,3,4-thiadiazole derivative, namely the 2-amino-5-(2-methoxyphenyl)-1,3,4-thiadiazole (5-AMT) was synthesized and investigated as corrosion inhibitor for mild steel (M-steel) in molar hydrochloric acid medium. The experimental studies such as weight loss, potentiodynamic polarization (PDP), Linear polarization resistance (LPR) technique and electrochemical impedance spectroscopy (EIS) were performed in order to evaluate the corrosion protection performance of the tested compound. Based on the experimental outcomes, a protection degree of approximately 98 % was achieved exploiting 5 × 10−4 M of 5-AMT after 1 h of immersion at temperature 303 K. Additionally, PDP study highlighted that the investigated 1,3,4-thiadiazole is of mixed-kind inhibitor. Thermodynamic data from adsorption isotherms and activation energies were determined and discussed. It was shown that the adsorption of 5-AMT molecules fits Langmuir isotherm model. Furthermore, in order to characterize the M-steel surface and to comprehend the adsorption mechanism of 5-AMT, XPS analyses were accomplished. Computational studies by DFT and MD simulation were also conducted to correlate the protection properties and quantum chemical parameters of the investigated inhibitor.