Efficient Protection of Mild Steel Corrosion in Hydrochloric Acid Using 3-(5-Amino-1,3,4-thiadiazole-2yl)-2H-chromen-2-one, a Coumarin Derivative Bearing a 1,3,4-thiadiazole Moiety: Gravimetrical Techniques, Computational and Thermodynamic Investigations

In this study, a novel organic molecule, 3-(5-amino-1,3,4-thiadiazole-2yl)- 2H-chromen-2-one (3-ATC), has been investigated for its efficiency in the mild steel corrosion inhibition in 1 M hydrochloric acid solution at various temperatures (303, 313, 323 and 333 K) by gravimetrical analysis. The experimental data showed that 3-ATC is an excellent inhibitor for the corrosion of mild steel in a 1.0 M HCl environment, and the protection performance of 3-ATC is higher than 96 % at 0.0005 M 3-ATC. During adsorption, it was noticed that the 3-ATC exhibits strong inhibitory efficiency, and this phenomenon was discovered to follow the Langmuir adsorption isotherm. Furthermore, the thermodynamic parameters were calculated according to the weight loss findings. The value of free energy of adsorption (ΔGads) was determined, and it was indicated that chemisorption and physisorption mechanisms are responsible for the adsorption of 3-ATC molecules on mild steel surfaces. In addition, the quantum chemical DFT research was used to study the relationship between the results of inhibitory efficiency and molecule structure.