Corrosion inhibition of mild steel in hydrochloric acid environment using thiadiazole derivative: Weight loss, thermodynamics, adsorption and computational investigations

Abstract

The corrosion inhibition potency of 1-(2-ethylamino-1,3,4-thiadiazol-5-yl)-3-phenyl-3-oxopropan (ETO) for mild steel in 1.0 M hydrochloric acid was investigated by applying weight loss techniques, and quantum chemical calculations. Conditions that determine the potential for corrosion inhibition, including; concentration, the structure of ETO, and solution temperature, were chosen for the study. The highest inhibitive efficacy of ETO was 98.4%, at the optimum concentration (500 ppm) and room temperature. ETO has superior corrosion inhibitive potency in the HCl environment, owing to the presence of the thiadiazole and benzene rings, in addition to carbonyl and amino groups. Applicable thermodynamical equations were used to calculate the activation energy, enthalpy, and entropy. The adsorption isotherms were applied to determine the Gibbs free energy difference. The experimental findings of the investigation revealed that the activation energy of an inhibited process was higher than for an uninhibited process. Furthermore, the increased inhibition efficiency with improving temperature, and the values of ΔGo, indicated that ETO molecules coated the mild steel surface in both chemical adsorption and physical interactions. The adsorption process on the mild steel surface obeys the Langmuir adsorption isotherm. Both experimental and density functional theory (DFT) findings in the current investigation are in excellent agreement.