Unravelling the adsorption and anti-corrosion potency of newly synthesized thiazole Schiff bases on C-steel in 1 M HCl: Computational and experimental implementations
Ahmed A. Farag, Arafat Toghan
Abstract
• Methyl-thiazolone-Schiff bases derivatives were synthesized. • In 1 M HCl environment, Methyl-thiazolone derivatives were inspected as inhibitors for C-steel corrosion. • PDP studies revealed that Methyl-thiazolone derivatives functioned as mixed inhibitors. • Adsorption data discovered that the inhibitor followed the Langmuir model. • There is a strong correlation between the theoretical and the experimental approaches. However, steel has many unique properties and advantages that have made it an essential component in industry, construction, and many other engineering fields, but it is greatly affected by the surrounding environment, which leads to its damage. From this point, two brand-new synthezied eco-friendly Schiff base based thiazoles, specifically 2-[(E)-1-(2-Pyridyl)propylideneamino]-5-methyl-5H-1,3-thiazol-4-one ( SCH-1 ) and 2-(Z)-[3-(Methoxymethyl)-1-methyl-1H-pyrazol-4-yl]methylideneamino-5-methyl-5H-1,3-thiazol-4-one ( SCH-2 ) were explored as inhibitors for carbon steel (C-steel) corrosion in 1 M HCl. The anticorrosion capability was practically estimated by electrochemical and chemical measurements. At 303 K, the SCH-1 and SCH-2 compounds exhibit peak inhibition rates of 92.3 % and 93.7 %, respectively. Thermodynamic studies confirmed that the corrosion inhibition resulted from the adsorption of SCH-1 and SCH-2 molecules on the steel surface obeying Langmuir adsorption isotherms with a physicochemical adsorption nature. Studies of thermodynamics verified that the suppression of corrosion was due to the adsorption of SCH-1 and SCH-2 molecules on the steel surface, which followed physicochemical adsorption isotherms according to Langmuir adsorption isotherms. Potentiodynamic polarization (PDP) confirmed that SCH-1 and SCH-2 are mixed-type inhibitors. To better understand the inhibition and adsorption behavior of SCH-1 and SCH-2 molecules on the Fe(110) surface, various computational models have been applied including Mulliken population analysis, molecular electrostatic potential surface (ESP), density functional theory (DFT), natural bond orbital analysis (NBO), and molecular dynamics simulation (MDS). The theoretical finding showed that the interaction/binding energies of SCH-2 molecules are much higher than that of SCH-1 molecules. This conclusively confirms the strong adsorption of SCH-2 molecules on the metal-surface, which in turn highlights its superior inhibitory capacity. Theoretical and practical studies are fully compatible, and the inhibition mechanism was suggested.