A new synthesized coumarin-derived schiff base as a corrosion inhibitor of mild steel surface in hcl medium: Gravimetric and dft studies

Abstract

The inhibition efficiency of a new coumarin derivative, namely 2-(6-methylcoumarin-4-yl)-N´-(3-nitrobenzylidene)acetohydrazide (MCNAH), in controlling corrosion of mild steel in 1 M hydrochloric acid solution was investigated by gravimetric techniques at various temperatures (303, 313, 323 and 333 K). The impact of immersion time and temperature on inhibition performance of MCNAH was also studied. MCNAH was synthesized and the chemical structure was elucidated by magnetic resonance spectroscopy (MRS) and Fourier-transform infrared spectroscopy (FT-IR). The experimental results suggested that MCNAH is an excellent corrosion inhibitor for mild steel in 1 M hydrochloric acid environment. The synthesized inhibitor (MCNAH) has the ability to impede the corrosion of mild steel in 1 M hydrochloric acid environment at low and high concentrations. The inhibitive efficiency was found to increase with increasing concentration of MCNAH and decrease with increasing time and temperature. The thermodynamic parameters were estimated and discussed. The adsorption of the synthesized inhibitor on the surface of the tested mild steel in the presence of HCl obeyed the Langmuir adsorption isotherm. The relationship between the structure of the new synthesized inhibitor and its inhibitive effects was investigated using theoretical calculations. The experimental and density functional theory (DFT) calculation results are in good agreement. The results clearly show that the inhibition mechanism involves a blocking mechanism of action of the inhibitor.