Contribution to the corrosion inhibition of carbon steel by 5-(2-ethoxybenzylidene) 1,3-dimethylbarbituric acid in HCl solution: Experimental and theoretical study

The inhibiting impact of ecofriendly 5-(2-ethoxybenzylidene) 1,3-dimethylbarbituric acid (5-EBMB) in 1 M HCl on the corrosion of C-steel has been examined via weight loss (WL) method, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) techniques”. The obtained results demonstrate that the studied chemical is good 5-EBMB and that, in both PDP and EIS methods, its inhibition efficiency (%IE) increases with increasing concentration, reaching 82.5 at 21x10^-6 M. Conversely, when the temperature rose, the percentage of IE reduced. “The adsorption of the investigated derivative on the surface of C-steel follows Langmuir isotherm. The adsorption process of the investigated compound is spontaneous and considered as chemisorption type”. PDP curves revealed that the studied derivative is mixed-type inhibitor. Furthermore, the EIS results verified that the compound under investigation had adsorbed on the C-steel surface by raising the charge transfer resistance (Rct) to 139.7 ohm cm² and decreasing the double layer (Cdl) capacitance from 102 to 69 µF cm^-2. The inhibitor adsorption on the C-steel surface was confirmed by surface examination using atomic force microscopy (AFM), energy dispersive X-ray (EDX), and scanning electron microscopy (SEM). Additionally, quantum chemistry and molecular dynamic simulation were used to extensively examine the mechanism of 5-EBMB's corrosion inhibition. All tested methods gave good agreement.