Investigation of Corrosion Inhibition of Carbon steel in Acid Chloride Environments by Vinyl Imidazole Using a Combined Electrochemical and Computational Evaluation
摘要
This work examines the corrosion inhibition properties of vinyl imidazole on carbon steel in 1 M HCl. The study employed hydrogen evolution measurements across 303–333 K, alongside electrochemical techniques and computational analyses (DFT) to clarify the inhibition mechanism. Findings show that inhibition efficiency increased with concentration, reaching a maximum of 96.3% at 0.4 g L−1 and 303 K, with a slight decline to 95.7% at 0.8 g L−1, suggesting minor structural reorganization at higher concentrations. Electrochemical data revealed that charge transfer resistance (Rct) increased to 33,051 Ω·cm2, while corrosion current density (icorr) decreased significantly at optimal concentration, reflecting a protective layer. Adsorption obeyed the Langmuir isotherm, with Kads decreasing from 0.6535 to 0.1953 mg L−1 and ΔGads ranging from –7.7 to –1.4 kJ mol−1 over the temperature range, confirming spontaneous, primarily physisorptive adsorption. Thermodynamic parameters showed increases in activation energy (Ea = 53.87 to 117.31 kJ/mol), enthalpy (ΔH = 79.37 to 59.58 kJ/mol), and entropy (ΔS = 10.58 to 99.98 J/mol·K) with increasing concentration, indicating enhanced energy barriers and interfacial disorder. Computational evaluations revealed a HOMO–LUMO gap of 5.545 eV, elevated HOMO energy (6.739 eV), and prominent π* and LP → π* interactions, corroborating adsorption and film stability. Overall, vinyl imidazole exhibits high concentration- and temperature-dependent inhibition efficiency through physisorptive adsorption, offering substantial protection to carbon steel in acidic conditions.