Mechanistic insights into mild steel corrosion inhibition in alkaline media using synthesized ionic liquid

This study evaluates the corrosion inhibition potential of synthesized ionic liquids for mild steel in 1M NaOH solution. The inhibitors, prepared using dimethylamine, isopropyl chloride, and imidazole, were analyzed through thermometric, gravimetric, and electrochemical methods. Results showed that the inhibitors effectively reduced corrosion rates and a maximum inhibition efficiency of 88.9 % was achieved at an optimum inhibitor concentration of 0.7 g/L. Thermometric analysis revealed a significant reduction in reaction numbers, while gravimetric measurements indicated a weight loss reduction of up to 85 % compared to the uninhibited system. Electrochemical studies demonstrated enhanced corrosion resistance, with a substantial increase in charge transfer resistance (Rct) from 41.2 Ω cm² (blank) to 257.5 Ω cm² (0.7 g/L inhibitor). Adsorption isotherm analysis indicated adherence to Langmuir behaviour, with an adsorption equilibrium constant (k) of 0.904 and a coefficient of determination (R²) of 0.9953, thus suggesting monolayer adsorption. Scanning Electron Microscopy (SEM) revealed smoother surface morphology in the presence of the inhibitors, while Density Functional Theory (DFT) calculations showed favourable adsorption energy (-44.13 kJ/mol) and a low energy gap (ΔE = 4.63 eV), highlighting the inhibitors’ reactivity. These findings confirm the effectiveness of ionic liquids as eco-friendly inhibitors for mild steel corrosion in alkaline environments and underscore their potential for industrial applications requiring sustainable corrosion protection strategies.