Bio-based ionic liquid as a corrosion inhibitor for mild steel in 5% HCl solution: Experimental and theoretical investigation

In pickling conditions, corrosion inhibitors are commonly used to mitigate the corrosive effects of the acidic environment on metal surfaces. Green corrosion inhibitors are substances that provide corrosion protection while being environmentally friendly, often derived from renewable resources or having minimal environmental impact. Ionic liquids are a class of green corrosion inhibitors that have gained attention for their potential in corrosion protection due to their unique properties. In this study, we synthesized a bio-based choline hexanoate ionic liquid (referred to as ChH) and used FT-IR and 1H NMR spectroscopy to elucidate its structure. Further the effectiveness of ChH IL was examined in preventing MS corrosion in 5% HCl at 20–80 °C. The corrosion behavior of MS was examined using weight loss, potentiodynamic polarization, and EIS measurements. Increasing inhibitor concentration and temperatures improved the inhibition performance. The highest efficiency i.e., 98.16% was observed at 3.3 × 10−3 M of ChH at 60 °C. To verify the adsorption of ChH on the MS further investigations were done using FT-IR, Raman, and XPS analysis.