An electrochemical and theoretical approach towards the efficient microwave synthesis of imidazolium-based ionic liquids for unprecedented mild steel corrosion inhibition in 0.5 M H2SO4 solution

• Published in: Results in surfaces and interfaces 2024-10, Vol.17, p.100295, Article 100295
• Main Authors: Sharma, Shobhana, Rathore, Ashish, Thakur, Abhinay, Gurjar, Shriniwas, Sharma, Ankit, Kumar, Ashish, Sharma, Sushil Kumar
• Format: Article
• Language: English
• Subjects: Corrosion; DFT; H2SO4 solution; Inhibition; Ionic liquids; Mild steel
• ISSN: 2666-8459; 2666-8459
• DOI: 10.1016/j.rsurfi.2024.100295

The inhibition potential of newly synthesized imidazolium-based ionic liquids (IL-1 and IL-2) on mild steel corrosion in a 0.5 M H2SO4 solution has been comprehensively investigated using gravimetric analysis, potentiodynamic polarization, and electrochemical impedance spectroscopy across various temperatures. Gravimetric analysis indicated that the adsorption of these inhibitors adhered to the Langmuir adsorption isotherm. Significantly, IL-2, featuring a longer alkyl chain, demonstrated superior inhibition efficiency (92.51 % at 303 K) compared to IL-1 (88.71 % at 303 K). Potentiodynamic polarization studies revealed a mixed-type inhibitory behavior, impacting both anodic and cathodic reactions. Surface morphological analyses via SEM and EDX confirmed the formation of a protective film on the mild steel surfaces, substantiating the corrosion inhibition capabilities of IL-1 and IL-2. The novelty of this research lies in the application of density functional theory (DFT) using the B3LYP method, which elucidated that the alkyl chain length at the N-3 position in imidazolium cation-based ionic liquids significantly enhances their inhibition potential. This mechanistic insight suggests that these ionic liquids effectively obstruct both anodic and cathodic sites, providing robust corrosion protection in a 0.5 M H2SO4 solution. [Display omitted] •IL-2 showed 92.51% inhibition efficiency at 1000 ppm in 0.5 M H2SO4 solution.•EIS confirmed a protective layer, increasing charge transfer resistance with inhibitors.•Potentiodynamic tests revealed Icorr reduced to 92.29 μA/cm2 for IL-2 at 1000 ppm.•Quantum analysis indicated strong adsorption and high molecular polarity for IL-2.•SEM confirmed better surface protection with higher concentrations of inhibitors.