Exploring the mechanisms of eco-friendly pyridinium ionic liquids for corrosion inhibition of carbon steel in saline mediums: Unveiling deeper understanding through experimental and computational approaches

Abstract

Addressing the ongoing issue of carbon steel corrosion, this study evaluates the corrosion inhibition performance of two eco-friendly pyridinium-based ionic liquids, 4-(dimethylamino)-1-nonylpyridin-1-ium Bromide (4DMN) and 4-(dimethylamino)-1-(prop-2-yn-1-yl)pyridin-1-ium Iodide (4DMP), in a 3.5 wt% NaCl solution. Weight loss tests, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), quantum chemical calculations (QCCs), and molecular dynamics (MD) simulations were employed to carried out experimental and theoretical studies. Both 4DMN and 4DMP showed concentration-dependent inhibitory effects with 94 % and 92 % effectiveness, respectively. Potentiodynamic data showed that these compounds control both anodic and cathodic reactions without changing the corrosion mechanism. EIS results indicated a decrease in double-layer capacitance, suggesting adsorption of IL molecules on steel surface. Over a 60-h period, 4DMN maintained its effectiveness, although it decreased at higher temperatures. Surface analyses using Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM) showed improvements in surface morphology and roughness. Computational studies supported these findings, showing the reactivity and adsorption patterns of the ILs on the Fe (110) surface. Overall, this study contributes to understanding how pyridinium-based ILs can be used for effective and sustainable corrosion control.

Keywords

• Corrosion inhibition
• Carbon steel
• Ionic liquids
• Electrochemical techniques
• Density functional theory
• Molecular dynamics