Evaluation of structure-reactivity correlation of efficient corrosion inhibitor ionic liquids for mild steel in acidic medium

Abstract

The synthesis and characterization of Imidazolium cation-based ionic liquids having different anions were reported in the present article. The physicochemical and spectral analyses were used to characterized these ionic liquids. The theoretical studies using the B₃LYP method provide optimized structure, HOMO–LUMO plots, thermodynamic parameters, and quantum descriptors. The anti-corrosive property of Imidazolium cation-based ionic liquids was observed in 0.5 M H₂SO₄ corrosive medium at 303, 313, 323, and 333 K temperatures by various strategies like gravimetric studies, electrochemical impedance spectroscopy, potentiodynamic polarization studies, and scanning electron microscopy (SEM). The interesting feature of this article is that both ionic liquids follow different adsorption isotherms. IL-1 ionic liquid shows physisorption adsorption behavior, and IL-2 exhibits mixed adsorption (chemisorptions and physiorption). The electrochemical strategies and E_gap value obtained from DFT reveal the maximum inhibition efficiency of IL-2 for the corrosion process in an acidic medium on mild steel. Potentiodynamic polarization studies reveal the mixed type behavior for ionic liquid inhibitors. EIS results indicate that the inhibition efficiency improved by enhancing ionic liquids concentration. The protective layer formation or adsorption of ionic liquid on metallic surface was confirmed by SEM. In the present article, the proposed mechanism shows the blockage of anodic and cathodic sites by ionic liquids to inhibit the corrosion process on mild steel in an acidic medium.

Graphical abstract

Keywords:

• Ionic liquids
• gravimetric method
• quantum descriptors
• electrochemical study
• adsorption isotherm

Acknowledgments

The authors are highly grateful to the Head of the Department of Pure and Applied Chemistry, University of Kota, Kota, for providing facilities for the department. The authors also thank MRC and MNIT Jaipur for providing spectroscopic facilities and DFT support.

Disclosure statement

The authors declare no conflict of interest, financial or otherwise.

Data availability statement

The datasets generated during and analyzed during the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

This research article has not received any grant from the funding agency.

Notes on contributors

Ashish Rathore

Ashish Rathore: All experimental work and data analysis. Shobhana Sharma: Interpretation of data, drafting the article, conception or design of work. Ankit Sharma: Done required critical revision. Sushil Kumar Sharma: Provide guidance and final approval of the version to be published.