Lignin-Derivative Ionic Liquids as Corrosion Inhibitors

Area of Science:

• Materials Science
• Electrochemistry
• Green Chemistry

Background:

• Corrosion of structures causes significant economic loss and safety hazards.
• Bio-based corrosion inhibitors, particularly lignin derivatives and ionic liquids (ILs), offer eco-friendly and tunable alternatives.
• Combining lignin and ILs can yield novel compounds with enhanced corrosion inhibition properties.

Purpose of the Study:

• To investigate the corrosion inhibition properties of novel bio-based lignin ionic liquids (ILs) for mild steel.
• To evaluate the influence of anion and cation variations on corrosion inhibition in a 0.01 M NaCl solution.
• To characterize the protective surface layer formed by the inhibitors.

Main Methods:

• Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) and Cyclic Potentiodynamic Polarization (CPP) were employed to assess electrochemical behavior.
• Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and optical profilometry were used for surface characterization.
• Corrosion current density was measured for mild steel in a sodium chloride solution with and without the synthesized ILs.

Main Results:

• The lignin-based IL choline syringate demonstrated significant corrosion inhibition, reducing the corrosion current density from 1.66 µA/cm² to 0.066 µA/cm² after 24 hours in 0.01 M NaCl.
• The study identified specific anion and cation effects on the performance of the lignin ILs.
• Surface analysis confirmed the formation of a protective layer on the mild steel.

Conclusions:

• Bio-based lignin ILs, especially choline syringate, are effective and environmentally friendly corrosion inhibitors for mild steel in saline conditions.
• The developed ILs possess desirable properties such as availability and good biological/environmental tolerance.
• This research presents a promising pathway for sustainable corrosion prevention strategies using renewable resources.