Preparation of Schiff base derivates from leucine and its inhibition effect on the atmospheric corrosion of mild steel

Background Schiff bases are attractive as eco-friendly corrosion inhibitors for the protection of metals. In this study, a novel volatile corrosion inhibitor (VCI) based on Schiff base (LEU-T) is synthesized from leucine and salicylaldehyde. This study evaluates the volatile corrosion inhibition performance of LEU-T on mild steel and examines its anti-corrosion effect in a simulated atmospheric corrosion solution. Methods The corrosion inhibitor is characterized by Fourier transform infrared (FT-IR) absorption spectra. The corrosion behavior, inhibition efficiency, and anti-corrosion mechanism of the inhibitor on mild steel are evaluated using volatile inhibition ability (VIA) tests, electrochemical measurements (including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)), and theoretical calculations. Scanning electron microscopy (SEM) and atomic force microscope (AFM) confirm the formation of the inhibitive films on mild steel. Significant Findings The results demonstrate that LEU-T exhibits outstanding inhibition efficiency of 82.18 % in VIA tests. Electrochemical measurements indicate that the formed inhibitive films on the steel substrate lead to an increase in the charge transfer resistance. The corrosion inhibition efficiencies of leucine and LEU-T, as determined by electrochemical impedance spectroscopy, are 67.84 % and 83.90 %, respectively. SEM and AFM observations indicate that the inhibitor forms a protective VCI coating, effectively retarding the steel corrosion. The LEU-T has larger adsorption energy (-136.13 kJ/mol) compared to leucine (-88.48 kJ/mol) on mild steel.