Adsorption and Corrosion Inhibition Mechanism of Schiff Base Conjugated Oligoelectrolyte on Mild Steel in Acidic Media: Electrochemical and Surface Characterization Studies

Abstract

The potential of conjugated oligoelectrolyte (COE) derivatives to mitigate corrosion of mild steel remains unexplored. So, the present study demonstrates a detailed description of the preparation and characterization of a Schiff base conjugated oligoelectrolyte (BTC-SBCOE), followed by its investigation as a corrosion inhibitor. The Schiff base (SB) synthesized from benzene-1,3,5-tricarbaldehyde with 4-aminophenol is functionalised with an ionic polar pendant at the terminal oxyl position to afford BTC-SBCOE and is characterized by FTIR, 1H-NMR, 13C-NMR spectroscopy, and mass spectrometry. In acidic media, quaternary ammonium bromide groups improve the stability and effectiveness of the BTC-SBCOE by creating a steric-electrostatic barrier. The gravimetric technique, electrochemical impedance spectroscopy, and potentiodynamic polarization, are utilized to assess the anticorrosion effectiveness of BTC-SBCOE towards the dissolution of mild steel in 2M HCl (7.2%) at different concentrations and in the temperature range 25-80˚C. The gravimetric investigations suggest an inhibition efficiency of 90.38% at 5 mM. The surface examination employing scanning electron microscopy and atomic force microscopy validated the creation of a protective layer on the surface. The thermodynamic results designate that the binding of BTC-SBCOE is governed by physical and chemical adsorption on the mild steel surface, which prevents corrosion. The overall finding indicates that BTC-SBCOE is a long-lasting and efficient corrosion inhibitor for mild steel in acidic media.