Electrochemical and Quantum Chemical Calculations of Two Schiff Bases as Inhibitor for Mild Steel Corrosion in Hydrochloric Acid Solution

Abstract

The corrosion inhibition characteristics of two synthesized Schiff bases, namely N, N´-bis(2-hydroxy-6-nitrobenzaldehyde) benzidine and N, N´-bis(salysylaldehyde) benzidine, on the mild steel corrosion in 2.0 M hydrochloric acid have been investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. These studies were carried out at different concentrations, temperatures and durations. Polarization measurements indicate that the two inhibitors act as mixed type inhibitors. The adsorption of inhibitors obeys the Langmuir adsorption isotherm and the thermodynamic parameters (E_a, K_ads, ΔG⁰_ads) were calculated and discussed. Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies determined experimentally.