Investigation of Anticorrosive Property of Carbazolecarbaldehyde Azine on Mild Steel Using Electrochemical, Morphological and Theoretical Studies

Abstract: Mild steel (MS) is one among the extensively utilized materials in several industrial sectors, but prone to deterioration when exposed to acidic environment. The main focus of this study is to examine the corrosion inhibitive efficacy of 9-ethyl-3-carbazolecarboxaldehyde azine (CCA) on MS immersed in 0.5 M HCl medium. The corrosion inhibition efficiency of CCA which was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques improved with rise in temperature and inhibitor concentration. CCA showed a maximum inhibition efficiency of 92.4% at 323 K for 5 × 10^–5 M concentration in 0.5 M HCl medium. The variation in the kinetic and thermodynamic parameters indicated chemisorption of CCA on MS, and its mixed-type inhibitive action followed Langmuir’s isotherm model. The infrared spectra provided evidences for the chemical interaction of CCA with MS specimen. Surface morphology evaluation using SEM and AFM in combination with elemental analysis using an energy dispersive X-ray analyser (EDX) indicated the creation of a protective adsorption layer of CCA on MS surface. The quantum chemical investigations performed using density functional theory (DFT) computations supplemented the experimental results, suggesting the potential corrosion inhibition behavior of CCA toward MS in aggressive HCl medium. Graphic Abstract: [Figure not available: see fulltext.].