Insights into Using a Schiff Base as a Corrosion Inhibitor for Carbon Steel in HCl Medium: Experimental and Theoretical Approaches

Abstract

In an aqueous environment, the corrosion of metals or alloys is often inhibited by the application of organic inhibitors. On carbon steel (CS), N, N′-bis (salicylidene) butylene-1,4-diamine (SB) was investigated for its anticorrosive properties. With the use of potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and weight loss (WL) measurements, corrosion behavior in the temperature range of 298-333 K, both with and without the SB inhibitor, was predicted. A maximal inhibitory effectiveness of 84.0% was observed in half molar HCl at 298 K, and it rises as SB (50-300 ppm) concentration increases. The variation in kinetic and thermodynamic properties of SB on CS indicates mixed adsorption (physisorption and chemisorption). The polarization curves indicate its mixed kind of inhibition activity followed by the Langmuir adsorption isotherm. The experimental results are supported by density functional theory (DFT) and Monte Carlo (MC) simulations, indicating the potential corrosion inhibition behavior of SB on CS in acidic environments. SEM and EDX analyses revealed the development and adsorption of a continuous layer at CS in the presence of the SB chemical. The quantum characteristics of SB supported its efficacy as an inhibitor.