Experimental and computational studies on the corrosion mitigation properties of a newly synthesized imine derivative for carbon steel in HCl medium

Abstract

A new imine derivative, namely 4-amino-2-((2,4 dihydroxybenzylidene)amino)-4 oxobutanoic acid (ADAO), was synthesized, characterized, and evaluated as a corrosion inhibitor for carbon steel (CS) in 1.0 mol/L HCl. Its molecular structure was elucidated by different spectroscopic analysis methods such as UV, FTIR, 1H, and 13C NMR. The corrosion inhibition behavior was investigated by weight loss, electrochemical techniques, surface analysis, and computational approaches (quantum chemical calculations and molecular dynamics (MD) simulations). Obtained outcomes showed that the ADAO displayed excellent effectiveness for CS corrosion inhibition, and its inhibition performance raised with its concentration reaching a maximum inhibition efficiency of 97.24% at 10−4 mol/L. Moreover, the influence of immersion time and temperatures were investigated and discussed. The adsorption behavior of the studied inhibitor followed Langmuir isotherm and revealed the presence of both physical and chemical processes upon interaction with the steel surface. Potentiodynamic polarization (PDP) outcomes demonstrated that ADAO acts as a mixed type inhibitor. EIS results showed that the charge transfer resistance Rct increases and double layer capacitance Cdl decreases in the presence of the synthesized imine, which suggests their adsorption on the steel surface. SEM analysis revealed the formation of a protective film on the carbon steel surface. Quantum chemical calculations indicated that the CN is the privileged site for the adsorption of the ADAO on the iron surface.