Hydrazone-based green corrosion inhibitors for API grade carbon steel in HCl: Insights from electrochemical, XPS, and computational studies

Abstract

Corrosion protection of carbon steel (CS) is an important challenge in the industry field. The search for an effective protection approach is still a hot research question. In the present work, three hydrazone derivatives (HZ-OH, HZ-Me, and HZ-Cl) were used in 1.0 M HCl solution for API grade CS corrosion mitigation. Their corrosion inhibition performance was evaluated by electrochemical tests while steel surface was analyzed by Xray photoelectron spectroscopy (XPS), contact angle and scanning electron microscope (SEM). Electrochemical tests showed an inhibition efficiency between 91% and 98% for CS exposed to acidic solution containing 0.05 mol/L of the three hydrazone derivatives. All compounds were classified as mixed type inhibitors, inhibiting both cathodic and anodic corrosion reactions. XPS showed that inhibitor molecules formed a stable layer on steel surface through chemical and physical interactions. The adsorption of molecules onto the steel surface was found to follow Langmuir model. DFT and MD simulations were used to investigate the interaction of hydrazones with Fen (n = 1-4) and Fe2O3(001) surface, respectively. They confirmed that the inhibitor with two hydroxy groups (HZ-OH) had a greater interaction with iron atoms.