Experimental and theoretical study of Sodium Cocoyl Glycinate as corrosion inhibitor for mild steel in hydrochloric acid medium

Abstract

Corrosion of metals is a big economic concern all over the globe. Corrosion inhibitors, particularly those based on surfactants, are one of the utmost efficient methods of defense of metal surfaces against corrosion. This research looks at the application of the amino acid-based surfactant Sodium Cocoyl Glycinate (SCG) as a corrosion inhibitor. The inhibitor's ability to protect a mild steel (MS) sample in 1 M HCl was investigated, and it was shown to be quite effective. The inhibitory behaviour of SCG on MS corrosion was investigated employing procedures such as weight loss (WL), Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization (PDP), Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM) and so on. Based on the temperature and concentration of inhibitor, the compound resisted MS corrosion to varying degrees. At 30 °C, SCG showed a 95.21 % inhibition efficiency (IE%) at 0.2864 mM which reduced to 73.21 % at 60 °C. Thermodynamic and kinetic parameters of MS corrosion and inhibitor adsorption were evaluated and addressed. The Gibbs free energy of adsorption (ΔGads0) was calculated to be in between −30 and −40 KJ mol−1, depicting mixed adsorption (i.e., both chemisorption and physisorption). Quantum chemical parameters were employed to investigate surfactant reactivity and adsorption behaviour. The outcomes of the experimental investigation and the theoretical study were well-aligned.