Novel glycoluril pharmaceutically active compound as a green corrosion inhibitor for the oil and gas industry

Abstract

• GCU is introduced as a green corrosion inhibitor. • Maximum inhibition efficiency of GCU is 95.62% at 100 mg/L/0.08 mM. • GCU is a mixed-type corrosion inhibitor. • Bond length of Fe-O is approximately 2.4 Å. • Adsorption energy of GCU on Fe(1 0 1) surface is − 390.1 kcal/mol. The corrosion of St3 steel in 1 M NaCl saturated with CO 2 and H 2 S is a large problem in the chemical industry; therefore, creating green and more efficient inhibitors is an urgent task. However, there have been extremely limited research results related to this problem. In this research, a novel glycoluril pharmaceutically active compound (GCU) was first introduced as a green corrosion inhibitor for St3 steel in 1 M NaCl saturated with CO 2 and H 2 S. The inhibition properties of the novel glycoluril pharmaceutically active compound were fully characterized by thermodynamic, gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), electrochemical frequency modulation (EFM), linear polarization resistance (LPR), density functional theory (DFT), molecular dynamics (MD) simulation, scanning electron microscopy (SEM) and energy dispersive X–ray spectrometry (EDX) methods. The obtained results indicated that this inhibitor is an excellent inhibitory molecule, and its maximum protection degree was 95.62% at 100 mg/L/0.08 mM. The adsorption behaviour of this inhibitor was characterized from a Langmuir isotherm. Electrochemical studies demonstrated that this molecule is a mixed–type corrosion inhibitor. The theoretical calculations indicated a good correlation with the experimental results and confirmed that the adsorption–inhibition character depends on the molecular structure of the inhibitor and that the protonated form of the inhibitor is more inhibited than its neutral form.