Novel gossypol–indole modification as a green corrosion inhibitor for low–carbon steel in aggressive alkaline–saline solution
By Berdimurodov, Elyor; Kholikov, Abduvali; Akbarov, Khamdam; Guo, Lei; Kaya, Savaş; Katin, Konstantin P.; Verma, Dakeshwar Kumar; Rbaa, Mohamed; Dagdag, Omar; Haldhar, Rajesh
Published in Colloids and Surfaces A: Physicochemical and Engineering Aspects
2022
Abstract
The corrosion of low–carbon steel in aggressive alkaline–saline environments is a very large problem. Protecting low–carbon steel from corrosion in aggressive alkaline–saline solutions using green inhibitors is a very important task in industry. However, there are no studies related to low–carbon steel corrosion in aggressive alkaline–saline environments. Green type corrosion inhibitors are an interesting topic of research. However, currently, the studied type inhibitors are not efficient at low concentrations, and there are no studies on them in aggressive alkaline–saline environments in regard to steel corrosion. In this research work, a novel gossypol–indole modification (GIM) is introduced as a green corrosion inhibitor for low–carbon steel in an aggressive alkaline–saline environment. This inhibitor is a large, highly planar structural molecule that is more water soluble than other inhibitors. Its inhibition behavior is stable at high temperatures, and it contains a large number of electron–rich heteroatoms. All of these properties make it an excellent corrosion inhibitor. The inhibition performance of the novel gossypol–indole modification for low–carbon steel in 1 M NaOH + 1 M NaCl is fully characterized by thermodynamic, gravimetric, electrochemical frequency modulation (EFM), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), density functional theory (DFT), molecular dynamics (MD) simulations, scanning electron microscopy (SEM) and energy dispersive X–ray spectrometry (EDX) methods. The results confirm that the novel gossypol–indole modification is an excellent inhibitor, with a maximum inhibition efficiency of 96.01% at 100 mg/L and 0.112 mM. The adsorption behavior follows the Langmuir isotherm. Electrochemical studies have indicated that this modified is a mixed–type corrosion inhibitor, and the theoretical investigations correlate well with the experimental results.