An eco-friendly corrosion inhibitor Cuscuta reflexa extract and PEG400 for mild steel inhibition in acidic medium: computational and experimental investigations

Herein, the mechanism of corrosion prevention of mild steel (MS) by extract of Cuscuta reflexa/Amarbel (AME) as green inhibitor is explained by gravitational, electrochemical measurements. The viability of neat extract and after adding an intensifier was investigated as corrosion inhibitor for MS in hydrochloric acid. The presence of electron-rich moieties in AME was characterized through Fourier-transform infrared spectroscopy (FTIR). Furthermore, polarization measurements showed that AME acted as a mixed type inhibitor against corrosion. The formulation of 100 ppm AME with 50 ppm polyethylene glycol 400 (PEG400) as an intensifier showed inhibition efficiency of 97.51% for MS in 0.5 M HCl. The protection of MS in (AME + PEG) formulation was also assessed through the Langmuir, Freundlich, and Flory-Huggins adsorption isotherm model. The surface studies of the MS were examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM) that indicated a smoothened surface of the metal in the presence of the studied compounds. XPS study was executed to analyze the interaction of the inhibitor with the metal surface. In addition, computational quantum study provides the molecular structural relationship with corrosion inhibitive competence of the extract.

Automated summary

This study explains the mechanism of corrosion prevention of mild steel using extract of Cuscuta reflexa/Amarbel as a green inhibitor through gravitational and electrochemical measurements. The results show that the addition of polyethylene glycol 400 as an intensifier enhances the corrosion inhibition efficiency of the extract in hydrochloric acid, providing a protective effect for the mild steel.