Experimental and theoretical studies of the effect of Ballota hirsuta essential oil on carbon steel corrosion in a molar concentration of HCl

Abstract

• The inhibition of CS in 1 m HCl by EOBH is studied. • EOBH average inhibition efficiency (IE) is around 95.00 % at 2.00 g/L. • SEM-EDX analysis showed that the CS surface is covered EOBH. • Adsorption of typical organic compounds of EOBH on CS surface is studied theoretically. In this research, natural essential oil extracted from Ballota hirsuta (EOBH) was explored as a sustainable and effective corrosion inhibitor for carbon steel (CS) during acid cleaning. EOBH's efficacy as a green inhibitor was assessed in a 1.00 M HCl solution using electrochemical methods such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The results demonstrated that EOBH exhibits significant anticorrosion properties, achieving an inhibition efficiency of 95.59 % at a concentration of 2.00 g/L and a temperature of 298 K. The PDP analysis indicated that EOBH functions as a mixed-type inhibitor. EIS data suggested that the inhibitor interacts with the metal surface via charge transfer, forming a protective layer. The presence of a protective film of the inhibitor on CS surface was detected by the scanning electron microscopy with energy-dispersive X-ray (SEM/EDX). Additionally, theoretical studies utilizing density functional theory (DFT) and Monte Carlo (MC) simulations were conducted, aligning well with the experimental findings.