Protection of mild steel from corrosion in HCl solution via green Rumex acetosella extract: Experimental and theoretical studies

The efficiency and potential of green Rumex acetosella extract (RAE) RAE ) on the inhibition of the mild steel (MS) corrosion were investigated in the acidic environment. The high inhibitive capability of RAE on the mild steel was studied by electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. In addition, potentiodynamic (PD) polarization measurements were carried out to examine corrosion mechanism. The achieved electrochemical tests showed that RAE has a significant inhibition effect on mild steel corrosion. The results of surface analysis recorded by scanning electron microscopy (SEM), and atomic force microscopy (AFM) depicted that RAE provide strong protective layer on the steel surface via adsorptive groups. The inhibition efficiency was calculated as 99.7 %, and 99.6 % from LPR and EIS after 120 h exposure time. Adsorption free energy ( Delta G oads ) value is found as-29.79 kJ mol-1,- 1 , indicating that both physical and chemical adsorptions occur. Furthermore, the obtained experimental findings were supported with quantum chemical calculation results.