Study of the corrosion inhibition of C38 steel in a 1M HCl medium by the ethanolic extract of Rumex Nervosus Vahl leaves

Abstract

Corrosion inhibition effect of Rumex Nervosus Vhal Leaves Extract (RNVLE) on C38 steel in a 1 M HCl medium has been investigated by electrochemical techniques. Inhibition efficiency of (96.0%) and (95.5%) were achieved with (2 g L−1) at ambient temperature. The polarization studies showed that RNVLE acts as a mixed-type inhibitor. The Nyquist plots showed that increasing RNVLE concentration increases charge transfer resistance and decreases double layer capacitance. RNVLE obeys the Langmuir adsorption isotherm. By noting and matching the values of the correlation coefficient R2 of various adsorption isotherms, the adsorption of our inhibitor RNVLE obeys the Langmuir isotherm (R2 = 0.999). RNVLE controls the corrosion process through physisorption, according to the calculated free energy (ΔG0ads = –16.1 KJ mol−1). The impact of immersion time was also studied, this study showed that RNVLE could be a good inhibitor for up to 6 h − where the inhibition efficiency at this time was 94.2% − before becoming a lower-quality inhibitor even though it still has a strong inhibitory effect. The extract molecules adsorb on the surface of the metal, according to SEM-EDX analysis, which combines scanning electron microscopy and X-ray energy dispersive spectroscopy. The RNVLE can be regarded as an effective corrosion inhibitor for C38 steel in 1M HCl solution, according to these results.