Corrosion inhibition of steel in acidic media using glycyrrhizic acid: experimental and computational insights

This work shows the utilization of glycyrrhizic acid (GLA) as a corrosion inhibitor for steel within acidic environments. Employing a multifaceted approach, the investigation integrates spectral analysis, thermal testing, electrochemical assessments, surface characterization techniques, and computational modeling to elucidate GLA’s mechanisms of corrosion protection. A pivotal finding of this research underscores GLA’s capacity to engage with metal surfaces through both physisorption and chemisorption mechanisms, facilitated by its inherent functional groups. Moreover, thermal analysis reveals GLA’s robust stability up to temperatures of 170°C, rendering it well suited for applications within moderate-temperature environments. Electrochemical analyses unveil a notable augmentation in charge transfer resistance, escalating from 5.18 to 90.64Ω/cm², alongside a concomitant reduction in corrosion current density from 15.64 to 0.83μA/cm², particularly evident at 200mg/L. Surface examinations corroborate the ameliorated state of surfaces treated with GLA, with discernible compositional alterations indicative of efficacious corrosion inhibition. Adsorption studies align with the Langmuir model, suggesting monomolecular adsorption behavior. Thermodynamic scrutiny reveals a spontaneous and endothermic process, with heightened efficacy observed at elevated temperatures. Lastly, the computational model unveils robust interactions between GLA and the metal surface, characterized by interaction energies reaching as low as −2033.91kJ/mol, thus underscoring the stability inherent in the protective layer formed by GLA.