Sustainable corrosion protection of copper in H2SO4 medium using garlic extract: Experimental and theoretical approaches

This study aims to explore the anticorrosive properties of Moroccan Allium sativum (garlic) extracts on copper corrosion in a sulfuric acid environment, focusing on both chemical composition and inhibition efficacy. Detailed analysis revealed that the extract is rich in bioactive compounds, particularly polyphenols and flavonoids, including ascorbic acid, gallic acid, vanillin, quinol, and quercetin. These constituents are recognized for their potential to chelate metals, suggesting a protective effect on metal surfaces. Electrochemical measurements were conducted in a 0.5 M H 2 SO 4 solution, where the extract demonstrated mixed-type inhibition behavior, affecting both the anodic and cathodic reactions of the corrosion process. The inhibition efficiency reached an impressive 94%, indicating a substantial barrier effect against copper dissolution. Thermodynamic parameters, including activation energy and enthalpy of adsorption, were analyzed to better understand the adsorption mechanism on the copper surface. These parameters revealed that the inhibition is mainly a result of physisorption, with contributions from chemisorption by certain bioactive compounds. Furthermore, Density Functional Theory (DFT) provided insights into charge-sharing (donor-acceptor) interactions between inhibitor molecules and metallic surfaces. This research highlights Allium sativum extract as a sustainable, effective, and eco-friendly alternative to traditional corrosion inhibitors, with significant potential for development of green anticorrosion treatments for copper in acidic environments.