The Corrosion Inhibition Potential of Carbonized Orange Peel (COP) Extract as an Inhibitor for Mild Steel in Acid Solution

Abstract

This study explores the corrosion inhibition potential of carbonized orange peel (biomass) extract as an inhibitor for mild steel in acid solution, offering a low-cost, renewable alternative to conventional synthetic inhibitors. The extract, rich in polyphenols and oxygenated compounds, was prepared in 0.1M Hydrochloric (HCl) acid solution at 50°C and investigated via weight loss technique.

UV–Visible spectroscopy showed progressive absorbance reduction with immersion time, indicating adsorption of active molecules. FTIR confirmed the preservation of O–H, C=O, and C–O–C groups in the surface film, suggesting stable interfacial attachment without structural degradation. Electrochemical analyses revealed mixed-type inhibition behaviour, with significant reductions in corrosion current density and increased charge transfer resistance, consistent with barrier film formation.

SEM imaging confirmed surface protection, showing reduced pitting and smoother morphology compared to the uninhibited steel. The results indicate a predominantly physisorption mechanism, possibly enhanced by weak chemisorption. Comparable to literature-reported biomass inhibitors, this system offers environmental compatibility and economic advantages, demonstrating the potential of agricultural waste valorization for industrial corrosion control in acidic environments.