Experimental Study and Comsol Multiphysics Simulation of Corrosion Inhibition for Mild Steel in Acidic Solutions Using Pteridium aquilinum Extract as Green Inhibitor

Abstract

Corrosion of mild steel in aggressive environments remains a significant challenge in industrial processes. The corrosion behaviour of mild steel in 3 M HCl and its inhibition using an eco-friendly ethanolic extract of Pteridium aquilinum was investigated through combined experimental and numerical approaches. Mild steel specimens (30 × 30 mm, 1.5 mm thickness) were exposed to the acid medium in the presence of varying concentrations of Pteridium aquilinum extract as a green inhibitor for a period of six day. Phytochemical analysis revealed the presence of saponins, alkaloids, tannins, and flavonoids, while FT-IR results confirmed functional groups containing O, N, and S atoms, which act as adsorption centre on the metal surface. Weight loss measurements showed that inhibition efficiency increased with extract concentration but decreased with increase in immersion time. The efficiencies of 94.4%, 93.4%, 83.4%, 76.9%, and 52.5% were obtained at 500, 400, 300, 200, and 100 mg/L, respectively. COMSOL Multiphysics simulation supported the experimental findings, showing good agreement and confirming improved inhibition at higher concentrations, particularly during the initial exposure period. The corrosion protection is attributed to the formation of a protective adsorbed film by the plant extract constituents. Overall, Pteridium aquilinum extract demonstrated effective inhibition performance, especially at higher concentrations, highlighting its potential as an eco-friendly corrosion inhibitor for mild steel in acidic environments.