Gloriosa superba Linn. Extract as Eco-friendly Inhibitor for Mild Steel in Acid Medium: A Comparative Study

摘要

The comparative studies of various parts of the plant Gloriosa superba Linn, extract (leaves, flowers, stems, tubers) were carried out to investigate the corrosion protection efficiency on the corrosion of mild steel in 1 N HC1 medium by using mass loss method, polarization measurements and electrochemical impedance spectroscopy at room temperature. Polarization measurements showed that the studied extract acts as mixed type inhibitor with significant reduction of cathodic and anodic current densities. Organic moieties present in the extract are found responsible for effective performance of inhibitor which is well supported by FTIR studies. On comparison, optimum inhibition efficiency was found in Gloriosa superba Linn, stem extracts with 99.80 % at 15 ppm concentration. The nature of protective film formed on the mild steel surface has been confirmed by SEM analysis. The surface coverage values fits well to the Temkin adsorption isotherm.