Boerhavia diffusa (Punarnava) Root Extract as Green Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Solution: Theoretical and Electrochemical studies

摘要

The effect of extract of Punarnava (Boerhavia diffusa) on corrosion of mild steel was investigated bygravimetric, potentiodynamic polarization, electrochemical impedance spectroscopy. Tafelpolarization results revealed that the maximum displacement of -Ecorr value is 46 mV hence the extractacted as mixed-type inhibitor. The inhibition efficiency increases up to 96% at 300 ppm and decreaseswith increase in the temperature. The charge transfer resistance (Rct) value of inhibited system2 2 increased from 68 cm to 426 cm and double layer capacitance (Cdl) value decreased from 37-2 -2 Fcm to 17 Fcm with increasing inhibitor concentration. Langmuir adsorption isotherm wasfollowed by the inhibitor molecules on steel surface. The low value of energy gap () furtherprovided support for high efficiency of the extract.