Methanol extract of Murraya koenigii stem as green inhibitor for mild steel corrosion in 1 M HCl solution

Abstract

In this work, methanol extract of Murraya koeginii stem has been studied as an ecofriendly inhibitor against mild steel corrosion in 1 M hydrochloric acid medium. Ultraviolet–visible and Fourier transform infrared spectroscopic tools were employed to characterize the extract. Corrosion inhibition efficacy of the extract against mild steel was studied in terms of weight loss method and electrochemical measurement method. Weight loss measurement shows the inhibition efficiency of 94.95 % for the first 6 h of immersion time and maximum efficiency of 96.39 % for 24 h immersion time using 1000 ppm inhibitor solution. Electrochemical measurement shows that for the same concentration of inhibitor, inhibition efficiency is 81.54 % in as-immersed condition whereas it is 85.76 % in 1 h immersed condition. Free energy of the adsorption reflected the physisorption followed by chemisorption. Similarly, thermodynamic parameters revealed the feasibility and spontaneity of the adsorption. Obtained results showed that the methanol extract of Murraya koeginii stem can be a potential corrosion inhibitor.

Keywords

• Murraya koeginii
• Green inhibitor
• Weight loss
• Polarization
• EIS