Evaluation of Alpinia galanga and its active principle, 1'-acetochavicol acetate as eco-friendly corrosion inhibitors on mild steel in acidic medium

Abstract

Plant extracts as corrosion inhibitors have been expansively explored and are found as an alternative to synthetic organic compounds. Crude hexane extract of Alpinia galanga rhizome and its major active constituent namely, 1'-acetochavicol acetate were investigated for their corrosion inhibition properties on mild steel in hydrochloric acid solution using weight loss, electrochemical and quantum chemical methods. Potentiodynamic polarization investigations revealed that the inhibitors performed as mixed inhibitors. The highest inhibition efficiency of 90.2% was achieved for crude hexane extract while 84.6% was obtained for 1'-acetochavicol acetate. The quantum chemical parameters calculated for 1'-acetochavicol acetate as the major compound of the plant gave good correlation with the experimental results. The effectiveness of the inhibitors was also supported using field emission scanning electron microscopy (FESEM). The mechanism of interaction of both the inhibitors on mild steel surface was found to conform to the Langmuir adsorption isotherm.