Green approach to inhibition of corrosion of aluminum in 0.5 M HCl medium by tender arecanut seed extract: insight from gravimetric and electrochemical studies

Abstract

Tender arecanut seed (TAS) extract was assessed for its ability to hinder aluminum corrosion in 0.5 M HCl medium by means of gravimetric, polarization, and impedance techniques. Gravimetric experiments revealed an anticorrosive effect of extract constituents on aluminum surface, with the inhibition efficiency becoming more pronounced as the TAS extract concentration was increased but subdued as the exposure period was lengthened. Adsorption of TAS extract on aluminum surface was well fit by the Langmuir isotherm model. The inhibitory modality of TAS extract was elaborated in detail based on kinetic and thermodynamic calculations. Polarization studies revealed that TAS extract functioned as an inhibitor by decreasing corrosion current densities through a mixed-mode mechanism, and alternating-current (AC) impedance spectroscopy results evidenced adsorption of organic species from the extract at the aluminum–acid interface. Morphological studies of aluminum surface were carried out by atomic force microscopy. The inhibition efficiency values obtained by electrochemical measurements were consistent with those from gravimetric measurements and reflect the potential of TAS extract for corrosion inhibition of aluminum in acidic systems.