Chemical components of mature areca nut husk extract as a potential corrosion inhibitor for mild steel and copper in both acid and alkali media

Mature areca nut husk (MAH) extract was tested for its efficacy anticorrosive property at electrode–electrolyte interface through chemical and electrochemical techniques. Results of weight loss study show that maximum inhibition action of MAH extracts for copper and mild steel in both acid and alkali media was observed at 303 K with the contact time of 1 hour (94.347% for mild steel in 0.5 M HCl medium, 91.666% for mild steel in 0.5 M NaOH medium, 93.750% for copper in 0.5 M HCl medium, and 90.000% for copper in 0.5 M NaOH medium). Protection efficiency values are inverse relationship with the temperature, which indicates the physical nature of protective film on the metal surface. Adsorption characteristics of the MAH extract on the electrode surface in a hostile fluid environment are consistent with the Langmuir isotherm model under study conditions, which indicates the monolayer formation of inhibitor on electrode surfaces. Results of Tafel study confirm that MAH extract acts as an effective anodic type of inhibitor for the system copper in 0.5 M NaOH system, in the rest of the cases, it acts as a mixed type of inhibitor. From the Nyquist plot, it is clear that increased depressed semicircle area with an increase in MAH extract concentration is an evidence of the inhibitory role of plant extracts on the metal surface. Further, Fourier transform infrared spectroscopy and scanning electron microscopy techniques clearly indicated the protective film-forming ability of the MAH extract on the metal surface.