Efficiency of sapota leaf extract against aluminium corrosion in a 3 M sodium hydroxide hostile fluid atmosphere: a green and sustainable approach

Abstract

The present study focussed on the performance of a sapota leaf extract in controlling the aluminium (Al) corrosion in 3 M sodium hydroxide (NaOH) medium thoroughly investigated through gasometric, atomic absorption spectroscopy, electrochemical Tafel diagrams and impedance spectroscopy techniques. The outcome shows that small amounts of the sapota leaf extract are sufficient for the effective mitigation of the Al corrosion process in 3 M NaOH solution. The gasometric data revealed that four different concentrations of the plant extract inhibit the Al corrosion process and the protection efficiency of the inhibitor varies with time of the system. Type of inhibition was studied by an electrochemical potentiodynamic polarization technique. The alternating current impedance spectroscopy results show that the plant extract inhibits the corrosion process by forming a defensive layer on the Al surface through an adsorption process, which confirms the inhibition properties of the plant extract. The presence of electron rich groups in the sapota leaf extract was confirmed by the Fourier transform infrared and energy-dispersive X-ray spectroscopy techniques. The particle size of the sapota leaf extract can be analysed by an X-ray diffraction technique. Further, atomic force microscopy and contact angle results evidence the adsorption of the sapota leaf extract on the Al surface. The morphology of the Al surface in protected and unprotected systems was examined through scanning electron microscopy techniques.