Effect of henna in ethanol for the inhibition of aluminium in seawater at low concentration

Abstract

Aluminium alloy type 5083 or AA5083 is known for exceptional performance in extreme environments. AA5083 shows an excellent corrosion resistance mostly in seawater and industrial chemical environment. Nowadays, corrosion is entrenched in maritime industry where the ship plate undergoes corrosion and it depends on the different environment. As a remedy, natural inhibitor was used to overcome this problem. This study used plant extract which is henna (Lawsonia Inermis). Henna was extracted with ethanol as solvent by using rotary evaporator (Rotavap ). Low concentration of henna which is 100, 200, 300, 400 and 500ppm was used. The characterization of the corrosion was performed by using potentiodynamic polarization (PP), weight loss, electrochemical impedance spectroscopy (EIS), fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The percentage of inhibition efficiency (IE %) was calculated by using equation and this study showed the corrosion rate increase by decreasing concentration of the henna extract. This extract is believed to form a surface layer as it protects AA5083 from reacting to the environment.