Corrosion behaviour of aluminium in the presence of an aqueous extract of hibiscus rosa-sinensis

Abstract

The inhibition efficiency (IE) of an aqueous extract of Hibiscus rosa-sinensis (white) in controlling corrosion of aluminium at pH 12 has been evaluated by weight loss method in the absence and presence of Zn2+. The formulation consisting of 8 mL flower extract (FE) and 50 ppm of Zn2+ had 98% inhibition efficiency. Polarization study revealed that this formulation functioned as cathodic inhibitor. AC impedance spectra revealed the presence of a protective film formed on the metal surface. FTIR spectra revealed that the protective film consisted of a complex formed between the active principle of the flower extract and Al3+.