The inhibition efficiency and adsorption characteristics of alkaloids, flavonoids
and tannins extracts of Mangifera indica
leaves in controlling corrosion of Zinc sheet in 5 M
hydrogentetraoxosulphate (VI) acid solution has been evaluated by gasometric method. The
formulation consisting of 2 g/L of extract offers 96.2%, 85.3% and 70.6% inhibition
efficiencies (alkaloids, flavonoids and tannins respectively) at 30°C to Zinc metal immersed
in 5 M hydrogentetraoxosulphate (VI) acid solution. Judging from the trend in inhibition
efficiency against temperature, it can be deduced that the adsorption process was physisoption
being that corrosion rate increased while inhibition efficiency decreased with temperature.
Adsorption mechanism followed the Langmuir adsorption isotherm being that the correlation
coefficient was found to be approximately unity i.e. 0.9237.