Mangifera indica Leave Extracts as Organic Inhibitors on the Corrosion of Zinc Sheet in 5 M H2SO4 Solution

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\ub0C 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