COMPARATIVE EVALUATION OF GREEN CORROSION INHIBITOR ON MILD STEEL CORROSION IN 1 M HCL AND 0.5 M H2SO4

The effectiveness of Persea americana Seed as a Green Corrosion Inhibitor for Mild Steel in acidic media (1 M HCl and 0.5 M H2SO4) was evaluated by weight loss method. The result showed increasing the concentration of seed extract improved its inhibitory efficiency with an optimum concentration 0.5% (V/V) achieving maximum efficiency of 85 % in 1 M HCl and 79 % in 0.5 M H2SO4. The best immersion time for maximum inhibition efficiency was found to be 3 h for 1 M HCl and 1 h for 0.5 M H2SO4. At 0.5% (V/V) concentration of the inhibitor, the ideal temperature for maximum inhibition efficiency (87%) was 323 K. The study also revealed that the Hydrochloric acid showed synergistic effect whereas Sulphuric acid showed anti-synergistic effect. Adsorption followed Langmuir, Freundlich and Temkin isotherms. The thermodynamic parameters revealed that the inhibition process was spontaneous, exothermic and the interaction between the phytoconstituents and the metal surface took place through physisorption. The probable mechanism has been proposed for the inhibition action and inhibition efficiency follows the order: HCl > H2SO4