Journal of Chemical and Pharmaceutical Research (ISSN : 0975-7384)

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Original Articles: 2016 Vol: 8 Issue: 2

Corrosion inhibition effect of Allium sativum extracts on mild steel in HCl and H2SO4


The effect of Allium sativum(garlic) extract as a ‘green’ inhibitor on mild steel corrosion in 0.5M HCl and 0.5M H2SO4 was studied at ambient temperature. Weight loss/corrosion rate and potentiostatic polarization measurement techniques were used for the experimental work. Potentiostatic polarization measurement was performed using a potentiostat (Autolab PGSTAT 30 ECO CHIMIE) interfaced with a computer for data acquisition and analysis. Results obtained showed effective corrosion-inhibition of the extract on the mild steel test-specimens in the different concentrations of HCl and H2SO4 used. There was increasing inhibition performance with increasing concentration of inhibitor. The best inhibition performance was achieved with the 100% (as extracted) garlic concentration. In 0.5M HCl, 100% garlic gave the optimal performance with weight loss at 8 days of the experiment of -0.15g, polarization resistance value of 2.78E+03Ω, corrosion rate, CR, of 9.47E – 02 mm/yr and current density (Icorr) value of9.46E-02 A/cm2. A similar result was observed in 0.5M H2SO4 where 100% garlic gave the best results of - 0.145g weight loss, polarization resistance value of2.79E+03Ω;corrosion rate, CR, value of9.46E-02 mm/yr and current density of9.20E-06 mm/yr. Results of ba and bc indicate a mixed type inhibitor.