journal of kerbala university

Abstract

This study was a trial to find an organic inhibitor that can to easily be prepared and applied , as well as non- toxic , cheep and available. In the present study an aqueous extract of tobacco leaves as corrosion inhibitor to protect α brass alloy in acid solutions (hydrochloric and nitric acid) at 1 M concentration, the inhibitor efficiency was evaluated using the weight loss method and microscopic test. Results obtained reveal that the extract of tobacco leaves plants at various concentration (0.5, 1.5, and 3) vol. % show significant corrosion inhibition during immersion of brass in acid solutions. The inhibition efficiency increased with increasing concentration of the inhibitor, but decrease with increase in exposure time. Inhibitor efficiency in 1M HCl and 1M HNO3 at ( 3%) concentration of inhibitor reached to 75.64% and 73.17% respectively. Microscopic examination test shows the clearness of the metals surface which is under the corrosion medium and which contains inhibitor, from any kind of corrosion that can be found on those surfaces, which are under mediums completely empty from inhibitor, and also shows the clearness of that protect layer on the surface. The data of corrosion rate show that the way of doing this organic inhibitor is adsorbing and the inhibitor molecules are adsorbed on the metal surface according to Langmuir adsorption isotherm.