Natural Compounds Onion (Allium Cepa), Garlic (Allium Sativum) and Bitter Gourd (Momordica Charantia) as Corrosion Inhibitors for Mild Steel in Hydrochloric Acid

摘要

Corrosion and its inhibition study of mild steel in HCl (5%) was carried out using three naturally occurring compounds. Evaluations of the inhibitors was done by different techniques. Three D.C Electrochemical techniques, (a) Tafel extrapolation (b) Resistance polarisation and (c)" Vicor" method, a computer added software programme, were used. Classical weight loss and dissolved iron concentration in bulk solution were measured and corrosion rate were also calculated on the basis of iron concentration. Acid extract of three naturally occurring substances (1) onion (Allium cepa) (2) Garlic (Allium sativum) and (3) Bitter gourd (Momordica charantia) were studied for efficiency of inhibition. Variable parameters like inhibitor concentration, immersion period, temperature, and stirring rate were incorporated. 1% inhibitor concentration in 5% HCl gave 82%, 98% and 88 % inhibition efficiency respectively. The logarithm corrosion rate vs reciprocal Abs. temperature was linear in presence of inhibitors. The linear plot relating logarithm inhibitor concentration and logarithm degree of coverage of inhibitor confirmed that Freundlich adsorption equation is applicable and supported the mechanism of inhibition as being chemisorption.