Abstract

Corrosion and plants extracts inhibitive protection of mild steel specimens immersed in 0.5 M hydrochloric acid was investigated at ambient temperature by gravimetric and metallographic methods. Extracts of kola plant and tobacco in different concentrations were used as ‘green’ inhibitors. This paper reports the results obtained from the weight loss method, calculated corrosion rates, inhibitor efficiencies and the metallographic observations from metallurgical microscopy. Addition of different concentrations of the plants extracts gave considerable reduction in the weight loss and in the corrosion rate of the test samples. This apparent corrosion inhibition was associated with the protective film provided on the steel’s surface by the complex chemical constituents of the plants extracts. Effective protection of the mild steel was achieved more from the tobacco extract and also from the extract of kola leaf.

Key words: Inhibition, corrosion, mild steel, kola tree, tobacco, hydrochloric acid, protection.