Evaluation of the Inhibitive Effect of African Marigold (Tagetes erecta L.) Flower Extracts on the Corrosion of Aluminium in Hydrochloric Acid

Abstract

Corrosion inhibition of Aluminium coupon in acidic medium using flower extract of marigold (Tagetes erecta L) in 0.5M HCl solution was investigated using weight loss technique which is considered more informative than other laboratory methods. Aluminium sheets of purity 98.98%, each sheet was 0.1 cm in thickness and cut into coupons of dimension 6cm x 3cm and was decreased by washing with absolute ethanol, dried in acetone. These rectangular test coupons were totally immersed in the acid solution containing the various concentration of the inhibitor at the time intervals of 5-25 hours. The maximum values of the inhibition efficiency of 90.2%, 90.1%, and 90.1% were obtained at the concentration of 3.4ml, 4.5ml and 5.6ml for 5hours immersion time respectively. The corrosion rate was found to decrease tremendously and it was also observed that the inhibition efficiency (%) increased with an increase in the volume of the extracts. The corrosion inhibition is probably due to the adsorption
 f the phytochemical constituents of the extract on the metal surface and blocking its active sites by the phenomenon of chemical
adsorption. The study showed that the flower extract of Targets erecta L. in 0.5M HCl possesses inhibiting properties for reducing the corrosion rate of aluminium.