Authors : O.O. Ajayi, O.A. Omotosho, K.O. Ajanaku and B.O. Olawore
Abstract: Hydrochloric acid induced damage of aluminum alloy in the presence of Cola acuminata extract was investigated using gasometric technique. Aluminum alloy coupons of dimension 4 cm by 1 cm were immersed in test solutions of free acid and also those containing extract concentrations of 2-5 cm3 at ambient temperature for 30 min. The volumes of hydrogen gas evolved as a result of the reaction rate were recorded and analyzed. The outcome revealed that maximum inhibitor efficiency which corresponds to the lowest corrosion rate was obtained at optimum inhibitor concentration with reduction in the corrosion rate observed to follow in order of increasing extract concentration. The mechanism of interaction between the phytochemicals in the plant extract and aluminum alloy surface was best described by the Frumkin isotherm with 6 and 14 min becoming the best exposure time for the phytochemicals in extract concentrations of 3-5 cm3 to suitably adsorb to metal alloy surface. Statistically modeling the corrosion rate yielded a significant relationship suitable for estimating corrosion rate values once concentration of the extract is known. In addition, the superficial analysis revealed that crack growth rate slowed down and irregular intermetallic phases were more uniform as extract concentration increased.
O.O. Ajayi, O.A. Omotosho, K.O. Ajanaku and B.O. Olawore, 2011. Failure Evaluation of Aluminum Alloy in 2 M Hydrochloric Acid in the Presence of Cola acuminata. Environmental Research Journal, 5: 163-169.