Gas chromatography mass spectrophotometer (GCMS) analysis of Ficus tricopoda gum indicated the presence of 4.75, 56.15, 32.10 and 7.00 % of camphene, sucrose, 2methylene cholestan-3-ol and 7-hexadecenal, respectively. Several stretching and bending vibrations were observed in the Fourier transformed infra-red (FTIR) spectrum of the gum. Physicochemical examinations of the gum revealed that it is pale yellow in colour, mildly acidic, ionic and display characteristics of sour taste. The solubility of the gum in water was found to increase with increase in temperature. Knowledge of the chemical constitution of the gum (hence chemical structures of its constituents) was useful in predicting the corrosion inhibition potential of Ficus tricopoda (FT) gum. Consequently, the gum was found to be a good adsorption inhibitor for the corrosion of aluminum in solution of H 2 SO 4. The adsorption of the gum (which, followed first order kinetic) was found to be endothermic at FT gum critical concentration of 0.3 g/L and exothermic at concentrations above the critical limit. The short coming of the Langmuir adsorption model in describing the existent of interaction between the molecules of the gum was complimented by the Frumkin and Dubinin-Radushkevich adsorption models. Calculated values of activation and free energies of activation indicated that the adsorption of Ficus tricopoda gum on Al surface exhibited both physical and chemical adsorption mechanism.

The inhibitive and adsorption properties of ethanol extract of Hibiscus sabdariffa calyx were studied using gravimetric, gasometric, thermometric, and Fourier transform infrared methods of monitoring corrosion. The results obtained indicated that ethanol extract of Hibiscus sabdariffa calyx is a good adsorption inhibitor for the corrosion of mild steel in HCl solutions. The adsorption of the inhibitor on mild steel surface is spontaneous and supports the Langmuir adsorption model. From the calculated values of free energy of adsorption, the activation energy, and the variation of inhibition efficiency with temperature, it can be concluded that the initial mechanism for the adsorption of ethanol extract of Hibiscus sabdariffa calyx on mild steel surface is physical adsorption. Analysis of spectra obtained from the Fourier transform infrared spectrophotometer indicated that there is an interaction between iron in mild steel and the inhibitor.