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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.

Ficus platyphylla gum exudates (FP gum) have been analyzed for their physicochemical parameters and found to be ionic, mildly acidic, odourless, and yellowish brown in colour. e gum is soluble in water, sparingly soluble in ethanol, and insoluble in acetone and chloroform. e nitrogen (0.39%) and protein (2.44%) contents of the gum are relatively low. e concentrations of the cations were found to increase according to the following trend, Mn>Fe>Zn>Pb>Cu>Mg>Cd>Ca. Analysis of the FTIR spectrum of the gum revealed vibrations similar to those found in polysaccharides while the scanning electron micrograph indicated that the gum has irregular molecular shapes, arranged randomly. e intrinsic viscosity of FP gum estimated by extrapolating to zero concentrations in Huggins, Kraemer, Schulz-Blaschke, and Martin plots has an average value of 7 dL/g. From the plots of viscosity versus shear rate/speed of rotation and also that of shear stress versus shear rate, FP gum can be classi�ed as a non-Newtonian gum with characteristics-plastic properties. Development of the Master_s curve for FP gum also indicated that the gum prefers to remain in a dilute domain (C < C *), such that sp C 1.2. e apparent activation energy of �ow for FP gum (calculated from Arrhenius-Frenkel-Eyring plot) was relatively low and indicated the presence of fewer inter-and intramolecular interactions.

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The effectiveness of 3-nitrobenzoic acid towards the inhibition of the corrosion of mild steel and aluminium in solution of HCl was investigated using theoretical and experimental methods (weight loss, thermometric, polarization, FTIR and SEM techniques). Inhibition efficiency of 3-nitrobenzoic acid, evaluated from weight loss technique ranged from 71% to 90% and from 71% to 82% for mild steel and aluminium, respectively. Results from linear polarization and potentiodynamic studies were comparable to weight loss results. Calculated kinetic (activation energy), thermodynamic (changes in entropy and enthalpy) and adsorption parameters indicated that the adsorption of the inhibitor on the surface of the respective metal is accompanied by molecular association and is endothermic, spontaneous and favoured the mechanism of physical adsorption. Best-fitted adsorption isotherms were Langmuir and Frumkin models, which gave evidences for the existence of interaction, characterized by attractive behaviour of the inhibitor on both mild steel and aluminium surfaces. Scanning electron micrographs of the metal before and after inhibition clearly revealed that the inhibitor prevented crevice and pitting corrosion by forming adsorbed protective layer on the respective metal surface. FTIR spectra of the inhibitor and the corrosion products indicated the formation of new bond, existence of interaction between the inhibitor molecules and the involvement of some functional groups in the adsorption and inhibition processes. Quantum chemical study revealed that the inhibitor is adsorbed on the metal surface through the nitro functional group in the ring. Calculated semi empirical parameters were comparable to those reported for excellent corrosion inhibitors.

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Examination of the physical (colour, odour, pH, solubility in various solvents) and chemical (GCMS and FTIR) characteristics of Ficus benjamina gum revealed that the gum is yellowish in colour, mildly acidic and ionic in nature. Major constituents of the gums were found to be sucrose and d-glucose, which constituted 60.92 % of their chemical constituents, while various carboxylic acids [(albietic acid (1.00%), hexadecanoic acid (4.41 %), 9-octadecanoic acid (1.00 %), octadecanoic acid (3.01 %), oleic acid (0.10 %), octadecanoic acid (9.12 %) and 6,13-pentacenequinone (20.43 %)] accounted for the remaining constituents. Functional groups identified in the gum were found to be those typical for other carbohydrates. From the knowledge of the chemical structures of compounds that constitute the gum, the corrosion inhibition potentials of the gum were ascertained and from weight loss analysis, the gum was found to be an active inhibitor against the corrosion of aluminum in solutions of tetraoxosulphate (VI) acid. The gum acted as an adsorption inhibitor that favours the mechanism of chemical adsorption and supported the Frumkin and Dubinin-Radushkevich adsorption models.