Joint Effect Of Halide Ions And Ficus Glumosa (FG) Gum Exudate On The Inhibition Of The Corrosion Of Mild Steel In 0.1 M HCL
Corrosion inhibition potential of Ficus glumosa gum exudate for mild steel in 0.1 M HCl was investigated using weight loss and gasometric methods. The results obtained indicated that the inhibition efficiency of Ficus glumosa gum exudate increases with increase in concentration and with increasing temperature. Synergistic combination of the gum and 0.005 M KI, KCl and KBr respectively, led to enhancement of the inhibition efficiency of the gum at 303 K but antagonized the adsorption of the gum at 313, 323 and 333 K (except for I- at 313 K. Activation energies calculated from the Arrhenius equation were relatively low and compromised with a diffusion controlled reaction. Application of the transition state equation indicated that the adsorption of the gum, halides and gum-halide mixture is endothermic and occurred with an increase in orderliness.The adsorption characteristics of the gum revealed a deviation from the ideal Langmuir isotherm due to attractive behavior of the inhibitor. The formation of multiple layers of inhibitor on the surface of the metal was confirmed by slope values greater than unity for El Awardy et al adsorption isotherms. The transfer energy per mole obtained from the Dubinin-Radushkevich isotherm were greater than the threshold value of 8 kJ/mol hence the mechanism of chemisorption was confirmed for the adsorption of Ficus glumosa gum on mild steel surface.
Key words- Adsorption, Corrosion, Ficus glumosa, inhibition, synergism.