GCMS Studies On Anogessus Leocarpus (Al) Gum and Their Corrosion Inhibition Potential for Mild Steel in 0.1 M HCl

GCMS study of Anogessus leocarpus gum (AL gum) indicated the presence of sucrose (10.03 %), phthalic acid (2.53 %), n-hexadecanoic acid (11.73 %), oleic acid (30.49 %), pentacenequinone (4.41 %) and 2,3- diphenylnaphthoquinone (21.43 %). The gum was found to be a good adsorption inhibitor for the corrosion of mild steel in HCl solution. The adsorption of the inhibitor on mild steel surface is exothermic, spontaneous, Langmuir type and supports the mechanism of charged transfer from the inhibitor’s molecule to the charged metal surface. FTIR study of the AL gum and the corrosion product of mild steel (in the presence of AL gum as an inhibitor) indicated the presence of interaction between the inhibitor and the metal surface (some shifts in frequencies of IR adsorption), some functional groups were used for the adsorption of the inhibitor onto the metal surface (missing functional groups) and others for the formation of Fe-inhibitor complex (new functional groups formed). The inhibition of mild steel corrosion is proposed to occur through synergistic combination of the constituents of the inhibitor, which facilitates the formation of multi-molecular layer of adsorption and the formation of inhibitor-metal complex, which protected the metal from further corrosion attack.