Author(s)

Makanjuola Oki, Ebitei Charles, Collins Alaka, Tambari Kayode Oki

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Studies on the corrosion behaviour of mild steel electrodes in inhibited hydrochloric acid are described. Conventional weight loss measurements show that a maximum concentration of 140 ppm of tannin from Rhizophora racemosa is required to achieve 72% corrosion inhibition. Similar concentration of tannin: H₃PO₄ in ratio 1:1 gave 61% inhibition efficiency, whereas efficiency obtained for phosphoric acid as inhibitor in the same environment was 55%. Corrosion rates obtained over six hours of exposure in 1M HCl solution at inhibitor concentrations of 140 ppm are 2 mA/cm², 2.4 mA/cm², 2.6 mA/cm² and 6 mA/cm² for tannin, tannin/H₃PO₄ and H₃PO₄-inhibited and uninhibited specimens respectively. Natural atmospheric exposure studies revealed that specimens treated in H₃PO₄ resisted corrosion for three weeks, while tannin treated specimens suffered corrosion attack after one week of exposure tests.

Inhibitor, Tannins, Corrosion Rate, Rhizophora Racemosa, Phosphoric Acid

Oki, M. , Charles, E. , Alaka, C. and Oki, T. (2011) Corrosion Inhibition of Mild Steel in Hydrochloric Acid by Tannins Rom Rhizophora Racemosa. Materials Sciences and Applications, 2, 592-595. doi: 10.4236/msa.2011.26079.