Inhibition of steel corrosion in HCl media by phosphite compound

Purpose – The purpose of this paper is to investigate the inhibitive effect of the phosphite NaCo(H2PO3)3•H2O (PhCo) for the corrosion of mild steel in HCl solutions. The study is another trial to find a mineral inhibitor for mild steel corrosion.Design/methodology/approach – The inhibitory effect has been evaluated by gravimetric and polarisation techniques at various temperatures. The type of adsorption inhibition and adsorption and kinetic data are determined.Findings – Results show that PhCo inhibits the corrosion of steel in acidic solution. The inhibition efficiency at 308 K increases with the inhibitor concentration to reach 96 per cent for 10−4 M, and then decreases at higher temperatures. Kinetic parameters such as Ea, ΔHa ∘ and ΔSa ∘ were calculated. The adsorption of inhibitor obeys the Langmuir isotherm model. Thermodynamic parameters of adsorption including ΔGad, ΔHad, ΔSad, and Keq(ad) were calculated in the presence of inhibitor.Research limitations/implications – Electrochemical studies (p...

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