Evaluation of Benzyl Triphenyl Phosphonium Chloride as Corrosion Inhibitor for Mild Steel in Phosphoric Acid

摘要

The effect of Benzyl triphenyl phosphonium chloride (BTPPC) on the corrosion of mild steel in asolution of 0.3 M phosphoric acid has been investigated at various inhibitor concentrations andtemperatures by Potentiodynamic Polarization Studies, Potentiostatic Polarization Studies,Electrochemical Impedance Spectroscopy Studies (EIS), Temperature Kinetic Studies and ScanningElectron Microscopy (SEM). Results obtained from Potentiodynamic polarization studies reveal thatBTPPC is a mixed type inhibitor for mild steel in 0.3 M phosphoric acid. Potentiostatic polarizationstudies show that BTPPC is a non-passivating type of inhibitor. The corrosion behavior of steel in 0.3M H3PO4 with and without the inhibitor at various concentrations was studied in the temperature rangefrom (298.15 to 338.15) K. The inhibition efficiency increases with an increase in concentration at alltemperatures. The inhibition efficiencies decrease with an increase in temperature for lower-3 concentrations of BTPPC, but for the higher concentration such as 110 M, inhibition efficienciesdecrease with an increase in temperature up to 318.15 K and then increase with a further increase intemperature up to 338.15 K. The adsorption of BTPPC accords to the El-Awady adsorption isotherm.Kinetic and thermodynamic parameters such as effective activation energy (Ea), Gibbs free energy ofo o adsorption ( ads) and heat of adsorption (咹 ads) indicate that adsorption of BTPPC on the mild steelsurface is primarily physical in nature. The results of scanning electron microscopy are in agreementwith the electrochemical analysis results.