Adsorption kinetics of benzyl triphenyl phosphonium chloride on mild steel in 1N sulphuric acid

The inhibitive effect of benzyl triphenyl phosphonium chloride (BTPPC) on the corrosion of mild steel in aerated 1N sulphuric acid at different temperatures was investigated using galvanostatic polarisation, potentiostatic polarisation, infrared spectroscopy, scanning electron microscopy and quantum chemical studies. Corrosion potential, corrosion currents, cathodic and anodic Tafel slopes, heat of adsorption and effective activation energies were calculated in the presence and absence of the BTPPC. Inhibition efficiencies of BTPPC at different concentrations and temperatures were studied. The nature of the adsorption of BTPPC on metal surface was also examined. It is concluded that the passivation parameters depend on the presence of the already adsorbed anions. BTPPC is one of the rare inhibitors that only passivate the metal at lower concentrations while passivation at higher concentrations is not observed. The electrochemical data fit Temkin's isotherm. The results of surface morphology and quantum chemical analysis are in agreement with the electrochemical results.