Electrochemical Studies of the Inhibition Effect of Vitamin B1 and Bromide Ion on the Carbon Steel Corrosion in Phosphoric Acid Solution

This paper investigates the inhibition effects of Vitamin B1 without and with bromide ion on carbon steel corrosion in 1.0 mol/L phosphoric acid solution using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The results indicate that combination of Vitamin B1 and bromide ion performs excellent as inhibitor for carbon steel corrosion in H3PO4 solution and a stronger synergistic effect exists between Vitamin B1 and bromide ion. The electrochemical studies reveal that single Vitamin B1 acts as a cathodic type inhibitor, but combination of Vitamin B1 and bromide ion shows as a mixed-type inhibitor and the corrosion reaction is controlled by charge transfer process. Adsorption of VB1 on the steel surface obeys Langmuir adsorption isotherm in the absence or presence of bromide ion. The thermodynamic and kinetic parameters (∆ G° ads , ∆ H° ads , ∆ S° ads, K ads and E a ) were calculated and discussed. The adsorption of inhibitor molecules on the steel surface is a spontaneous process and chemical adsorption is absolutely dominant.