Investigation of inhibition by 6-bromo-3-nitroso-2-phenylimidazol[1,2-α]pyridine of the corrosion of C38 steel in 1 M HCl

Inhibition of the corrosion of C38 steel in 1 M HCl by 6-bromo-3-nitroso-2-phenylimidazol[1,2-alpha]pyridine (BNPP) has been studied by use of electrochemical impedance spectroscopy and potentiodynamic polarization. BNPP inhibited the corrosion of C38 steel in 1 M HCl solution. Polarization curves show that BNPP acts as mixed-type inhibitor. Changes in impedance (charge-transfer resistance, R-t, and double layer capacitance, C-dl) were indicative of adsorption of BNPP on the metal surface, leading to formation of a protective film. The extent of surface coverage by the inhibitor was determined by measurement of weight loss; it was found that adsorption of this inhibitor on the C38 steel surface obeys the Langmuir adsorption isotherm. The effect of temperature on the corrosion behaviour was studied in the range 289-328 K. The results showed that the rate of corrosion of C38 steel increased with increasing temperature both in the presence of 10(-3) M BNPP and in its absence. Activation energies in the presence and absence of BNPP were obtained by measuring the temperature dependence of charge-transfer resistance.