Corrosion Inhibition of Carbon Steel by Acridine Orange in HCl Solution: Electrochemical and Weight Loss Studies

The inhibition effect of acridine orange (AO) on the corrosion of A105 carbon steel in 0.5 M hydrochloric acid has been investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss tests. Using polarization plots and corrosion rate calculations, it has been revealed that AO acts as an effective inhibitor. The results have showed that the inhibition efficiency increases with increasing inhibitor concentration and A behaves as a mixed type inhibitor in HCl solution. Based on the data obtained from the EIS tests, it has been determined that the charge transfer resistance increased from 74.20 Ω.cm² for blank solution to 250 Ω.cm² for 100 ppm of AO. Comparison of the results obtained from the three methods, have shown that the methods are in acceptable agreement. Investigation the effect of temperature in the range of 20-60 °C has indicated that the inhibition efficiency increased with temperature, so that at 40 and 60 °C, the inhibition efficiency would reach 90%. The thermodynamic parameters of steel dissolution including activation energy, standard enthalpy and entropy of activation have been calculated and discussed. It was also found, that the adsorption of AO on the steel surface has obeyed Langmuir isotherm and adsorption has been performed spontaneously.