Effect of cations on the activity coefficient of NO2–/NO3– corrosion inhibitors in simulated concrete pore solution: An electrochemical thermodynamics study

Abstract

The effect of Na+ and Ca2+ cations on the chemical activity of NO2–/NO3– corrosion inhibitors on carbon steel rebars were studied in 0.6 M Cl– simulated concrete pore solution. The activity coefficients were calculated using the Pitzer virial coefficient approach. The Ca2+ ions induce more ionic interactions compared to Na+, because of its multivalent charge nature. The modeling results were supported through an experimental electrochemical thermodynamics study by potentiodynamic polarization and electrochemical impedance spectroscopy at 25, 35, 45, and 55 ºC. In conclusion, Ca2+ ions decrease the chemical activity and activity coefficients of NO2–/NO3–, which hinders their mobility and inhibition efficiency.