Synergistic inhibition behavior of an imidazoline derivative and halide ions during CO2 corrosion on carbon steel

摘要

The corrosion inhibition of carbon steel was studied by using an amido-imidazoline derivative and halide ions as an additive in CO_2-saturated 3% NaCI solution with electrochemical techniques. The corrosion rate of the steel decreased with increase in the studied inhibitor concentration, while the inhibition efficiency increased and synergistically enhanced on addition of iodide ions. The values of synergism parameter found to be greater than unity. The experimental results revealed that the presence of iodide ions in the solution stabilized the adsorption of imidazoline molecules on the steel surface thereby improving the inhibition efficiency of the inhibitor. Furthermore, the adsorption of amido-imidazoline on the steel surface followed the Langmuir adsorption isotherm and it was chemically adsorbed on the surface of steel. The synergistic effect of iodide ions and amido-imidazoline was due to co-adsorption of iodide ions and amido-imidazoline molecules which was synergistic in nature.