CO2 corrosion inhibition of X-70 pipeline steel by carboxyamido imidazoline

The corrosion inhibition of X-70 pipeline steel in saltwater saturated with CO2 at 50 A degrees C with carboxyamido imidazoline has been evaluated by using electrochemical techniques. Techniques included polarization curves, linear polarization resistance, electrochemical impedance, and electrochemical noise measurements. Inhibitor concentrations were 0, 1.6 x 10(-5), 3.32 x 10(-5), 8.1 x 10(-5), 1.6 x 10(-4), and 3.32 x 10(-4) mol l(-1). All techniques showed that the best corrosion inhibition was obtained by adding 8.1 x 10(-5) mol l(-1) of carboxyamido imidazoline. For inhibitor concentrations higher than 8.1 x 10(-5) mol l(-1) a desorption process occurs, and an explanation has been given for this phenomenon.