Corrosion Inhibition of X70 Pipeline Steel Under Hydrodynamic Conditions of CO₂ with Amide Extraction from Coffee Bagasse

The use of N-[2-[(2-hydroxyethyl)amino]ethyl]-amide, extracted from aminolysis of the fatty acids contained in the coffee bagasse, has been evaluated as a CO₂ corrosion inhibitor for X-70 pipeline steel at different rotating speeds at 50 °C using electrochemical techniques. Rotating speeds were 0, 100, 500, 1000, 2000 and 4000 rpm whereas techniques included potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy (EIS) measurements at an inhibitor concentration of 0 and 25 ppm. Inhibitor was characterized with Infrared spectroscopy and mass/gas chromatography whereas corroded specimens were analyzed with the aid of a scanning electronic microscope. Results have shown that the addition of the inhibitor greatly reduces the corrosion rate. An increase in the rotating speed had a double effect: it increased the inhibitor efficiency at low rotating speeds due to an enhanced inhibitor mass transfer effect, but at high rotating speeds, inhibitor efficiency decreased, due to the detachment of a protective film by the high shear stress.