An electrochemical study of carbon steel CO2 corrosion in the presence of monoethylene glycol: The effects of pH and hydrodynamic conditions

50 and 80 wt.% monoethylene glycol (MEG)/water mixtures at pH 4 and 6 were tested under different hydrodynamic conditions to investigate the MEG effects on CO2 corrosion of carbon steel. At pH 4, the presence of MEG resulted in a lower and less flow-dependent corrosion current density (icorr) than those of aqueous solutions. Since MEG changed the physical properties of the solution, it evidently led to a hindered transport of H+ ions to the steel surface and the decreased corrosion kinetics. At pH 6, icorr was slightly increased with shear stress in water-only and 50 wt.% MEG solutions, while it was decreased at 80 wt.% MEG concentration. It was found that at pH 6, MEG predominantly inhibited corrosion by anodic adsorption on the active sites and blocking the ionic transport.