Carbon dioxide corrosion inhibition of N80 carbon steel in single liquid phase and liquid/particle two‐phase flow by hydroxyethyl imidazoline derivatives

CO2 corrosion inhibition of N80 steel in liquid single‐phase and liquid/particle two‐phase flow by 2‐undecyl‐1‐hydroxyethyl imidazoline (HEI‐11) and 2‐undecyl‐1‐hydroxyethyl‐1‐hydroxyethyl quaternary imidazoline (HQI‐11) was investigated using weight loss, potentiodynamic polarization, EIS, and scanning electron microscope (SEM) techniques. The results show that the corrosion rate in the absence and presence of the imidazolines is strongly dependent on the flow condition and presence of entrained sand particles. The imidazolines function via a mixed‐type corrosion inhibition mechanism. The inhibition efficiencies of the imidazolines followed the trend HQI‐11 > HEI‐11 in all the systems studied. Inhibition mechanism has been discussed in relation to the polycentric adsorption sites on the imidazoline molecules.