Corrosion inhibition performance of imidazoline derivatives with different pedant chains under three flow rates in high-pressure CO2 environment

Abstract

Six imidazoline derivatives with different pedant chains were synthesized using oleic acid and different amines respectively to be used as corrosion inhibitors. The hydrophobicity/hydrophilicity was discussed using contact angle and atomic force microscopy curve measurement. The inhibition performance was investigated by weight loss method and scanning electronic microscopy at different flow rates in a high-pressure CO2 environment. The results showed that the hydroxyethyl group in the pedant chain can improve the hydrophilicity of imidazoline, while amino ethylene can improve the hydrophobicity of imidazoline. Increasing the number of amino ethylene units causes a gradual increase in the hydrophobicity of imidazoline. The hydrophobic performance of imidazoline synthesized by oleic acid and polyethylenepolyamine was the strongest. The dynamic weight loss experiment showed that the inhibition ability of imidazoline derivatives was affected both by the structure of imidazoline derivatives and flow rate of fluid. Under low velocity (0.3 and 0.6 m/s), the highest inhibition efficiency was gained by the derivative with two amino ethylene units in pedant chain, while under high flow velocity (5.5 m/s), the imidazoline derivatives with multiple amino ethylene units (more than 3) ranked the highest. The inhibition efficiency of inidazoline was decreased by the introduction of hydroxyethyl group to the imidazoline ring. The inhibition behaviors were explained by hydrophobicity–hydrophilicity balance of imidazoline derivatives.