A Highly Effective Corrosion Inhibitor by Use of Gemini Imidazoline

Summary Corrosion inhibitors are widely used to control corrosion under the sweet and sour environments in the oil and gas industry. More effective and environmentally friendly corrosion inhibitors need to be developed. This paper studies a new gemini imidazoline (GIM) corrosion inhibitor, in which two hydrocarbon chains and two head groups are linked by a rigid spacer. The GIM was synthesized through the reaction of oleic acid with triethylene tetramine at 2:1 molar ratio. The performance of the GIM on inhibition of carbon dioxide (CO2) corrosion was evaluated by linear polarization resistance in sparged-beaker testing. Rotating-wheel testing was performed to evaluate the film persistency of the test inhibitors. The results showed that corrosion inhibition of the GIM was more effective at lower concentration than that of conventional imidazoline. The mixture of GIM and fatty acid also showed better film persistency than conventional imidazoline. The emulsion tendency of the GIM was less than that of conventional imidazoline. The mechanism of the highly effective GIM was studied. It showed that GIM has much-higher surface activity than conventional imidazoline. The critical micelle concentration (CMC) of GIM is several times lower than that of conventional imidazoline. Hence, the new GIM corrosion inhibitor and its mixture give more-effective corrosion inhibition at low concentration; there is also a lesser environmental effect.