Study On The Synthesis Of Amide Imidazoline Quaternary Ammonium Salt And Corrosion Inhibition Performance

A series of water-soluble imidazoline quaternary ammonium salts was synthesized by three steps. First, naphthenic acid and polyamines were used as raw materials, after dehydration and condensation, and then obtained the oil-soluble imidazoline intermediates. Second, the imidazoline intermediates reacted with low carbon fatty acid to form amide imidazolines by amidation. Third, imidazoline intermediates or amide imidazolines reacted with benzyl chloride to obtain the final imidazoline quaternary ammonium salts. The ultimate products all have the same characters that can prove the reaction completely, such as a well solubility in water, p H in 1% aqueous solution about 6.0, amine values close to 0, the characteristic peaks of IR and UV.Studying corrosion inhibition of these series of amide imidazoline quaternary ammonium salts in different corrosive medium. these series of amide imidazoline quaternary ammonium salts had a good inhibitive effect on carbon steel in neutral 18% Na Cl solution,8% HCl solution, 10% H2SO4 solution and 10% H3PO4 solution. In Na Cl, HCl, H2SO4 and H3PO4 solution, the inhibition effect of Ⅲ, ⅣandⅤ was better. And it was Ⅲ that had many advantages. Such as the well water soluble, simply preparation technology, low manufacture cost, the good corrosion inhibition, and widely applied range. After a comprehensive consideration, the inhibitor Ⅲ was chosen as the bsst corrosion inhibitor.Using the weight loss method and electrochemical method to study the corrosion inhibition performance of Ⅲ at carbon steel in corrosive media. Carbon steel coupon experiments showed that the change relationship of the inhibition rate of Ⅲ and drug dose followed some certain rules. Drug dose increased, inhibition rate increased. While the level of the increasing inhibition rate reduced gradually. The corrosion rate tended to stable or decreased slightly when the dosage increased to a certain value. This explained that Ⅲ had a most suitable dosage in the corrosion medium. By controlling to the appropriate conditions, the inhibition rate could reach or above 90%.Electrochemical experiments showed that Ⅲ could prevent not only cathodic reaction but the anodic reaction in 0.2% HCl solution. Which explained that Ⅲ was a mixed type inhibitor that mainly cathode type controlling. The change relationship of corrosion rate and drug dose concluded from Polarization curves and AC Impedance Spectroscopy was consistent with the conclusion of weight loss method.