Corrosion Inhibition by a Caesalpinia Sappan L Modified Imidazoline for Carbon Steel API 5L Grade X60 in HCl 1M Environment

Abstract

Acidizing is one of the stimulation technologies in the oil and gas industry by removing scale, rust, debris or other acid-soluble particulates on the pipe tubing internal surface. The most common acid used is HCl. To avoid problems such as pipe or casing tubing leak due to acidic corrosion, during the acidizing normally applied with inhibition treatment by inorganic corrosion inhibitor with various compositions including quaternary ammonium salts, solvent and often some surfactant to strip oil from acid reactive surfaces. However, most of these compounds are not only expensive but also toxic to the marine environment. It is an obvious remark to point out the importance of low cost, green corrosion inhibitors which is safe to the environment. The wood extract has become important as an environmentally acceptable, readily available and renewable resource for wide range of inhibitors. A Caesalpinia Sappan L modified imidazoline has been synthesized and used as a corrosion inhibitor for carbon steel in API 5L X60 in HCl 1M environment.The aim of the investigation is to find low dosage-high efficiency green corrosion inhibitor.The testing techniques include wheel test weight loss measurement, Tafel polarization and Electrochemical Impedance Spectroscopy (EIS), Fourier Transform Infra-red Spectroscopy (FTIR). The results of weight loss studies correlated well with those of polarization and Impedance Spectroscopy. Inhibition performance for both Caesalpinia Sappan L modified imidazoline ( CS IMI) and Imidazoline (IMI) increases with increasing inhibitor concentration. The formulated Caesalpinia Sappan L modified imidazoline ( CS IMI), and Imidazoline (IMI) inhibitors give a greater than 90% inhibition efficiency with dosage 25 ppm at a temperature of 90-140°F. Caesalpinia Sappan L modified imidazoline (CS IMI), and Imidazoline (IMI) show comparable inhibition performance. However, at temperature 140oF, Imidazoline (IMI) seems to have a slightly better performance, indicating better thermal stability. Caesalpinia sappan bioactive agents are brazilein and chalcone, and its inhibition mechanism by physisorption obey Langmuir Isotherm, this mode will control charge transfer at surface metal and electrolyte.This result confirms that Caesalpinia sappan modified imidazoline is very promising for the development of green corrosion inhibitors for oil and gas application