Exploring the Hydrophobic Effects of Quaternary Ammonium Copolymers on Corrosion of Casing and Tubing Steel in Acidic Solution

Abstract The hydrophobic characteristic of corrosion inhibitors increases inhibition efficiency and lowers corrosion rates by promoting better adsorption onto metal surfaces and forming a more effective barrier against corrosive substances. In this study, three AMCs with varying hydrophobic properties were tested to examine their capacity to suppress P110 CS corrosion in 15% HCl is studied. The electrochemical studies demonstrated that AMCs with hydrophilic and hydrophobic ratios of 100, 90:10, and 80:20 showed the %IE of 87.74%, 92.12%, and 93.53%, respectively. The OCP and PDP studies demonstrate that AMCs effectively replace the pre-adsorbed water molecules at the active areas of the metallic surface as mixed-type corrosion inhibitors because they prevent both anodic and cathodic reactions without appreciably changing the corrosion potential. They work by forming a corrosion-inhibiting coating on the metal surface through adsorption, based on the Langmuir isotherm concept. The results of the DFT analysis indicate that the adsorption and charge-sharing processes involve significant involvement from quaternary nitrogen atoms of hydrophilic and hydrophobic moieties. Finally, a schematic representation based on the concept from electrochemical, surface, and computational research is used to explain the corrosion inhibition mechanism of AMCs.