The Role of Some Cationic Surfactants Based on Thiazine as Corrosion Inhibitors in Petroleum Applications: Experimental and Theoretical Approach

Mohamed A Moselhy; Elsayed Gamal Zaki; Samir Abd El Hady Abd El-Maksoud; Mohamed A Migahed

doi:10.1021/acsomega.2c02961

The Role of Some Cationic Surfactants Based on Thiazine as Corrosion Inhibitors in Petroleum Applications: Experimental and Theoretical Approach

ACS Omega. 2022 Aug 31;7(36):32014-32025. doi: 10.1021/acsomega.2c02961. eCollection 2022 Sep 13.

Authors

Mohamed A Moselhy¹, Elsayed Gamal Zaki², Samir Abd El Hady Abd El-Maksoud³, Mohamed A Migahed²

Affiliations

¹ Belayim Petroleum Company, Cairo 7074, Egypt.
² Egyptian Petroleum Research Institute, Nasr City, Cairo 11727, Egypt.
³ Chemistry Department, Faculty of Science, Port Said University, Port Said 42522, Egypt.

Abstract

Two cationic surfactants based on thiazine, dodecyl thiazin bromide (DTB) and hexyl thiazin bromide (HTB), were synthesized, characterized, and investigated as corrosion inhibitors for API X-65 type steel in oil wells' formation water under an H₂S environment. Various spectroscopic techniques such as FTIR and ¹H NMR were used to confirm the DTB and HTB chemical structures. The corrosion inhibition efficiency of the selected compounds was investigated using both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The innovation of the current study is the existence of a long chain in the inhibitor molecule, which leads to an increase in the performance of the surfactant as a corrosion inhibitor, due to the increase in the surface area per molecule. It was found that these surfactants act as mixed-type inhibitors, leading to suppression of both the cathodic and the anodic processes by its adsorption on the electrode surface according to the Langmuir adsorption isotherm. Carbon steel's inhibitory mechanism was studied using an analogous circuit. The scanning electron microscope technique was used as a suitable analysis tool to show the nature of the layer designed on carbon steel. Quantum chemical calculations and Monte Carlo simulation techniques were used to support the obtained experimental results. Finally, a suitable mechanism for the inhibition process was proposed and discussed.