Application of Some Anionic Surfactants Based on Corn Oil as Corrosion Inhibitors for Carbon Steel in CO2 Environments

V. M. Abbasov *Hany M. Abd El-Lateef L. I. Aliyeva I. T. Ismayilov
Mamedaliev Institute of Petrochemical Processes National Academy of Sciences of Azerbaijan AZ1025 Baku Azerbaijan
*Chemistry Department Faculty of Science Sohag University 82524 Sohag Egypt
*E-mail: Hany_shubra@yahoo.co.uk

One of the major internal corrosion problems is carbon dioxide corrosion. Carbon dioxide gas dissolves in the produced water and results in the formation of carbonic acid which gives rise to acid corrosion of carbon steel pipelines. Organic corrosion inhibitors have been widely and successfully used to maintain or increase the use of carbon steel in oilfields. They inhibit corrosion by forming an adsorbed organic compound film on the steel surface [1].
Specific types of organic inhibitors are represented by surfactants. Nowadays surfactants are widely used and find a very large number of applications in the petroleum industry. This is attributed to their significant capability to influence the properties of surfaces and interfaces [2].
In this work we have synthesized environmental surfactants based on corn oil and studied their inhibition properties in CO2-saturated solutions at elevated temperatures. The structures of synthesized surfactants were confirmed by physical-chemical spectroscopic methods. The surface activity of the synthesized surfactants solutions was determined using surface and interfacial tension measurements at 25 °C.
It was found that the series of synthesized surfactants ([R-CH-(OSO3M)-COOM]; where M=Na+ K+ NH4+ -HN-CH2-CH2-OH -N-(CH2-CH2-OH)2) are most effective than ethanolamines salts of fatty acids. The results showed that all synthesized inhibitors were good inhibitors and their inhibition efficiencies were significantly increased with increasing the concentration of inhibitor. The increase of inhibition efficiency with increasing the concentration can be interpreted on the basis of the adsorption amount and the coverage of surfactants molecules increases with increasing concentration. The maximum inhibition efficiencies ranged between 98.55% and 99.90 % at 100 ppm. It was also the purpose of the present work to test the experimental data obtained with several adsorption isotherms at test temperature in order to determine the thermodynamic functions for the adsorption process and gain more information about the mode of adsorption. The Adsorption of surfactants was found to obey Langmuir isotherm and was chemisorption.
The morphology of the tested sample was observed by Energy dispersive X-ray fluorescence (EDRF) and scanning electron microscope (SEM). The results reveal that the most of electrode surface in the presence of studied inhibitors is covered by protective layer and surface became more smoothly. This suggests that the inhibitors are strongly adsorbed on carbon steel surface and this hinders the corrosion process.

Keywords: Anionic surfactants Corn oil Carbon steel CO2 environments

References
1. Hany M. Abd El-Lateef V. M. AbbasovL.I.Aliyeva N.S. Ahmedov Corrosion behavior of steel in carbon dioxide environment Processes of Petrochemistry and oil refining Volume 12 ? 4 (48) (2011) 231-247.
2. Maqsood Ahmad Malik Mohd Ali Hashim Firdosa Nabi Shaeel Ahmed AL-Thabaiti Zaheer Khan Anti-corrosion Ability of Surfactants: A Review Int. J. Electrochem. Sci. 6 (2011) 1927 – 1948.