S.M.A Hosseini - Departm ent of Chemistry,Faculty of Science,Shahid Bahonar University of Kerman
A Azimi - Departm ent of Chemistry,Faculty of Science,Shahid Bahonar University of Kerman
M.J Bahrami - Departm ent of Chemistry,Faculty of Science,Shahid Bahonar University of Kerman

Carbon steels are the most commonly used construc tion materials for pipe lines in the oil and gas industry. The y are, however, very susceptible to corrosion in envir onment containing CO۲ [۱]. Carbon dioxide corrosion of carbon steel p ipelines and equipme nt in the oil and gas industr y has been given muc h attention in recent years becaus e of an inc reased ten dency to inject C O۲ into oil wells to reduce the viscosity of oil and increase its production [۲, ۳]. An importa nt fact is t hat when CO۲ dissolve s in water, carbonic acid (H۲CO۳) is produ ced with the characteristic that is more aggressi ve than hy drochloric acid at the same pH [۴]. The problem s arising from CO۲ corrosion have led to the development of various m ethod of corrosi on control which includes the inj ection of co rrosion inhibitors that has proven to be a practica l and econ omical method to co ntrol CO۲ corrosion [۵]. These organic co mpounds inhibit the corros ion of mil d steel by adsorption on the me tal-solutio n interface thereby creatin g a barrier that prevent s the activ e ions in the corrosion reactions to get to the surface [۶]. Thi ourea (TU ) and its derivatives ha ve been st udied for more than four decades because they in hibit the corrosion of steels and are superior to amine-based inhibitors in acidic media [۷–۹]. However, th iourea is se ldom used in a neutral medium because of its inefficiency [۱۰]. In this research the adsorption and inhibition effect of two corr osion inhibi tor (OI and TU) on carbon steel surface in CO۲-saturated ۳% NaCl solution were studied and then, co-adsorption effect of them inve stigated.

Corro sion inhibit or; Synergi stic effect; adsorption; CO۲ corro sion