Synergistic Inhibition Effect of Imidazoline Ammonium Salt and Sodium Dodecyl Sulfate in CO<sub>2</sub> System

Abstract

The synergistic inhibition effect of the imidazoline ammonium salt(IAS) and sodium dodecyl sulfate(SDSH) on the corrosion of Q235 carbon steel in a CO2 saturated brine solution was studied by weight loss,electrochemical impedance spectroscopy(EIS),Tafel polarization measurements,X-ray photoelectron spectrometry(XPS),and scanning electron microscopy(SEM).We found that in the CO2 saturated brine solution,a good synergistic inhibition effect exists between IAS and low concentrations of SDSH,and the most significant synergistic inhibition occurred at a concentration ratio of 1:1(50 mg·L-1: 50 mg·L-1) with an inhibition efficiency of 88.5%.However,antagonism occurs upon mixing IAS with a high concentration of SDSH.In this paper,the mechanisms of the synergistic and antagonistic effects are analyzed using a reasonable adsorption model.Good corrosion inhibition on Q235 carbon steel was also found when only using a high concentration of SDSH with an inhibition efficiency of about 90%.Both the adsorption processes of SDSH and IAS on the surface of Q235 carbon steel are spontaneous processes and the former process complies with the Frumkin adsorption model while the later complies with the Temkin adsorption model.