Inhibition performance of benzimidazole derivatives with different heteroatoms on the under-deposit corrosion of carbon steel in CO2-saturated solution

Abstract

Inhibition performance of 2-hydroxybenzimidazole (2-OH-BI), 2-aminobenzimidazole (2-NH2-BI) and 2-mercaptobenzimidazole (2-SH-BI) on under-deposit corrosion (UDC) of carbon steel beneath CaCO3 and SiO2 deposits in CO2-saturated solutions were investigated by electrochemical measurements and surface analyses. The results show that the inhibition efficiency follows the order of 2-SH-BI > 2-NH2-BI > 2-OH-BI. All inhibitors are efficient for inhibiting UDC under CaCO3 deposit while only 2-SH-BI exhibits > 90% efficiency under SiO2 deposit. The UDC inhibition mechanisms are explained in terms of the intrinsic corrosion inhibition performance, adsorption on deposits and penetration through deposits of inhibitors, which verifies the design strategy for an ideal UDC inhibitor.