Effective inhibition on the corrosion of X65 carbon steel in the oilfield produced water by two Schiff bases

The failure of carbon steel pipelines due to corrosion is a serious problem in the oil and gas exploitation. In this study, two new Schiff bases, 5-((3-phenylallylidene)amino)-1,3,4-thiadiazole-2-thiol (PATT) and 5-((thiophen-2-ylmethylene)amino)-1,3,4-thiadiazole-2-thiol (TATT), were synthesized as inhibitors to inhibit the corrosion of X65 carbon steel in the CO2-saturated oilfield produced water. Electrochemical measurements and surface analysis show that both PATT and TATT exhibit significant inhibition effect by predominant inhibition of anodic process. The considerable negative standard Gibbs free energy indicates that the adsorptions of PATT and TATT are primarily chemisorption. Molecular dynamics simulations show that both PATT and TATT adsorb on Fe surface in flat orientation. PATT exhibits a higher inhibition effect than TATT, which has been demonstrated by experimental measurements and theoretical calculations.