Two kinds of thioureas, 1-N-(1′-(1′,2′,4′-triazole))acetyl-4-N-benzoylthiosemicarbazide (TBU) and 1-N-(1′-(1′,2′,4′-triazole))Methyl-4-N-(3″,5″-dimethyl)benzoylthiosemicarbazide (TDBU) were synthesized and characterized as corrosion inhibitors in 1 mol/L hydrochloric acid to mild steel by weight loss measurement, electrochemical measurement, quantum chemistry calculation and molecular dynamics simulation. The results demonstrate that TBU and TDBU are good inhibitors that could reduce anodic dissolution and retard the hydrogen evolution reaction with the order TBU > TDBU, and that the corrosion inhibition efficiency increases with the increasing thiourea concentration. TBU has a remarkably high inhibition efficiency of 97.5% at a concentration of 1.0 × 10−3 mol/L. The adsorptions of TBU and TDBU on mild steel accord with the Langmuir model. The results of quantum chemical study indicate that the S atom contributes to the adsorption of the corrosion thiourea molecules. The steric hindrance of the methyl group, not an electronic effect, was suggested as the main influencing factor on the inhibition efficiency of the two thioureas, which is relatively rare in literature reports.
Mild steel Corrosion inhibitor Electrochemical measurement Weight loss Theoretical study
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The work carried out was supported by the National Nature Science Foundation of China (51671117) and Shanghai City Committee of science and technology research program key support project (13231203000).
1.State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, College of Resources and Environmental EngineeringEast China University of Science and TechnologyShanghaiChina