Thiadiazoles as corrosion inhibitors for carbon steel in H2SO4 solutions

Abstract

Six organic compounds derived from 2-amino-5-alkylthiadiazole were evaluated as corrosion inhibitors of carbon steel 1018 (CS 1018) in 1.0 M H2SO4. The inhibition efficiency displayed by the synthesized compounds was assessed by mass loss, using a concentration interval of 10-100 ppm at 25 and 40 °C. The potentiodynamic tests were carried out only with the compounds that showed the lowest [AMT], intermediate [AHT] and highest [ATT] inhibition efficiencies obtained by mass loss. The inhibition efficiency results obtained by both techniques showed that the length of the alkylic chain in this kind of compounds plays a major role in their optimum performance as corrosion inhibitors. In addition, from the analysis of the calculated electrochemical parameters, it was found that the evaluated compounds present properties of mixed-type inhibitors.As for the adsorption mechanism on the CS 1018 metal surface in 1.0 M H2SO4, it was found to be of physical type. The characterization of the corrosion products formed on CS has been carried out by 57Fe Mo{double acute}ssbauer spectroscopy. The major constituent of the rust formed in this environment in the presence of 2-amino-5-alkylthiadiazole is Szomolnokite. © 2013 by ESG.