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Experimental and Theoretical Studies of Media Effects on Copper Corrosion in Acidic Environments Containing 2-Amino-5-mercapto-1,3,4-thiadiazole

M. Lashgari^a,*, M.R. Arshadi ^b and M. Biglar ^a

^aDepartment of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), P.O. Box 45195-1159,Zanjan, Iran
^bDepartment of Chemistry, Sharif University of Technology, P.O. Box 11365-9516, Tehran, Iran

Corrosion behaviour of copper metal in acid solutions (HCl, H₂SO₄ and H₃PO₄) containing 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) was investigated experimentally and theoretically via gravimetric, potentio-dynamic and quantum electrochemical approaches. Similar behavior was observed for H₂SO₄ and H₃PO₄ media, and related to the nature of anions at metal/solution interface. With regard to HCl, however, the rate of corrosion was determined to be low at initial stages, but high later on using an auto-catalyzing mechanism. In the presence of AMT, the experimental studies revealed that this molecule was a good anodic-type inhibitor causing substantial changes in corrosion potential. Moreover, its adsorption obeys the Langmuir isotherm. The values of ΔG_ads were determined and correlated to the inhibitor powers. Finally, the influence of media (anions) on metal corrosion was also investigated from molecular point of view by calculations of the copper-anions interaction using density functional theory.

Keywords: Copper corrosion inhibitors, Media effect, Autocatalysis, Specific adsorption, Molecular electrochemistry