Inhibitive effect of 1,3,4-thiadiazole-2,5-dithiol on copper corrosion in chloride media

• S. Echihi^1,2, M. Tabyaoui² and W. Qafsaoui¹

¹ Laboratory of Water and Environment, Faculty of Sciences, BP 20, 24000, El Jadida, Morocco
² Laboratory of Nanotechnology, Materials and Environment, Faculty of Sciences, Av. Ibn Battouta, BP 1014 RP, M-10000, Rabat, Morocco

Abstract: Corrosion inhibition of copper by 1,3,4-thiadiazole-2,5-dithiol (DMTD) was investigated in 0.1 M NaCl solution using electrochemical methods, surface and solution analysis. Polarization tests results showed that DMTD inhibits efficiently copper corrosion, prevents oxide formation and revealed a marked effect of mixed inhibition after 1 h and 24 h immersion. Electrochemical impedance spectroscopy (EIS) measurements corroborate these results and indicate that the value of polarization resistance increased with DTMD concentration for 1 h immersion time. Addition of 10^–2 M DMTD in the test solution exhibited a maximum inhibitive efficiency of 97% up to 24 h immersion. Surface analysis techniques were conducted on copper specimens after 24 h immersion in 0.1 M NaCl solution. SEM/EDX results confirmed that DMTD forms an adsorbed protective layer on copper surface which was found to be hydrophobic as indicated by contact angle (CA) measurements. These results were further confirmed by XRD patterns which indicated the lack of crystallized corrosion products. Cl^– and Cu²⁺ ions concentrations in the solution, after 30 days immersion of copper sheet in 0.1 M NaCl solution with and without 10^–2 M DMTD, were determined by ionic chromatography (IC) and conducted by Inductively Coupled Plasma–Atomic Emission Spectroscopy (ICP–AES) respectively. The results showed that without DMTD Cl^– concentration decreases, while Cu²⁺ one increases due to corrosion process. In contrast, in the presence of 10^–2 M DMTD chloride ions concentration remained practically unchanged (0.099 mol/L) and Cu²⁺ concentration is quite low.

Keywords: copper, EIS, SEM/EDX, XRD, ICP–AES, IC, neutral inhibition

Int. J. Corros. Scale Inhib., 2019, 8, no. 2, 329-355 PDF (1 681 K)
doi: 10.17675/2305-6894-2019-8-2-14

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