Adsorption and passivation of copper by 2-aminobenzothiazole in neutral chloride solutions

• M.O. Agafonkina, N.P. Andreeva and Yu.I. Kuznetsov

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia

Abstract: 2-Aminobenzothiazole (2-ABT) was studied as a probable copper corrosion inhibitor in aqueous solutions using a combination of adsorption, polarization, and gravimetric studies. Polarization studies showed that in a borate buffer solution + 0.01 mol/L NaCl, the addition of 2-ABT with C_in=0.1 mmol/L is capable of passivating copper. Not surprisingly, 2-ABT begins to adsorb on the oxidized copper surface at very low concentrations (at C_in=0.0063 mmol/L) with an adsorption free energy of 70.2 kJ/mol. This indicates a chemisorption interaction between 2-ABT and the copper surface. The adsorption of 2-ABT on copper increases if polyethyleneglycol (PEG-115) is pre-adsorbed on it. The adsorption of PEG-115 on the electrode modified with 2-ABT also increases, meaning that 2-ABT and PEG-115 mutually enhance each other. The thicknesses of the conditional monolayers of the studied compounds on oxidized copper were also calculated from the adsorption measurement results. Another factor enhancing the protective effect of 2-ABT and its composition with PEG-115 on copper is the exposure time in the inhibited solution. Corrosion tests of copper in an aqueous solution of 0.001 mol/L NaCl showed that 100% copper protection is achieved at 0.9 mmol/L 2-ABT. The introduction of 5.0 mg/L PEG-115 reduces the 2-ABT concentration required for complete copper protection from 0.9 to 0.75 mmol/L.

Keywords: copper, passivity, degree of protection, Temkin adsorption isotherm, 2-amino-benzothiazole, thiazoles, polyethyleneglycol PEG-115, co-adsorption, ellipsometry

Int. J. Corros. Scale Inhib., 2026, 15, no. 2, 476-493
doi: 10.17675/2305-6894-2026-15-2-25

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