Competitive adsorption of Cu²⁺ and chloride ions, polyethylene glycol and sulfur-containing organic additives on copper in sulfuric acid electrolytes

• N.P. Andreeva¹, I.A. Kuznetsov¹, A.A. Chirkunov¹, V.A. Polikarchuk², M.S. Derkachev², O.A. Kozaderov², N.V. Sotskaya² and Kh.S. Shikhaliev²

¹ A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation
² Voronezh State University, Universitetskaya pl. 1, Voronezh, 394018, Russian Federation

Abstract: A model electrolyte (0.5 M H₂SO₄ + 0.1 g/L CuSO₄) was proposed to study the co-adsorption of chloride ions and organic additives by the ellipsometric method. Commercial additives Avangard, APhDS (bis(2-aminophenyl)disulfide), and the PEG-115 inhibitor employed in copper electrodeposition were used as brightening agents. The mixture of NaCl and PEG-115 is practically not adsorbed on the electrode. Avangard and APhDS enhance the adsorption of NaCl and PEG-115 when added sequentially. Comparison of the effect of Avangard and APhDS on the adsorption of the mixture (NaCl + PEG-115) shows that APhDS additive has a stronger stimulating effect on adsorption. The adsorption isotherm of APhDS on the surface of a copper electrode from the 0.5 M H₂SO₄ + 0.1 g/L CuSO₄ solution at E=0 V was obtained. The adsorption isotherm is described by the Temkin equation. The value of adsorption free energy –ΔG⁰_ads =33.57 kJ/mol suggests chemical adsorption of APhDS on the surface.

Keywords: copper, adsorption, ellipsometry, Temkin isotherm, brightening agent

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 2482-2495
doi: 10.17675/2305-6894-2023-12-4-54

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