The use of ellipsometry for studying the adsorption of organic corrosion inhibitors from aqueous solutions on metals. Review. Part 2. Adsorption of salts of organic acids and azoles

• N.P. Andreeva¹, Yu.I. Kuznetsov¹ 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, 394018 Voronezh, Russian Federation

Abstract: In the first part of this review, a technique for obtaining adsorption isotherms by the ellipsometric method was presented and a brief analysis of theoretical adsorption isotherms was given. Analyzing the literature in which the ellipsometric method was used, we noted that it was used mainly to determine the thicknesses of adsorbed layers. In the second part of the review, we will consider examples of studying the adsorption of well-known organic corrosion inhibitors (CIs) on the metal surface using this method. These include salts of carboxylic and phosphonic acids, organophosphates (salts of acid dialkyl phosphates), and azoles. An important advantage of using ellipsometry in aqueous or aqueous-organic solutions is the possibility of its combination with electrochemical measurements. It makes it possible to study adsorption in a wide range of potentials. Examples of adsorption of a mixture of CIs and induced adsorption are given, the possibility of enhancing the adsorption of BTA by small additions of dimegin to a solution on iron and copper is shown. Depocolin has been proposed as a surface modifier for copper and MNZh5-1 alloy. The conditions for preparing the surface of magnesium and aluminum to obtain adsorption isotherms are considered in detail. Adsorption isotherms of the following sodium salts of higher carboxylic acids were obtained on magnesium: sodium oleyl sarcosinate, sodium oleate, and sodium linoleate from a borate solution with pH 11.2. Determination of the thicknesses of the adsorbed layers suggests their location on the surface. The thicknesses of the adsorbed layers of depocolin and dimegin on nickel determined by the ellipsometric method and XPS coincide within the measurement error. For some inhibitors, kinetic adsorption isotherms have been obtained, which can be adequately described by the Roginsky–Zeldovich slow chemisorption equation.

Keywords: ellipsometry, adsorption isotherms, Temkin isotherm, XPS, dimegin, depocolin, BTA, sodium N-phenylanthranilate, oleyl sarcosinate, sodium oleate, kinetic adsorption isotherms

Int. J. Corros. Scale Inhib., 2023, 12, no. 2, 560-585
doi: 10.17675/2305-6894-2023-12-2-10

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