Study of volatile corrosion inhibitors by infrared spectroscopy

Abstract

In practice, it often becomes necessary in practice to identify a particular substance or chemical product as a whole, and also to quantify their content in the developed material. Corrosion inhibitors are special chemicals that retard the process of chemical and physical reactions. Determination of the minimum permissible concentration of the inhibitor in anticorrosive papers has an important practical significance because it specifies the duration of their protective effect. The possibility of practical application of infrared (IR) spectroscopy is considered in the study of structural features of volatile corrosion inhibitors and packaging materials with these inhibitors. Koring 501, Koring 505 inhibitors of Cortec Corporation (USA) and UNI inhibitor (a mixture of sodium nitrite and urotropine in a ratio of 1:1, Russia) were used as volatile corrosion inhibitors for anticorrosive packaging materials preparation. Aqueous solutions of inhibitors containing 5 % (wt.) of the active substance were applied on the surface of creped paper with thermoplastic polymer lamination on one side by roller method. IR spectra of pure inhibitors and inhibited samples of packaging material were plotted on an IR Fourier spectrometer FT 801. The IR spectra of each inhibitor exhibit peaks that are unique to it. This will allow the inhibitors to be distinguished from each other. It was found by means of IR analysis that the composition of foreign inhibitors includes compounds containing nitrite ions (NO2‒). It is shown that the IR spectroscopy can be used to control the quality of the anticorrosive packaging materials. This is particularly topical in the conditions of import substitution.