Influence of the Supernatant of Trehalose-Lipid Culture Liquid on the Corrosion of 20 Steel and Aluminum in Chloride Sol
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INFLUENCE OF THE SUPERNATANT OF TREHALOSE-LIPID CULTURE LIQUID ON THE CORROSION OF 20 STEEL AND ALUMINUM IN CHLORIDE SOLUTIONS Z. V. Slobodyan,1,2 L. А. Mahlatyuk,1 R. B. Kupovych,1 N. І. Koretska,3 and Ya. І. Zin’1
UDC 620.197.3
It is shown that the supernatant of trehalose-lipid culture liquid, which is the product of vital activity of R.erythropolis Au-1 bacteria, exerts an anticorrosion influence on 20 steel and aluminum both in a 0.1% NaCl medium and in a model solution of stratal water. Thus, in 0.1% NaCl, within the temperature range 25–50°С, the supernatant of trehalose-lipid culture liquid makes the corrosion rate of 20 steel 6.2–4.3 times lower and the corrosion rate of aluminum 2–3.8 times lower. At the same time, in the model solution, the corrosion rates become 2.9–1.5 times lower for 20 steel and 3.1–3.2 times lower for aluminum. It is shown that the inhibiting properties of the supernatant of trehalose-lipid culture liquid are explained by its retarding action upon both electrode reactions caused by its adsorption on the metal surfaces. Keywords: supernatant of trehalose-lipid culture liquid, corrosion rate, coefficient of corrosion inhibition, corrosion potential, corrosion current, Tafel constants.
Introduction In recent years, the attention of numerous researchers in the field of corrosion protection has been focused on the creation and investigation of new ecological methods aimed at increasing the residual service life of equipment and, in particular, at the development of the so-called “green” corrosion inhibitors. First of all, this is required for the corrosion protection of water circulation systems, the reduction of the level of aggressiveness of stratal waters in low-yield wells, etc. The urgency of this approach is mainly explained by the catastrophic deficiency of the available amounts not only of fresh but also of weakly mineralized waters [1]. Green corrosion inhibitors are developed in several directions, namely, the synergistic compositions are created on the basis of the extracts of plant raw materials [2–4], by using the products of vital activity of microbial organisms [5–7], and as a result of synthesis of organic analogs of natural materials [8]. The most cost-saving method is connected with the production of inhibitors from the wastes of processing of plant raw materials, especially in thickly wooded regions. However, the experience of operation of these substances reveals their higher efficiency in acid media and the necessity of seeking new ecologically pure synergists aimed at increasing their protective ability in neutral media [9, 10]. By the method of microbial synthesis of eco-friendly inhibitors, it is possible to produce highly efficient products but, in this case, it is necessary to take into account the decay of their anticorrosive properties as a result 1 2 3
Karpenko Physicomechanical Institute, National Academy of Sciences of Ukraine, Lviv, Ukraine. Corresponding author; e-mail: [email protected].
Department of Physicochemistry of Fossil Fuels, Lytvynenko I
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