Archive / Volume LX 2020

Olha HULAI¹, Vasylyna SHEMET¹, Vasyl ZHILKO², Olena KLYMOVYCH²

¹Lutsk National Technical University, Lvivska st., 75, 43018 Lutsk, Ukraine, hulay@i.ua

²Volyn Scientific Research Forensic Center of the MIA of Ukraine, Vynnychenka st., 43, 43000 Lutsk, Ukraine

DOI: https://doi.org/10.37827/ntsh.chem.2020.60.107

INHIBITOR EFFICACY AND COMPOSITION OF OAK BAR EXTRACT.

Abstract. Regional and international researchers have proven that natural products, plants and their extracts can be used to reduce the corrosion rate. Such studies are relevant because natural inhibitors are obtained from renewable sources, therefore they are environmentally friendly. Ukrainian scientists have investigated the inhibition effect of oak bark extracts, but no such studies have been performed on cast iron. What is more, it has not been established which substances cause this effect. The purpose of the study is to determine the corrosion resistance of 08kp steel and gray cast iron SCh-15 (common structural materials of food industry equipment) in acidic and neutral environments in presence of oak bark extracts; to define the qualitative composition of the extract.
Structure of cast iron and steel samples was studied on a metallographic microscope MMP-14C. The corrosion rate of metals was evaluated by weight. To determine the corrosion potential, we used a setting of a cathode voltmeter, electrodes (test and saturated chloride-silver), an intermediate vessel with a saturated KCl solution and electrolytic keys filled with the test electrolyte and saturated KCl solution (for the comparison electrode). The extract was analyzed on a Shimadzu GCMS-QP2020 gas chromatograph with mass-selective detection.
Using weight method, the inhibition effect of oak shavings alcohol extract was proved in acidic and neutral corrosive environments. Under the influence of oak bark extract (5%), the stationary potential of steel 08kp has shifted: in 3% NaCl solution (oxygen depolarization) – towards more negative values; in 5% HCl solution (hydrogen depolarization) – to less negative values. Gas chromatography with mass-selective detection (GC/MS) revealed that the active substance in the extract is a mixture of natural tannins – polyphenolic compounds with a molecular weight of 500 to 3000. The inhibition effect of natural tannins is probably enhanced by siloxane compounds.

Keywords: corrosion rate, «green» inhibitors, oak bark extract.

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How to Cite

Hulai O., Shemet V., Zhilko V., Klymovych O. INHIBITOR EFFICACY AND COMPOSITION OF OAK BAR EXTRACT Proc. Shevchenko Sci. Soc. Chem. Sci. 2020 Vol. LX. P. 107-117.

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