The inhibition efficiency of сarvacrol as a non toxic volatile corrosion inhibitor for the temporary protection of mild steel was investigated. Weight loss measurements were used to measure the corrosion rate in the absence and presence of these volatile inhibitor compounds. It is demonstrated that the corrosion rate of steel decreases as its concentration increases, and the process of formation of films from the vapor phase has a long-term character. Atomic force microscopy (SEM) revealed that a protective film was formed on the surface of the inhibited sample. Fourier transform infrared (FT-IR) spectroscopy was used to characterize the adsorption of carvacrol on the steel surface. The results suggest the formation of an adsorbed inhibitor film on the steel surface, leading to a decrease in corrosion rate. Persistency experiments were also performed to evaluate the residence time for inhibitors adsorbed on carbon steel. Among the inhibitors tested, inhibitor showed very good corrosion inhibition properties as well as high persistency. The results show that carvacrol, as a mixed inhibitor, had good volatility and short induction period. The adsorption capacity of carvacrol was evaluated using quantum chemical calculations.

The microbiological composition of the biofilm, formed on the surface of sewage treatment constructions grids, and the seasonal variation in the number of its main components were examined. The strain Ch.5 was isolated and identified from the enrichment culture of sulfate-reducing bacteria. It was classified as belonging to Desulfomicrobium genus according to its physiological and biochemical characteristics.

Abstract.1 A number of new quaternary pyridinium salts with amide fragment and aryl substituents have been obtained, demonstrating the inhibition efficiency of 50.0-97.2 % under the biocorrosion of mild steel, induced with sulfate-reducing bacteria of Desulfovibrio and Desulfomicrobium genera. It has been established that inhibition efficiency of the studied quaternary salts is caused by their effect on microbiological factor.

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Abstract.1 Aminooxoethylpyridinium chlorides under the St3ps steel corrosion in acid hydrochloric and sulfuric solutions demonstrate the inhibition efficiency at 98 %. The compound with hydrazinocarbonyl and 2,3-dimethylphenyl fragments turns out to be the most effective within the interval 293-333 К. This inhibitor is also characterized by a significant aftereffect due to the chemisorption on the steel surface.