Inhibition of Steel Microbial Corrosion by Quaternary Salts of Imidazoquinolinium

The 2.3-diaryl-4.5-dihydro-imidazo[1.2-a]quinolinium-3 bromides were tested as biocides and inhibitors of microbial corrosion of low-carbon steel induced by bacteria of Desulfovibrio sp. M-4.1 strain. The degree of metal protection against corrosion induced by sulfate-reducing Desulfovibrio sp. M-4.1 bacteria was 84.6–92.4%. 2-(para-tolyl)-3-(41-methoxyphenyl)-4.5-dihydro-imidazo[1.2-a]quinolinium bromide demonstrated the best protective effect. It was established that sulphate-reducing bacteria of Desulfovibrio sp. M-4.1 strain were sensitive to 2.3-diaryl-4.5-dihydro-imidazo[1.2-a]quinolinium-3 bromides. Under the influence of imidazoquinolinium quaternary salts, the inhibition zones of bacterial growth have the diameters of 24.7–45.5 mm. Quaternary salts of imidazoquinolinium completely suppress the growth of sulfate-reducing Desulfovibrio sp. M-4.1 bacteria in plankton and significantly influence the formation of biofilm (the number of cells decreases by 6–8 orders compared to the control sample) under conditions of microbial corrosion. Suppression of the sulfate-reducing activity of Desulfovibrio sp. M-4.1 bacteria by quaternary salts of imidazoquinolinium (by 88.8–91.6%) was proven. The effectiveness of the quaternary salts was discussed with the account of molecular descriptors.